Patent Application
20110256531
Various tests are available that can be used to assess the presence of biological analytes in a sample (e.g. surface, water, air, etc). Such tests include those based on the detection of ATP using the firefly luciferase reaction, tests based on the detection of protein using colorimetry, tests based on the detection of microorganisms using microbiological culture techniques, and tests based on detection of microorganisms using immunochemical techniques. Surfaces can be sampled using either a swab device or by direct contact with a culture device such as an agar plate. The sample can be analyzed for the presence of live cells and, in particular, live microorganisms.
Results from these tests are often used to make decisions about the cleanliness of a surface. For example, the test may be used to decide whether food-processing equipment has been cleaned well enough to use for production. Although the above tests are useful in the detection of a contaminated surface, they can require numerous steps to perform the test, they may not be able to distinguish quickly and/or easily the presence of live cells from dead cells and, in some cases, they can require long periods of time (e.g., hours or days) before the results can be determined.
The tests may be used to indicate the presence of live microorganisms. For such tests, a cell extractant is often used to release a biological analyte (e.g., ATP) associated with living cells. The presence of extracellular material (e.g., non-cellular ATP released into the environment from dead or stressed animal cells, plant cells, and/or microorganisms) can create a high “background” level of ATP that can complicate the detection of live cells.
In spite of the availability of a number of methods and devices to detect live cells, there remains a need for a simple, reliable test for detecting live cells and, in particular, live microbial cells.
In general, the present disclosure relates to articles and methods for detecting live cells in a sample. The articles and methods make possible the rapid detection (e.g., through fluorescence, chemiluminescence, or a color reaction) of the presence of cells such as bacteria on a surface. In some embodiments, the inventive articles are “sample-ready”, i.e., the articles contain all of the necessary features to detect living cells in a sample. In some aspects, the inventive articles and methods provide a means to distinguish a biological analyte, such as ATP or an enzyme, that is associated with eukaryotic cells (e.g., plant or animal cells) from a similar or identical biological analyte associated with prokaryotic cells (e.g., bacterial cells). Furthermore, the inventive articles and methods provide a means to distinguish a biological analyte that is free in the environment (i.e., an acellular biological analyte) from a similar or identical biological analyte associated with a living cell. Methods of the present disclosure allow an operator instantaneously to form a liquid mixture containing a sample and a hydrogel comprising a cell extractant. In some embodiments, the methods provide for the operator to, within a predetermined period of time after the liquid mixture is formed, measure the amount of a biological analyte in the mixture to determine the amount of acellular biological analyte in the sample. In some embodiments, the methods provide for the operator to, after a predetermined period of time during which an effective amount of cell extractant is released from the hydrogel into the liquid mixture, measure the amount of a biological analyte to determine the amount of biological analyte from acellular material and live cells in the sample. In some embodiments, the methods provide for the operator, within a first predetermined period of time, to perform a first measurement of the amount of a biological analyte and, within a second predetermined period of time during which an effective amount of cell extractant is released from the hydrogel, perform a second measurement of the amount of biological analyte to detect the presence of live cells in the sample. In some embodiments, the methods can allow the operator to distinguish whether biological analyte in the sample was released from live plant or animal cells or whether it was released from live microbial cells (e.g., bacteria). The present invention is capable of use by operators under the relatively harsh field environment of institutional food preparation services, health care environments and the like.
In one aspect, the present disclosure provides an article for detecting cells in a sample. The article can comprise an enclosure containing a hydrogel wherein the hydrogel comprises a cell extractant.
Articles of the present disclosure can comprise a sample acquisition device wherein the sample acquisition device comprises the enclosure.
Articles of the present disclosure can comprise a housing wherein the housing comprises the enclosure.
In another aspect, the present disclosure provides a sample acquisition device with a hydrogel comprising a cell extractant disposed thereon.
A hydrogel comprising a cell extractant can be coated on a solid substrate.
In another aspect, the present disclosure provides a kit. The kit can comprise a housing that includes an opening configured to receive a sample acquisition device and a hydrogel comprising a cell extractant. Optionally, the kit can further comprise a sample acquisition device.
“Biological analytes”, as used herein, refers to molecules, or derivatives thereof, that occur in or are formed by an organism. For example, a biological analyte can include, but is not limited to, at least one of an amino acid, a nucleic acid, a polypeptide, a protein, a polynucleotide, a lipid, a phospholipid, a saccharide, a polysaccharide, and combinations thereof. Specific examples of biological analytes can include, but are not limited to, a metabolite (e.g., staphylococcal enterotoxin), an allergen (e.g., peanut allergen(s), a hormone, a toxin (e.g., Bacillus diarrheal toxin, aflatoxin, etc.), RNA (e.g., mRNA, total RNA, tRNA, etc.), DNA (e.g., plasmid DNA, plant DNA, etc.), a tagged protein, an antibody, an antigen, and combinations thereof.
“Sample acquisition device” is used herein in the broadest sense and refers to an implement used to collect a liquid, semisolid, or solid sample material. Nonlimiting examples of sample acquisition devices include swabs, wipes, sponges, scoops, spatulas, pipettes, pipette tips, and siphon hoses.
As used herein, the term “hydrogel” refers to a polymeric material that is hydrophilic and that is either swollen or capable of being swollen with a polar solvent. The polymeric material typically swells but does not dissolve when contacted with the polar solvent. That is, the hydrogel is insoluble in the polar solvent. The swollen hydrogel can be dried to remove at least some of the polar solvent.
“Cell extractant”, as used herein, refers to any compound or combination of compounds that alters cell membrane or cell wall permeability or disrupts the integrity of (i.e., lyses or causes the formation of pores in) the membrane and/or cell wall of a cell (e.g., a somatic cell or a microbial cell) to effect extraction or release of a biological analyte normally found in living cells.
“Detection system”, as used herein, refers to the components used to detect a biological analyte and includes enzymes, enzyme substrates, binding partners (e.g. antibodies or receptors), labels, dyes, and instruments for detecting light absorbance or reflectance, fluorescence, and/or luminescence (e.g. bioluminescence or chemiluminescence).
The words “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.
The terms “comprises” and variations thereof do not have a limiting meaning where these terms appear in the description and claims.
As used herein, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably. Thus, for example, a housing that comprises “a” detection reagent can be interpreted to mean that the housing can include “one or more” detection reagents.
The term “and/or” means one or all of the listed elements or a combination of any two or more of the listed elements.
Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).
The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list.
The invention will be further explained with reference to the drawing figures listed below, where like structure is referenced by like numerals throughout the several views.
All patents, patent applications, government publications, government regulations, and literature references cited in this specification are hereby incorporated herein by reference in their entirety. In case of conflict, the present description, including definitions, will control.
Biological analytes can be used to detect the presence of biological material, such as live cells in a sample. Biological analytes can be detected by various reactions (e.g., binding reactions, catalytic reactions, and the like) in which they can participate.
Chemiluminescent reactions can be used in various forms to detect cells, such as bacterial cells, in fluids and in processed materials. In some embodiments of the present disclosure, a chemiluminescent reaction based on the reaction of adenosine triphosphate (ATP) with luciferin in the presence of the enzyme luciferase to produce light provides the chemical basis for the generation of a signal to detect a biological analyte, ATP. Since ATP is present in all living cells, including all microbial cells, this method can provide a rapid assay to obtain a quantitative or semiquantitative estimate of the number of living cells in a sample. Early discourses on the nature of the underlying reaction, the history of its discovery, and its general area of applicability, are provided by E. N. Harvey (1957), A History of Luminescence: From the Earliest Times Until 1900, Amer. Phil. Soc., Philadelphia, Pa.; and W. D. McElroy and B. L. Strehler (1949), Arch. Biochem. Biophys. 22:420-433.
ATP detection is a reliable means to detect bacteria and other microbial species because all such species contain some ATP. Chemical bond energy from ATP is utilized in the bioluminescent reaction that occurs in the tails of the firefly Photinus pyralis. The biochemical components of this reaction can be isolated free of ATP and subsequently used to detect ATP in other sources. The mechanism of this firefly bioluminescence reaction has been well characterized (DeLuca, M., et al., 1979 Anal. Biochem. 95:194-198).
The inventive articles and methods of the present disclosure provide simple means for conveniently controlling the release of biological analytes from living cells in order to determine the presence, optionally the type (e.g., microbial or nonmicrobial), and optionally the quantity of living cells in an unknown sample. The articles and methods include a hydrogel comprising a cell extractant. Methods of the present invention are disclosed in U.S. Patent Application Ser. No. 61/101,563, filed on Sep. 30, 2008 and entitled “BIODETECTION METHODS”, which is incorporated herein by reference in its entirety.
Articles of the present disclosure include a hydrogel. Suitable hydrogels include crosslinked hydrogels, swollen hydrogels, and dried or partially-dried hydrogels.
Suitable hydrogels of the present disclosure include, for example, the hydrogels, and polymeric beads made there from, described in International Patent Publication No. WO 2007/146722, which is incorporated herein by reference in its entirety.
Other suitable hydrogels include polymers comprising ethylenically unsaturated carboxyl-containing monomers and comonomers selected from carboxylic acids, vinyl sulfonic acid, cellulosic monomer, polyvinyl alcohol, as described in U.S. Patent Application Publication No. US2004/0157971; polymers comprising starch, cellulose, polyvinyl alcohol, polyethylene oxide, polypropylene glycol, and copolymers thereof, as described in U.S. Patent Application Publication No. US 2006/0062854; polymers comprising multifunctional poly(alkylene oxide) free-radically polymerizable macromonomer with molecular weights less than 2000 daltons, as described in U.S. Pat. No. 7,005,143; polymers comprising silane-functionalized polyethylene oxide that cross-link upon exposure to a liquid medium, as described in U.S. Pat. No. 6,967,261; polymers comprising polyurethane prepolymer with at least one alcohol selected from polyethylene glycol, polypropylene glycol, and propylene glycol, as described in U.S. Pat. No. 6,861,067; and polymers comprising a hydrophilic polymer selected from polysaccharide, polyvinylpyrolidone, polyvinyl alcohol, polyvinyl ether, polyurethane, polyacrylate, polyacrylamide, collagen and gelatin, as described in U.S. Pat. No. 6,669,981, the disclosures of which are all herein incorporated by reference in their entirety. Other suitable hydrogels include agar, agarose, polyacrylamide hydrogels, and derivatives thereof.
The present disclosure provides for articles and methods that include a shaped hydrogel. Shaped hydrogels include hydrogels shaped into, for example, beads, sheets, ribbons, and fibers. Additional examples of shaped hydrogels and exemplary processes by which shaped hydrogels can be produced are disclosed in U.S. Patent Application Publication No. 2008/0207794 A1, entitled POLYMERIC FIBERS AND METHODS OF MAKING and U.S. Patent Application Ser. No. 61/013,085, entitled METHODS OF MAKING SHAPED POLYMERIC MATERIALS, both of which are incorporated herein by reference in their entirety.
Hydrogels of the present disclosure can comprise a cell extractant. Hydrogels comprising a cell extractant can be made by two fundamental processes. In a first process, the cell extractant is incorporated into the hydrogel during the synthesis of the hydrogel polymer. Examples of the first process can be found in International Patent Publication No. WO 2007/146722 and in Preparative Example 1 described herein. In a second process the cell extractant is incorporated into the hydrogel after the synthesis of the hydrogel polymer. For example, the hydrogel is placed in a solution of cell extractant and the cell extractant is allowed to absorb into and/or adsorb to the hydrogel. An example of the second process is described in Preparative Example 5 below. A further example of the second process is the incorporation of an ionic monomer into the hydrogel, such as the incorporation of a cationic monomer into the hydrogel, as described herein in Preparative Example 2.
Hydrogels of the present disclosure may comprise a detection reagent system, such as an enzyme or an enzyme substrate. Such hydrogels can be used conveniently to store and/or deliver the detection reagent to a liquid mixture, comprising a sample and a cell extractant, for the detection of live cells in the sample.
An enzyme can be incorporated into a hydrogel during the synthesis of the hydrogel polymer. For example, luciferase can be incorporated into a hydrogel during the synthesis of the polymer, as described in Preparative Example 4 below. An enzyme can be incorporated into a hydrogel after the synthesis of the hydrogel. For example, luciferase can be incorporated into a hydrogel as described in Preparative Example 8 below.
An enzyme substrate can be incorporated into a hydrogel during the synthesis of the hydrogel polymer. For example, luciferin can be incorporated into a hydrogel during the synthesis of the polymer, as described in Preparative Example 3 below. An enzyme substrate can be incorporated into a hydrogel after the synthesis of the hydrogel. For example, luciferin can be incorporated into a hydrogel as described in Preparative Example 7 below.
A protein, such as an enzyme, can be incorporated into a hydrogel. For example, the incorporation of an enzyme (luciferase) into a hydrogel during the synthesis of the hydrogel is described in Preparative Example 4 below. Although proteins may be incorporated into the hydrogel during the synthesis of the hydrogel polymer, chemicals and or processes (e.g., u.v. curing processes) used in the polymerization process can potentially cause the loss of some biological activity by certain proteins (e.g. certain enzymes or binding proteins such as antibodies). Proteins can also be incorporated into a hydrogel after the hydrogel has been synthesized, as described in Preparative Example 8 below. Incorporation of the protein into the hydrogel after synthesis of the hydrogel can lead to improved retention of the protein's biological activity.
In some applications, it may be desirable that the hydrogel containing a cell extractant or detection reagent is in a dry or partially-dried state. Swollen hydrogels can be dried, for example, by methods known to those skilled in the art, including evaporative processes, drying in convection ovens, microwave ovens, and vacuum ovens as well as freeze-drying. When the dried hydrogel is exposed to a liquid or aqueous solution, the cell extractant or detection reagent can diffuse from the hydrogel. The cell extractant or detection reagent can remain essentially dormant in the bead until exposed to a liquid or aqueous solution. That is, the cell extractant can be stored within the dry hydrogel until the bead is exposed to a liquid. This can prevent the waste or loss of the cell extractant or detection reagent when not needed and can improve the stability of many moisture sensitive cell extractants or detection reagents that may degrade by hydrolysis, oxidation, or other mechanisms.
Hydrogels of the present disclosure can comprise a cell extractant. Chemical cell extractants include biochemicals, such as proteins (e.g., cytolytic peptides and enzymes). In some embodiments, the cell extractant increases the permeability of the cell, causing the release of biological analytes from the interior of the cell. In some embodiments, the cell extractant can cause or facilitate the lysis (e.g., rupture or partial rupture) of a cell.
Cell extractants include a variety of chemicals and mixtures of chemicals that are known in the art and include, for example, surfactants and quaternary amines, biguanides, surfactants, phenolics, cytolytic peptides, and enzymes. Typically, the cell extractant is not avidly bound (either covalently or noncovalently) to the hydrogel and can diffuse out of the hydrogel when the hydrogel is contacted with an aqueous liquid. In some embodiments, the precursor composition from which the hydrogel is made can contain an anionic or cationic monomer, such as described in WO 2007/146722 incorporated herein by reference, which is incorporated into the hydrogel and, as such can retain cell extractant activity. In some embodiments, the anionic or cationic monomers can be crosslinked to the surface of a hydrogel. Hydrogel beads or fibers can be dipped into a solution of the cationic monomers briefly, then quickly removed and cross-linked using actinic radiation (UV, E-beam, for example). This will result in the cationic monomer chemically bonding to the outer surface of the hydrogel beads or fibers.
Surfactants generally contain both a hydrophilic group and a hydrophobic group. The hydrogel may contain one or more surfactants selected from anionic, nonionic, cationic, ampholytic, amphoteric and zwitterionic surfactants and mixtures thereof. A surfactant that dissociates in water and releases cation and anion is termed ionic. When present, ampholytic, amphoteric and zwitterionic surfactants are generally used in combination with one or more anionic and/or nonionic surfactants. Nonlimiting examples of suitable surfactants and quaternary amines include TRITON X-100, Nonidet P-40 (NP-40), Tergitol, Sarkosyl, Tween, SDS, Igepal, Saponin, CHAPSO, benzalkonium chloride, benzethonium chloride, ‘cetrimide’ (a mixture of dodecyl-, tetradecyl- and hexadecyl-trimethylammoium bromide), cetylpyridium chloride, (meth)acrylamidoalkyltrimethylammonium salts (e.g., 3-methacrylamidopropyltrimethylammonium chloride and 3-acrylamidopropyltrimethylammonium chloride) and (meth)acryloxyalkyltrimethylammonium salts (e.g., 2-acryloxyethyltrimethylammonium chloride, 2-methacryloxyethyltrimethylammonium chloride, 3-methacryloxy-2-hydroxypropyltrimethylammonium chloride, 3-acryloxy-2-hydroxypropyltrimethylammonium chloride, and 2-acryloxyethyltrimethylammonium methyl sulfate). Other suitable monomeric quaternary amino salts include a dimethylalkylammonium group with the alkyl group having 2 to 22 carbon atoms or 2 to 20 carbon atoms. That is, the monomer includes a group of formula —N(CH3)2(CnH2n+1)+ where n is an integer having a value of 2 to 22. Exemplary monomers include, but are not limited to monomers of the following formula
where n is an integer in the range of 2 to 22.
Non-limiting examples of suitable biguanides, which include bis-biguanides, include polyhexamethylene biguanide hydrochloride, p-chlorophenyl biguanide, 4-chloro-benzhydryl biguanide, alexidine, halogenated hexidine such as, but not limited to, chlorhexidine (1,1′-hexamethylene-bis-5-(4-chlorophenyl biguanide), and salts thereof.
Non-limiting examples of suitable phenolics include phenol, salicylic acid, 2-phenylphenol, 4-t-amylphenol, Chloroxylenol, Hexachlorophene, 4-chloro-3,5-dimethylphenol (PCMX), 2-benzyl-4-chlorophenol, triclosan, butylated hydroxytoluene, 2-Isopropyl-5-methyl phenol, 4-Nonylphenol, xylenol, bisphenol A, Orthophenyl phenol, and Phenothiazines, such as chlorpromazine, prochlorperazine and thioridizine.
Non-limiting examples of suitable cytolytic peptides include A-23187 (Calcium ionophore), Dermaseptin, Listerolysin, Ranalexin, Aerolysin, Dermatoxin, Maculatin, Ranateurin, Amphotericin B, Direct lytic factors from animal venoms, Magainin, Rugosin, Ascaphin, Diptheria toxin, Maxymin, Saponin, Aspergillus haemolysin, Distinctin, Melittin, Staphylococcus aureus toxins, (α, β, χ, ), Alamethicin, Esculetin, Metridiolysin, Streptolysin O, Apolipoproteins, Filipin, Nigericin, Streptolysin S, ATP Translocase, Gaegurin, Nystatin, Synexin, Bombinin, GALA, Ocellatin, Surfactin, Brevinin, Gramicidin, P25, Tubulin, Buforin, Helical erythrocyte lysing peptide, Palustrin, Valinomycin, Caerin, Hemolysins, Phospholipases, Vibriolysin, Cereolysin, Ionomycin, Phylloxin, Colicins, KALA, Polyene Antibiotics, Dermadistinctin, LAGA, Polymyxin B.
Non-limiting examples of suitable enzymes include lysozyme, lysostaphin, bacteriophage lysins, achromopeptidase, labiase, mutanolysin, streptolysin, tetanolysin, a-hemolysin, lyticase, lysing enzymes from fungi, cellulase, pectinase, Diselase® Viscozyme® L, pectolyase.
In some embodiments, various combinations of cell extractants can be used in the precursor composition (from which the hydrogel is synthesized) or sorbate (which is loaded into the hydrogel after synthesis of the hydrogel). Any other known cell extractants that are compatible with the precursor compositions or the resulting hydrogels can be used. These include, but are not limited to, chlorhexidine salts such as chlorhexidine gluconate (CHG), parachlorometaxylenol (PCMX), triclosan, hexachlorophene, fatty acid monoesters and monoethers of glycerin and propylene glycol such as glycerol monolaurate, Cetyl Trimethylammonium Bromide (CTAB), glycerol monocaprylate, glycerol monocaprate, propylene glycol monolaurate, propylene glycol monocaprylate, propylene glycol moncaprate, phenols, surfactants and polymers that include a (C12-C22) hydrophobe and a quaternary ammonium group or a protonated tertiary amino group, quaternary amino-containing compounds such as quaternary silanes and polyquaternary amines such as polyhexamethylene biguanide, transition metal ions such as copper containing compounds, zinc containing compounds, and silver containing compounds such as silver metal, silver salts such as silver chloride, silver oxide and silver sulfadiazine, methyl parabens, ethyl parabens, propyl parabens, butyl parabens, octenidene, 2-bromo-2-nitropropane-1,3 diol, or mixtures of any two or more of the foregoing.
Suitable cell extractants also include dialkyl ammonium salts, including N-(n-dodecyl)-diethanolamine; cationic ethoxylated amines, including ‘Genaminox K-10’, Genaminox K-12, ‘Genamin TCL030’, and ‘Genamin C100’; amidines, including propamidine and dibromopropamidine; peptide antibiotics, including polymyxin B and nisin; polyene antibiotics, including nystatin, amphotericin B, and natamycin; imidazoles, including econazole, clotramizole and miconazole; oxidizing agents, including stabilized forms of chlorine and iodine; and the cell extractants described in U.S. Pat. No. 7,422,868, which is incorporated herein by reference in its entirety.
Cell extractants are preferably chosen not to inactivate the detection system (e.g., a detection reagent such as luciferase enzyme) of the present invention. For microbes requiring harsher cell extractants (e.g., ionic detergents etc.), modified detection systems (such as luciferases exhibiting enhanced stability in the presence of these agents, such as those disclosed in U.S. Patent Application Publication No. 2003/0104507, which is hereby incorporated by reference in its entirety) are particularly preferred.
Methods of the present invention provide for the release of an effective amount of cell extractant from a hydrogel to cause the release of biological analytes from a live cell. The present disclosure includes a variety of cell extractants known in the art and each of which may be released form the hydrogel at a different rate and may exert its effect on living cells at a different concentration than the others. The following will provide guidance concerning the factors to be considered in selecting the cell extractant and the in determining an effective amount to include in the hydrogel.
It is known in the art that the efficacy of any cell extractant is determined primarily by two factors—concentration and exposure time. That is, in general, the higher the concentration of a cell extractant, the greater the effect (e.g., permeabilization of the cell membrane and/or release of biological analytes from the cell) it will have on a living cell. Also, at any given concentration of cell extractant, in general, the longer you expose a living cell to the cell extractant, the greater the effect of the cell extractant. Other extrinsic factors such as, for example, pH, co-solvents, ionic strength, and temperature are known in the art to affect the efficacy of certain cell extractant. It is known that these extrinsic factors can be controlled by, for example, temperature controllers, buffers, sample preparation, and the like. These factors, as well as the cell extractant, can also have effects on the detection systems used to detect biological analytes. It is well within the grasp of a person of ordinary skill to perform a few simple experiments to determine an effective amount of cell extractant to produce the articles and perform the methods of the present disclosure. Further guidance is provided in the Examples described herein.
Initial experiments to determine the effect of various concentrations of the cell extractant on the cells and/or the detection system can be performed. Initially, the hydrogel comprising a cell extractant can be screened for its effect on the biological analyte detection system. For example, the hydrogel can be placed into an ATP assay (without bacterial cells) similar to that described herein in Example 19. The assay can be run with solutions of reagent-grade ATP (e.g. from about 0.1 to about 100 picomoles of ATP) and the amount of bioluminescence emitted by the luciferase reaction in the sample with hydrogel can be compared to the amount of bioluminescence emitted by a sample without hydrogel. Preferably, the amount of bioluminescence in the sample with hydrogel is greater than 50% of the amount of bioluminescence in the sample without the hydrogel. More preferably, the amount of bioluminescence in the sample with hydrogel is greater than 90% of the amount of bioluminescence in the sample without the hydrogel. Most preferably, the amount of bioluminescence in the sample with hydrogel is greater than 95% of the amount bioluminescence in the sample without the hydrogel.
Additionally, the effect of the hydrogel on the release of the biological analyte from the cells can be determined experimentally, as described in Example 19. For example, liquid suspensions of cells (e.g., microbial cells such as Staphylococcus aureus) are exposed to relatively broad range of concentrations of a cell extractant (e.g., BARDAC 205M) for a period of time (e.g. up to several minutes) in the present of a detection system to detect biological analytes from a cell (e.g., an ATP detection system comprising luciferin, luciferase, and a buffer at about pH 7.6 to 7.8). The biological analyte is measured periodically, with the first measurement usually performed immediately after the cell extractant is added to the mixture, to determine whether the release of the biological analyte (in this example, ATP) from the cells can be detected. The results can indicate the optimal conditions (i.e., liquid concentration of cell extractant and exposure time) to detect the biological analyte released from the cells. As shown in Table 24, the results can also indicate that, at higher concentrations of cell extractant, the cell extractant may be less effective and/or may interfere with the detection system (i.e., may absorb the light or color generated by the detection reagents).
After the effective amount of cell extractant in liquid mixtures is determined, consideration should be given to the amount of cell extractant to incorporate into the hydrogel by the methods described herein. When the hydrogel comprising a cell extractant forms a liquid mixture (e.g., a sample suspected of containing live cells in an aqueous suspension) the cell extractant diffuses out of the hydrogel until a concentration equilibrium of the cell extractant, between the hydrogel and the liquid, is reached. Without being bound by theory, it can be assumed that, until the equilibrium is reached, a concentration gradient of cell extractant will exist in the liquid, with a higher concentration of extractant present in the portion of the liquid proximal the hydrogel. When the concentration of the cell extractant reaches an effective concentration in a portion of the liquid containing a cell, the cell releases biological analytes. The released biological analytes are thereby available for detection by a detection system.
Achieving an effective concentration of cell extractant in the liquid containing the sample can be controlled by several factors. For example, the amount of cell extractant loaded into the hydrogel can affect final concentration of cell extractant in the liquid at equilibrium. Additionally, the amount of hydrogel and the amount of surface area of the hydrogel in the liquid mixture can affect the rate of release of the cell extractant from the hydrogel and the final concentration of cell extractant in the liquid at equilibrium. Furthermore, the temperature of the aqueous medium can affect the rate at which the hydrogel releases the cell extractant. Other factors, such as the ionic properties and or hydrophobic properties of the cell extractant and the hydrogel may affect the amount of cell extractant released from the hydrogel and the rate at which the cell extractant is released from the hydrogel. All of these factors can be optimized with routine experimentation by a person of ordinary skill to achieve the desired parameters (e.g., manufacturing considerations for the articles and the time-to-result for the methods) for detection of cells in a sample. In general, it is desirable to incorporate at least enough cell extractant into the hydrogel to achieve the effective amount (determined by the experimentation without hydrogels) when the cell extractant reaches equilibrium between the hydrogel and the volume of liquid comprising the sample material. It may be desirable to add a larger amount of cell extractant to the hydrogel (than the amount determined by experimentation without hydrogels) to reduce the amount of time it take for the hydrogel to release an effective amount of cell extractant.
In some embodiments, achieving an effective concentration of cell extractant can comprise using size-selected hydrogel compositions. For example, hydrogel beads can be loaded (e.g., by absorption and/or adsorption) with a cell extractant (e.g., a 50% (w/v) aqueous solution of BARDAC 205M; or a 10%, 17.5%, or 25% (w/v) aqueous solutions of benzalkonium chloride). The hydrogel beads may be size-selected (for example, by sieving the beads through different fine series mesh sizes, such as No. 10 (2.0 mm), No. 12 (1.7 mm), No. 14 (1.4 mm), No. 16 (1.18 mm) and No. 18 (1.0 mm) 8″ Round Test Sieves available from Glison Company, Lewis Center, Ohio) to obtain uniform size beads. The hydrogel beads can be size-selected before and/or after they are loaded with the cell extractant. In some embodiments, the average diameter of the size-selected hydrogel beads may be about 1.0 mm, about 1.18 mm, about 1.4 mm, about 1.7 mm, or about 2.0 mm. In some embodiments, the average diameter of the size-selected hydrogel beads may be less than 1.0 mm. In some embodiments, the average diameter of the size-selected hydrogel beads may be greater than 2.0 mm. Advantageously, the size-selected hydrogel beads can provide better control of the amount of time it takes for the hydrogel to release an effective amount of cell extractant.
In some embodiments, a selected amount of the size-selected hydrogel beads can be used in a detection device. For example, in some embodiments, about 2.5 mg to about 4 mg of hydrogel beads containing BARDAC 205M can be used in a detection device. In some embodiments, about 5 mg to about 10 mg of hydrogel beads containing BARDAC 205M can be used in a detection device. In some embodiments, about 11 mg to about 14 mg of hydrogel beads containing BARDAC 205M can be used in a detection device.
The cell extractant can diffuse into the hydrogel, diffuse out of the hydrogel, or both. The rate of diffusion should be controllable by, for example, varying the polymeric material and the crosslink density, by varying the polar solvent in which the hydrogel is made, by varying the solubility of the cell extractant in the polar solvent in which the hydrogel is made, and by varying the molecular weight of the cell extractant. The rate of diffusion can also be modified by varying the shape, size, and surface topography of the hydrogel.
The hydrogel can be contacted with the liquid sample material either statically, dynamically (i.e., with mixing by vibration, stirring, aeration or compressing, for example), or a combination thereof. Example 16 shows that mixing can effect a faster release of an effective amount of cell extractant from a hydrogel. Example 17 shows that compressing the hydrogel can effect a faster release of an effective amount of cell extractant from hydrogel. Compressing the hydrogel can include, for example, pressing the hydrogel against a surface and/or crushing the hydrogel. Thus, in some embodiments, mixing can advantageously provide a faster release of cell extractant and thereby a faster detection of biological analytes (e.g., from live cells) in a sample. In some embodiments, compressing the hydrogel (e.g., by exerting pressure against the hydrogel using a sample acquisition device such as a swab or a spatula, a carrier (described below) or some other suitable implement) can advantageously provide a faster release of cell extractant and thereby a faster detection of biological analytes in a sample. Additionally, the step of compressing the hydrogel can be performed to accelerate the release of the cell extractant at a time that is convenient for the operator. In some embodiments, static contact can delay the release of an effective amount of cell extractant and thereby provide additional time for the operator to carry out other procedures (e.g., reagent additions, instrument calibration, and/or specimen transport) before detecting the biological analytes. In some embodiments, it may be advantageous to hold the mixture statically until a first biological analyte measurement is taken and then dynamically mix the sample to reduce the time necessary to release an effective amount of cell extractant.
It is fully anticipated that the most preferred concentration(s) or concentration range(s) functional in the methods of the invention will vary for different microbes and for different cell extractants and may be empirically determined using the methods described herein or commonly known to those skilled in the art.
Articles and methods of the present disclosure provide for the detection of biological analytes in a sample. In some embodiments, the articles and methods provide for the detection of biological analytes from live cells in a sample. In certain preferred embodiments, the articles and methods provide for the detection of live microbial cells in a sample. In certain preferred embodiments, the articles and methods provide for the detection of live bacterial cells in a sample.
The term “sample” as used herein, is used in its broadest sense. A sample is a composition suspected of containing a biological analyte (e.g., ATP) that is analyzed using the invention. While often a sample is known to contain or suspected of containing a cell or a population of cells, optionally in a growth media, or a cell lysate, a sample may also be a solid surface, (e.g., a swab, membrane, filter, particle), suspected of containing an attached cell or population of cells. It is contemplated that for such a solid sample, an aqueous sample is made by contacting the solid with a liquid (e.g., an aqueous solution) which can be mixed with hydrogels of the present. Filtration of the sample is desirable in some cases to generate a sample, e.g., in testing a liquid or gaseous sample by a process of the invention. Filtration is preferred when a sample is taken from a large volume of a dilute gas or liquid. The filtrate can be contacted with hydrogels of the present disclosure, for example after the filtrate has been suspended in a liquid.
Suitable samples include samples of solid materials (e.g., particulates, filters), semisolid materials (e.g., a gel, a liquid suspension of solids, or a slurry), a liquid, or combinations thereof. Suitable samples further include surface residues comprising solids, liquids, or combinations thereof. Non-limiting examples of surface residues include residues from environmental surfaces (e.g., floors, walls, ceilings, fomites, equipment, water, and water containers, air filters), food surfaces (e.g., vegetable, fruit, and meat surfaces), food processing surfaces (e.g., food processing equipment and cutting boards), and clinical surfaces (e.g., tissue samples, skin and mucous membranes).
The collection of sample materials, including surface residues, for the detection of biological analytes is known in the art. Various sample acquisition devices, including spatulas, sponges, swabs and the like have been described. The present disclosure provides sample acquisition devices with unique features and utility, as described herein.
Turning now to the Figures,
The sample acquisition device 130 further comprises an elongated shaft 134 and a tip 139. In some embodiments, the shaft 134 can be hollow. The shaft 134 comprises a tip 139, positioned near the end of the shaft 134 opposite the handle 131. The tip 139 can be used to collect sample material and can be constructed from porous materials, such as fibers (e.g., rayon or Dacron fibers) or foams (e.g., polyurethane foam) which can be affixed to the shaft 134. In some embodiments, the tip 139 can be a molded tip as described in U.S. Patent Application No. 61/029,063, filed on Dec. 5, 2007 and entitled, “SAMPLE ACQUISITION DEVICE”, which is incorporated herein by reference in its entirety. The construction of sample acquisition devices 130 is known in the art and can be found, for example, in U.S. Pat. No. 5,266,266, which is incorporated herein by reference in their entirety.
Optionally, the sample acquisition device 130 can further comprise a hydrogel 140 comprising a cell extractant. In some embodiments, the hydrogel 140 is positioned in or on the sample acquisition device 130 at a location other than the tip 139 that is used to collect the sample (e.g., on the shaft 134, as shown in
In use, the tip 139 of a sample acquisition device 130 is contacted with a sample material (e.g., a solid, a semisolid, a liquid suspension, a slurry, a liquid, a surface, and the like) to obtain a sample suspected of containing cells. The sample acquisition device 130 can be used to transfer the sample to a detection system as described herein.
In use, sample acquisition device 230 can be used to contact surfaces, preferably dry surfaces, to obtain sample material. After the sample is obtained, the tip 239 of the sample acquisition device 230 is moistened with a liquid (e.g. water or a buffer; optionally, including a detection reagent such as an enzyme and/or an enzyme substrate), thereby permitting an effective amount of the cell extractant to be released from the hydrogel 240 and to contact the sample material. The release of an effective amount of cell extractant from hydrogel 240 permits the sample acquisition device 230 to be used in methods to detect biological analytes from live cells as described herein.
Another embodiment (not shown) of a sample acquisition device including a hydrogel comprising a cell extractant can be derived from the “Specimen Test Unit” disclosed by Nason in U.S. Pat. No. 5,266,266 (hereinafter, referred to as the “Nason patent”). In particular, referring to FIGS. 7-9 of the Nason patent, the handle of the sample acquisition devices described herein can be modified to embody Nason's functional elements of the housing base 14 (which forms reagent chamber 36) and the seal fitting 48, which includes central dispense passage 50 (optional, with housing cap 30) connected to the hollow swab shaft 22. The central passage 50 of the seal fitting 48 can be closed by a break-off nib 52 in the form of an extended rod segment 54 connected to the seal fitting 48 at the inboard end of the passage 50 via a reduced diameter score 56. Thus, in one embodiment of the present disclosure, the sample acquisition device handle comprises a reagent chamber, as described by Nason. The reagent chamber located in the handle of the sample acquisition device of this embodiment includes hydrogel particles (e.g., beads) comprising a cell extractant. Thus, the sample acquisition device of this embodiment provides an enclosure (reagent chamber 36) containing the hydrogel. In this embodiment, the hydrogel particles are not suspended in a liquid medium than causes the release of the cell extractant from the hydrogel. The hydrogel particles are proportioned and shaped to allow free passage of the individual particles into and through the central passage 50 and the hollow shaft 22.
In use, the sample acquisition device comprising a handle including a reagent chamber can be used to obtain a sample as described herein. If the sample is a liquid, the break-off nib 52 can be actuated, as described in the Nason patent, enabling the passage of the hydrogel through the shaft to contact the liquid sample in the swab tip, thereby forming a liquid mixture comprising the sample and the hydrogel. The liquid mixture comprising the sample and the hydrogel can be used for the detection of a biological analyte associated with a live cell, as described herein. If the sample is a solid or semi-solid, the tip of the sample acquisition device can be contacted or submersed in a liquid solution and the break-off nib 52 can be actuated, as described in the Nason patent, enabling the passage of the hydrogel through the shaft to contact the liquid sample in the swab tip, thereby forming a liquid mixture comprising the sample and the hydrogel. The liquid mixture comprising the sample and the hydrogel can be used for the detection of a biological analyte associated with a live cell, as described herein.
In
In some embodiments (not shown), the hydrogel 340 can be coated onto a solid substrate (e.g., the wall 324 of the housing 320). Nonlimiting examples of other suitable solid substrates (not shown) onto which hydrogels 340 of the present disclosure can be coated include a polymeric film, a fiber, a nonwoven, a ceramic particle, paper, and a polymeric bead. Solid substrates can be coated with hydrogel 340 by a variety of processes including; for example, dip coating, knife coating, curtain coating, spraying, kiss coating, gravure coating, offset gravure coating, and/or printing methods such as screen printing and inkjet printing can be used to apply the hydrogel composition onto the substrate in a pattern if desired. The choice of the coating process will be influenced by the shape and dimensions of the solid substrate and it is within the grasp of a person of ordinary skill in the appropriate art to recognize the suitable process for coating any given solid substrate.
It should be recognized that in this and all other embodiments (for example, the illustrated embodiments of
The wall 324 of the housing 320 can be cylindrical, for example. It will be appreciated that other useful geometries, some including a plurality of walls 324, are possible and within the grasp of one of ordinary skill in the appropriate art. The housing 320 can be constructed from a variety of materials such as plastic (e.g., polypropylene, polyethylene, polycarbonate) or glass. Preferably, at least a portion of the housing 320 is constructed from materials that have optical properties that allow the transmission of light (e.g., visible light). Suitable materials are well known in devices used for biochemical assays such as ATP tests, for example.
Optionally, housing 320 can comprise a cap (not shown) that can be shaped and dimensioned to cover the opening 322 of the housing 320. It should be recognized that other housings (for example, housings 420 and 520 as shown in
In some embodiments, the housing 320 can be used in conjunction with a sample acquisition device (not shown). Optionally, the sample acquisition device may comprise a hydrogel, such as, for example, sample acquisition devices 130 or 230 shown in
The housing 320 can be used in methods to detect live cells in a sample. During use, the operator can form a liquid (e.g., an aqueous liquid or aqueous solutions containing glycols and/or alcohols) mixture in the housing 320, the mixture comprising a liquid sample and the hydrogel 340. In some embodiments, the mixture can further comprise a detection reagent. The liquid mixture comprising the sample and the hydrogel 440 can be used for the detection of a biological analyte associated with a live microorganism.
The frangible seal 460 forms a barrier between the upper compartment 426 (which includes the opening 422 of the housing 420) and the reaction well 428. In some embodiments, the frangible seal 460 forms a water-resistant barrier. The frangible seal 460 can be constructed from a variety of frangible materials including, for example polymer films, metal-coated polymer films, metal foils, dissolvable films (e.g., films made of low molecular weight polyvinyl alcohol or hydroxypropyl cellulose (HPC) and combinations thereof.
Frangible seal 460 may be connected to the wall 424 of the housing 420 using a variety of techniques. Suitable techniques for attaching a frangible seal 460 to a wall 424 include, but are not limited to, ultrasonic welding, any thermal bonding technique (e.g., heat and/or pressure applied to melt a portion of the wall 424, the frangible seal 460, or both), adhesive bonding, stapling, and stitching. In one desired embodiment of the present invention, the frangible seal 460 is attached to the wall 424 using an ultrasonic welding process.
The housing 420 can be used in methods to detect cells in a sample. Methods of the present disclosure include the formation of a liquid mixture comprising the sample material and the hydrogel 440 and include the detection of a biological analyte, as described herein.
If the sample is a liquid sample (e.g., water, juice, milk, meat juice, vegetable wash, food extracts, body fluids and secretions, saliva, wound exudate, and blood), the liquid sample can be transferred (e.g., poured or pipetted) directly into the upper chamber 426. A detection reagent can be added to the sample before the sample is transferred to the housing 420. A detection reagent can be added to the sample after the sample is transferred to the housing 420. A detection reagent can be added to the sample while the sample is transferred to the housing 420. The frangible seal 460 can be ruptured (e.g., by piercing it with a pipette tip or a sample acquisition device) before the liquid sample is transferred to the housing 420. The frangible seal 460 can be ruptured after the liquid sample is transferred to the housing 420. The frangible seal 460 can be ruptured while the liquid sample is transferred to the housing 420. When the liquid sample is in the housing 420 and the frangible seal is ruptured, a liquid mixture comprising the sample and the hydrogel 440 is formed. The liquid mixture comprising the sample and the hydrogel 440 can be used for the detection of a biological analyte associated with a live microorganism.
If the sample is a solid sample (e.g., powder, particulates, semi-solids, residue collected on a sample acquisition device, air filter), the housing 420 can advantageously be used as a vessel in which the sample can be mixed with a liquid suspending medium such as, for example, water or a buffer. Preferably, the liquid suspending medium is substantially free of microorganisms. More preferably, the liquid suspending medium is sterile. Before, after or during the process of mixing the solid sample with the liquid suspending medium, a detection reagent can be added to the liquid suspending medium. Either before, after, or during the process of mixing the solid sample with the liquid suspending medium, the frangible seal 460 can be ruptured (e.g., by piercing with a pipette tip or a swab), thus forming a liquid mixture comprising the sample and the hydrogel 440 comprising a cell extractant. The liquid mixture comprising the sample and the hydrogel 440 can be used in a method for the detection of a biological analyte associated with a live cell.
In
The reagent well 528 of housing 520 comprises a detection reagent 570. Optionally, the detection reagent 570 can comprise a detection reagent (i.e., a detection reagent may be dissolved and/or suspended in the detection reagent 570). In other embodiments (not shown), the reagent well 528 can comprise a dry detection reagent (e.g., a powder, particles, microparticles, a tablet, a pellet, and the like) instead of the detection reagent 570.
The housing 520 can be used in methods to detect cells in a sample. Methods of the present disclosure include the formation of a liquid mixture comprising the sample material and the hydrogel 440 and include the detection of a biological analyte, as described herein.
If the sample is a liquid sample (e.g., water, juice, milk, meat juice, vegetable wash, food extracts, body fluids and secretions, saliva, wound exudate, and blood), the liquid sample can be transferred (e.g., poured or pipetted) directly into the upper compartment 526, thus forming a liquid mixture comprising the sample and the hydrogel 540. Before, after or during the transfer of the sample into the housing 520, a detection reagent can be added to the liquid sample. Before, after, or during the transfer of the liquid sample to the housing 520, the frangible seal 560 can be ruptured (e.g., by piercing with a pipette tip or a swab). The liquid mixture comprising the sample and the hydrogel 540 can be used for the detection of a biological analyte associated with a live microorganism before and/or after the frangible seal 560 is ruptured.
If the sample is a solid sample (e.g., powder, particulates, semi-solids, residue collected on a sample acquisition device), the housing 520 can advantageously be used as a vessel in which the sample can be mixed with a liquid suspending medium such as, for example, water or a buffer. Preferably, the liquid suspending medium is substantially free of microorganisms. More preferably, the liquid suspending medium is sterile.
Mixing the solid sample with a liquid suspending medium forms a liquid mixture comprising the sample and the hydrogel 540. Before, after or during the process of mixing the solid sample with the liquid suspending medium, a detection reagent can be added to the liquid suspending medium. Before, after, or during the process of mixing the solid sample with the liquid suspending medium, the frangible seal 560 can be ruptured (e.g., by piercing with a pipette tip or a swab). The liquid mixture comprising the sample and the hydrogel 540 can be used for the detection of a biological analyte associated with a live microorganism, as described herein.
The sample acquisition device 630 comprises a handle 631 which can be grasped by the operator while collecting a sample. The sample acquisition device 630 is shown in
In use, the tip 739 of a sample acquisition device 730 is contacted with a sample material (e.g., a solid, a semisolid, a liquid suspension, a slurry, a liquid, a surface, and the like), as described above. After collecting the sample, the sample acquisition device 730 is reinserted into the housing 720 and the handle is urged into the housing 720, as described above, thereby causing the tip 739 to pass through frangible seals 760a and 760b and into the detection reagent in the reaction well 728. As the tip 739 passes through frangible seals 760a and 760b, the hydrogel 740 is also moved into the detection reagent 770 in the reaction well 728. This process forms a liquid mixture that includes a sample and a hydrogel 740. The liquid mixture comprising the sample and the hydrogel 40 can be used for the detection of a biological analyte associated with a live microorganism, as described herein.
In use, the sample acquisition device 830 is removed from the detection device 810 and a sample is collected as described herein on the tip 839. The sample acquisition device 830 is reinserted into the housing 820 and the handle 831 is urged into the housing 820, as described for the detection device in
Methods of Detecting Biological analytes from Live Cells:
Methods of the present disclosure include methods for the detection of biological analytes that are released from live cells including, for example, live microorganisms, after exposure to an effective amount of cell extractant.
The detection of the biological analytes involves the use of a detection system. Detection systems for certain biological analytes such as a nucleotide (e.g., ATP), a polynucleotide (e.g., DNA or RNA) or an enzyme (e.g., NADH dehydrogenase or adenylate kinase) are known in the art and can be used according to the present disclosure. Methods of the present disclosure include known detections systems for detecting a biological analyte. Preferably, the accuracy and sensitivity of the detection system is not significantly reduced by the cell extractant. More preferably, the detection system comprises a homogeneous assay.
In some embodiments, the detection system comprises a detection reagent. Detection reagents include, for example, dyes, enzymes, enzyme substrates, binding partners (e.g., an antibody, a monoclonal antibody, a lectin, a receptor), and/or cofactors. In some embodiments, the detection system comprises an instrument.
Nonlimiting examples of detection instruments include a spectrophotometer, a luminometer, a plate reader, a thermocycler, an incubator.
Detection systems are known in the art and can be used to detect biological analytes colorimetrically (i.e., by the absorbance and/or scattering of light), fluorescently, or lumimetrically. Examples of the detection of biomolecules by luminescence are described by F. Gorus and E. Schram (Applications of bio- and chemiluminescence in the clinical laboratory, 1979, Clin. Chem. 25:512-519).
An example of a biological analyte detection system is an ATP detection system. The ATP detection system can comprise an enzyme (e.g., luciferase) and an enzyme substrate (e.g., luciferin). The ATP detection system can further comprise a luminometer. In some embodiments, the luminometer can comprise a bench top luminometer, such as the FB-12 single tube luminometer (Berthold Detection Systems USA, Oak Ridge, Tenn.). In some embodiments, the luminometer can comprise a handheld luminometer, such as the NG Luminometer, UNG2 (3M Company, Bridgend, U.K.).
Methods of the present disclosure include the formation of a liquid mixture comprising a sample suspected of containing live cells and a hydrogel comprising a cell extractant. Methods of the present disclosure further include detecting a biological analyte. Detecting a biological analyte can further comprise quantitating the amount of biological analyte in the sample.
In some embodiments, detecting the biological analyte can comprise detecting the analyte directly in a vessel (e.g., a tube, a multi-well plate, and the like) in which the liquid mixture comprising the sample and the hydrogel comprising a cell extractant is formed. In some embodiments, detecting the biological analyte can comprise transferring at least a portion of the liquid mixture to a container other than the vessel in which the liquid mixture comprising the sample and the hydrogel comprising a cell extractant is formed. In some embodiments, detecting the biological analyte may comprise one or more sample preparation processes, such as pH adjustment, dilution, filtration, centrifugation, extraction, and the like.
In some embodiments, the biological analyte is detected at a single time point. In some embodiments, the biological analyte is detected at two or more time points. When the biological analyte is detected at two or more time points, the amount of biological analyte detected at a first time (e.g., before an effective amount of cell extractant is released from a hydrogel to effect the release of biological analytes from live cells in at least a portion of the sample) point can be compared to the amount of biological analyte detected at a second time point (e.g., after an effective amount of cell extractant is released from a hydrogel to effect the release of biological analytes from live cells in at least a portion of the sample). In some embodiments, the measurement of the biological analyte at one or more time points is performed by an instrument with a processor. In certain preferred embodiments, comparing the amount of biological analyte at a first time point with the amount of biological analyte at a second time point is performed by the processor.
For example, the operator measures the amount of biological analyte in the sample after the liquid mixture including the sample and the hydrogel comprising a cell extractant is formed. The amount of biological analyte in this first measurement (T0) can indicate the presence of “free” (i.e. acellular) biological analyte and/or biological analyte from nonviable cells in the sample. In some embodiments, the first measurement can be made immediately (e.g., about 1 second) after the liquid mixture including the sample and the hydrogel comprising a cell extractant is formed. In some embodiments, the first measurement can be at least about 5 seconds, at least about 10 seconds, at least about 20 seconds, at least about 30 seconds, at least about 40 seconds, at least about 60 seconds, at least about 80 seconds, at least about 100 seconds, at least about 120 seconds, at least about 150 seconds, at least about 180 seconds, at least about 240 seconds, at least about 5 minutes, at least about 10 minutes, at least about 20 minutes after the liquid mixture including the sample and the hydrogel comprising a cell extractant is formed. These times are exemplary and include only the time up to that the detection of a biological analyte is initiated. Initiating the detection of a biological analyte may include diluting the sample and/or adding a reagent to inhibit the activity of the cell extractant. It will be recognized that certain detection systems (e.g., nucleic acid amplification or ELISA) can generally take several minutes to several hours to complete.
The operator allows the sample to contact the hydrogel comprising the cell extractant for a period of time after the first measurement of biological analyte has been made. After the sample has contacted the hydrogel for a period of time, a second measurement of the biological analyte is made. In some embodiments, the second measurement can be made up to about 0.5 seconds, up to about 1 second, up to about 5 seconds, up to about 10 seconds, up to about 20 seconds, up to about 30 seconds, up to about 40 seconds, up to about 60 seconds, up to about 90 seconds, up to about 120 seconds, up to about 180 seconds, about 300 seconds, at least about 10 minutes, at least about 20 minutes, at least about 60 minutes or longer after the first measurement of the biological analyte. These times are exemplary and include only the interval of time from which the first measurement for detecting the biological analyte is initiated and the time at which the second measurement for detecting the biological analyte is initiated. Initiating the detection of a biological analyte may include diluting the sample and/or adding a reagent to inhibit the activity of the cell extractant.
Preferably, the first measurement of a biological analyte is made about 1 seconds to about 240 seconds after the liquid mixture including the sample and the hydrogel comprising a cell extractant is formed and the second measurement, which is made after the first measurement, is made about 1.5 seconds to about 540 seconds after the liquid mixture is formed. More preferably, the first measurement of a biological analyte is made about 1 second to about 180 seconds after the liquid mixture is formed and the second measurement, which is made after the first measurement, is made about 1.5 seconds to about 120 seconds after the liquid mixture is formed. Most preferably, the first measurement of a biological analyte is made about 1 second to about 5 seconds after the liquid mixture is formed and the second measurement, which is made after the first measurement, is made about 1.5 seconds to about 10 seconds after the liquid mixture is formed.
The operator compares the amount of a biological analyte detected in the first measurement to the amount of biological analyte detected in the second measurement. An increase in the amount of biological analyte detected in the second measurement is indicative of the presence of one or more live cells in the sample.
In certain methods, it may be desirable to detect the presence of live somatic cells (e.g., nonmicrobial cells). In these embodiments, the hydrogel comprises a cell extractant that selectively releases biological analytes from somatic cells. Nonlimiting examples of somatic cell extractants include nonionic detergents, such as non-ionic ethoxylated alkylphenols, including but not limited to the ethoxylated octylphenol Triton X-100 (TX-100) and other ethoxylated alkylphenols; betaine detergents, such as carboxypropylbetaine (CB-18), NP-40, TWEEN, Tergitol, Igepal, commercially available M-NRS (Celsis, Chicago, Ill.), M-PER (Pierce, Rockford, Ill.), CelLytic M (Sigma Aldrich). Cell extractants are preferably chosen not to inactivate the analyte and its detection reagents.
In certain methods, it may be desirable to detect the presence of live microbial cells. In these embodiments, the hydrogel can comprise a cell extractant that selectively releases biological analytes from microbial cells. Nonlimiting examples of microbial cell extractants include quaternary ammonium compounds, including benzalkonium chloride, benzethonium chloride, ‘cetrimide’ (a mixture of dodecyl-, tetradecyl- and hexadecyl-trimethylammoium bromide), cetylpyridium chloride; amines, such as triethylamine (TEA) and triethanolamine (TeolA); bis-Biguanides, including chlorhexidine, alexidine and polyhexamethylene biguanide Dialkyl ammonium salts, including N-(n-dodecyl)-diethanolamine, antibiotics, such as polymyxin B (e.g., polymyxin B1 and polymyxin B2), polymyxin-beta-nonapeptide (PMBN); alkylglucoside or alkylthioglucoside, such as Octyl-β-D-1-thioglucopyranoside (see U.S. Pat. No. 6,174,704 herein incorporated by reference in its entirety); nonionic detergents, such as non-ionic ethoxylated alkylphenols, including but not limited to the ethoxylated octylphenol Triton X-100 (TX-100) and other ethoxylated alkylphenols; betaine detergents, such as carboxypropylbetaine (CB-18); and cationic, antibacterial, pore forming, membrane-active, and/or cell wall-active polymers, such as polylysine, nisin, magainin, melittin, phopholipase A2, phospholipase A2 activating peptide (PLAP); bacteriophage; and the like. See e.g., Morbe et al., Microbiol. Res. (1997) vol. 152, pp. 385-394, and U.S. Pat. No. 4,303,752 disclosing ionic surface active compounds which are incorporated herein by reference in their entirety. Cell extractants are preferably chosen not to inactivate the biological analyte and/or a detection reagent used to detect the biological analyte.
In certain alternative methods to detect the presence of live microbial cells in a sample, the sample can be pretreated with a somatic cell extractant for a period of time (e.g., the sample is contacted with a somatic cell extractant for a sufficient period of time to extract somatic cells before a liquid mixture including the sample and a hydrogel comprising a microbial cell extractant is formed). In the alternative embodiment, the amount of biological analyte detected at the first measurement will include any biological analyte that was released by the somatic cells and the amount of additional biological analyte, if any, detected in the second measurement will include biological analyte from live microbial cells in the sample.
The present invention has now been described with reference to several specific embodiments foreseen by the inventor for which enabling descriptions are available. Insubstantial modifications of the invention, including modifications not presently foreseen, may nonetheless constitute equivalents thereto. Thus, the scope of the present invention should not be limited by the details and structures described herein, but rather solely by the following claims, and equivalents thereto.
Beads were made as described in example 1 of International Patent Publication No. WO 2007/146722, in which the deionized water was replaced with the desired loading solution. A homogeneous precursor composition was prepared by mixing 40 grams of 20-mole ethoxylated trimethylolpropane triacrylate (EO20-TMPTA) (SR415 from Sartomer, Exeter, Pa.), 60 grams deionized (DI) water, and 0.8 grams photoinitiator (IRGACURE 2959 from Ciba Specialty Chemicals, Tarrytown, N.Y.). The precursor composition was poured into a funnel such that the precursor composition exited the funnel through a 2.0 millimeter diameter orifice. Precursor composition fell along the vertical axis of a 0.91 meter long, 51 millimeter diameter quartz tube that extended through a UV exposure zone defined by a light shield and a 240 W/cm irradiator (available from Fusion UV Systems, Gaithersburg, Md.) equipped with a 25-cm long “H” bulb coupled to an integrated back reflector such that the bulb orientation was parallel to falling precursor composition. Below the irradiator, polymeric beads were obtained. The entire process was operated under ambient conditions
The BARDAC 205 M and 208M (blends of quaternary ammonium compounds and alkyl dimethyl benzyl ammonium chloride; Lonza Group Ltd., Valais, Switzerland) hydrogel beads were prepared by mixing 20 grams of EO20-TMPTA, 30 grams of the BARDAC 205M or 208M solution and 0.4 grams of Irgacure 2959 and exposed to UV light to prepare beads as described in example 1 in International Patent Publication No. WO 2007/146722. The beads were prepared using 12.5% and 25% (w/v) solutions of BARDAC 205M and 208M in deionized water. After recovering the beads, they were stored in a jar at room temperature. The beads were designated as shown below:
Polymeric beads with cationic monomers were prepared as described in Example 30 to 34 of International patent WO2007/146722. The precursor composition used for making beads is indicated in Table 1. The various components of the precursor compositions were stirred together in an amber jar until the antimicrobial monomer dissolved.
DMAEMA-C8Br was formed within three-neck round bottom reaction flask that was fitted with a mechanical stirrer, temperature probe and a condenser. The reaction flask was charged with 234 parts of dimethylaminoethylmethacryalte, 617 part of acetone, 500 parts 1-bromoethane, and 0.5 parts of BHT antioxidant. The mixture was stirred for 24 hours at 35° C. At this point, the reaction mixture was cooled to room temperature and a slightly yellow clear solution was obtained. The solution was transferred to a round bottom flask and acetone was removed by rotary evaporation under vacuum at 40° C. The resulting solids were washed with cold ethyl acetate and dried under vacuum at 40° C. DMAEMA-C10Br and DMAEMA-C12Br were formed using a similar procedure in which the 1-bromooctane was replaced by 1-bromodecane and 1-bromododecane, respectively.
The 3-(acryloamidopropyl)trimethylammonium chloride was obtained by Tokyo Kasei Kogyo Ltd (Japan). Ageflex FA-1080MC was obtained from Ciba Specialty Chemicals.
Hydrogel beads containing luciferin were made similarly by mixing 20 parts of EO20-TMPTA with 30 parts of luciferin (2 mg in 30 ml of 14 mM of phosphate buffer, pH 6.4) and 0.4 parts photoinitiator (IRGACURE 2959) and exposed to UV light to prepare beads as described in example 1 in International Patent Publication No. WO 2007/146722 A1. The beads were then stored in a jar at 4° C. and designated as Luciferin-1s.
Hydrogel beads containing luciferase were made by mixing 20 parts of polymer with 30 parts of luciferase (150 μl of 6.8 mg/ml in 30 ml of 14 mM of phosphate buffer, pH 6.4) and 0.4 parts photoinitiator (IRGACURE 2959) and exposed to UV light to prepare beads as described in example 1 in International Patent Publication No. WO 2007/146722 A1. The beads were then stored in a jar at 4° C. and designated as Luciferase-1s.
Hydrogel beads were prepared as described in example 1 International Patent Publication No. WO 2007/146722. Active beads were prepared by drying as described in example 19 and then soaking in active solution as described in example 23 of International Patent Publication No. WO 2007/146722. One gram of beads was dried at 60° C. for 2 h to remove water from the beads. The dried beads were soaked in 2 grams of BARDAC 205M for at least 3 hrs to overnight at room temperature. After soaking, the beads were poured into a Buchner funnel to drain the beads and then rinsed with 10 to 20 ml of distilled water. The excess water was removed from the surface of the beads by blotting them with a paper towel. The beads were prepared using 10%, 12.5%, 20%, 25%, 50% and 100% (w/v) aqueous solutions of BARDAC 205M, 5%, 10%, 12.5%, 25% and 50% solutions of 208M, 20% solution of Triclosan (Ciba Specialty Chemicals,), 1% and 5% solutions of chlorohexidine digluconate (CHG; Sigma Aldrich, St. Louis, Mo.) and 0.25% and 0.5% solutions of Cetyltrimethylammoniumbromide (CTAB; Sigma Aldrich). The beads were then stored in a jar at room temperature. The beads were designated as shown below.
Hydrogel beads of VANTOCIL (Arch Chemicals, Norwalk, Conn.), CARBOSHIELD (Lonza) and a blend of Vantocil and CarboShield were prepared similarly. The dried hydrogel beads were soaked in 50% solution (in distilled water) of VANTOCIL or 100% solution of CARBOSHIELD 1000 or 1:1 mixture of 50% Vantocil and 100% Carboshield solutions. The beads with the mixture of VANTOCIL and CARBOSHIELD resulted in 25% Vantocil and 50% Carboshield beads. The beads were then stored in a jar at room temperature and designated as follows
Polymeric fibers were made as described in example 1 of US Patent Application Publication No. US2008/207794. A homogeneous precursor composition was prepared that contained about 500 grams of 40 wt-% 20-mole EO20-TMPTA (SR415 from Sartomer) and 1 wt-% photoinitiator (IRGACURE 2959 from Ciba Specialty Chemicals) in deionized water. The precursor composition was processed as described in example 1 of US Patent Application Publication No. US2008/207794 to make the polymeric fibers.
One gram of fibers was dried at 60° C. for 2 h to remove water from the fibers. The dried fibers were soaked in 2 grams of 50% solution of BARDAC 205M for at least 3 hrs to overnight at room temperature. After soaking, the fibers were poured into a Buchner funnel to drain the fibers and then rinsed with 10 to 20 ml of distilled water. The excess water was removed from the surface of the fibers by blotting them with a paper towel. The fibers were then stored in a jar at room temperature.
Hydrogel beads (1× gram) were dried at 60° C. for 2 h and soaked in 2× grams of luciferin solution (2 mg in 30 ml of 14 mM of phosphate buffer, pH6.4) for at least 16 h at 4° C. After soaking, the beads were poured into a Buchner funnel to drain the beads and then rinsed with distilled water. The excess water was removed from the surface of the beads by blotting them with a paper towel. The beads were then stored in a jar at 4° C. and designated as Lucifein-1p
Hydrogel beads (1× gram) were dried at 60 C for 2 h and soaked in 2× grams of luciferase solution (150 μl of 6.8 mg/ml luciferase in 30 ml of 14 mM of phosphate buffer, pH6.4) for at least 16 h at 4° C. After soaking, the beads were poured into a Buchner funnel to drain the beads and then rinsed with distilled water. The excess water was removed from the surface of the beads by blotting them with a paper towel. Hydrogel beads containing lysozyme or lysostaphin were prepared similarly by soaking in 2× grams of 50 mM TRIS pH 8.0 solution containing 0.5 mg/ml lysozyme or 50 μg/ml lysostaphin. The beads were then stored in a jar at 4° C. and designated as Luciferase-1p, Lysozyme-1p and Lysostaphin-1p.
Hydrogel beads were prepared as described in example 1 International Patent Publication No. WO 2007/146722. The hydrogel beads were sieved through different fine series mesh sizes No. 10 (2.0 mm), No. 12 (1.7 mm), No. 14 (1.4 mm), No. 16 (1.18 mm) and No. 18 (1.0 mm) (8″ Round Test Sieves, Glison Company, Lewis Center, Ohio) to obtain uniform size beads. The beads were sieved using a Model AS200 shaker (Retsch, Inc., Newtown, Pa.) set at 1.00 mm/“g” for a 15 second interval. Total shaking time for each batch was 10 minutes. Active beads from various size selected beads were prepared as described in Preparative Example 5. Some beads were prepared using 50% (w/v) aqueous solutions of BARDAC 205M. Other beads were prepared using 10%, 17.5%, or 25% (w/v) aqueous solutions of bezalkonium chloride (BAC; Alfa Aesar, Ward Hill, Mass.). The beads were then stored in an amber jar at room temperature. The beads were designated as shown below.
The microbial species used in the examples (Table 2) were obtained from ATCC (Manassas, Va.). 3M™ Clean-Trace™ Surface ATP system and NG Luminometer UNG2 were obtained from 3M Company (St. Paul, Minn.). Rayon-tipped applicators were obtained from Puritan Medical Products (Guilford, Me.). Beads containing BARDAC 205M were made according to Preparative Example 5.
Candida albicans
Candida albicans
Corynebacterium xerosis
Enterococcus faecalis
Enterococcus faecalis
Enterococcus faecium
Enterococcus faecium
Escherichia coli
Kocuria kristinae
Micrococcus luteus
Pseudomonas aeruginosa
Salmonella enterica subsp. enterica
Staphylococcus aureus
Staphylococcus epidermidis
Streptococcus pneumoniae
Pure cultures of the bacterial strains were inoculated into tryptic soy broth and were grown overnight at 37° C. Swabs from some of the Clean-Trace surface ATP hygiene tests, which include microbial cell extractants, were replaced with sterile rayon-tipped applicators, which do not include microbial cell extractants. Various amounts (approximately 106, 107 and 108, colony-forming units (CFU) per milliliter, respectively) of bacteria were suspended in Butterfield's buffer and cell suspensions were added directly to the Clean-Trace surface ATP swabs (10 microliters) or the rayon-tipped applicators (100 microliters). Each swab or applicator was activated by pushing it into the reagent chamber according to the manufacturer's instructions. The test unit was immediately inserted into the reading chamber of a NG Luminometer, UNG2 and an initial (T0) measurement of Relative Light Units (RLUs) was recorded. One BARDAC 205M-containing hydrogel bead, 205M-1p, was added to some of the test units and subsequent RLU measurements were recorded at 20 sec interval using the “Unplanned Testing” mode of the luminometer until the number of RLUs reached a plateau. The data were downloaded using the software provided with the NG luminometer. 205M-1p beads were able to lyse bacteria and release ATP from cells, as shown by the data in Table 3. The relative light units (RLU) increased over time with BARDAC 205M beads, while without beads the background did not increase. Experiments using the Clean-Trace surface ATP swabs showed that the RLU reached maximum within 20 seconds and then began to decrease.
S. aureus
E. coli
A S. aureus overnight culture was prepared as described in Example 1. Hydrogel beads containing VANTOCIL and/or CARBOSHIELD were prepared as described in Preparative Example 5. The luciferase/luciferin liquid reagent solution (300 μl) was removed from Clean-Trace surface ATP hygiene test units and transferred to 1.5 ml microfuge tubes. The bacterial culture was diluted to 107 CFU/ml in Butterfield's buffer and 10 microliters of the diluted suspension were added directly to individual microfuge tubes (i.e., approximately 105 CFU per tube). Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (FB-12 single tube luminometer, Berthold Detection Systems USA, Oak Ridge, Tenn.) and an initial (T0) measurement of RLUs was recorded. The initial (and all subsequent luminescence measurements) were obtained from the luminometer using FB 12 Sirius PC software that was provided with the luminometer. The light signal was integrated for 1 second and the results are expressed in RLU/sec.
A hydrogel bead containing VANTOCIL (Van-1p), CARBOSHIELD (Carbo-1p), or both VANTOCIL and CARBOSHIELD (Van-Carbo-1p) was added to individual tubes and RLU measurements were recorded at 10 sec intervals until the number of RLUs reached a plateau (Table 3).
The hydrogel beads, containing individual disinfectants or a disinfectant mixture, extracted ATP from the S. aureus cells and the ATP reacted with the ATP-detection reagents of the Clean-Trace surface ATP units, as shown in Table 4. The relative light units (RLU) increased over time in the tubes that received the disinfectant-loaded beads, while the tubes without beads did not show a significant increase in RLU over time.
S. aureus and E. coli overnight cultures were prepared as described in Example 1. 3M Clean-Trace surface ATP system swabs were replaced with sterile rayon-tipped applicators, as described in Example 1. The bacterial suspensions were diluted to approximately 107 CFU/ml in Butterfield's buffer. One hundred-microliter aliquots of the suspension were added directly to the swabs. BARDAC 205M hydrogel beads were prepared as described in Preparative Example 5. Up to three hydrogel beads (i.e., 0 bead, 1 bead, or 3 beads) were added to individual test units and each applicator was inserted into a Clean-Trace surface ATP test unit to activate ATP detection according to the manufacturer's instructions. The test unit was immediately inserted into the reading chamber of a NG Luminometer, UNG2 and RLU measurements were recorded at 20 sec intervals using the “Unplanned Testing” mode of the luminometer until the number of RLUs reached a plateau. The results are shown in Table 5. The data indicate that the BARDAC 205M beads, 205M-1p, permeabilized the bacteria, causing release of ATP from cells. The relative light units (RLU) increased over time in the samples containing the BARDAC beads, with a larger increase observed in a short period of time with higher number of beads. In contrast, the samples without the beads did not show a similar increase in RLU.
S. aureus
E. coli
S. aureus and E. coli overnight cultures were prepared as described in Example 1. Immediately before use in these tests, the bacterial suspensions were diluted in Butterfield's buffer to concentrations of approximately 106 and 107 CFU per milliliter. Luciferase/luciferin reagent (300 μl) from Clean-Trace surface ATP system was removed and added to 1.5 ml microfuge tubes. Ten-microliter amounts of the bacterial suspensions were added directly to individual microfuge tubes containing the reagents. BARDAC 205M hydrogel beads were prepared as described in Preparative Example 5. Up to three hydrogel beads (i.e., 0 beads, 1 bead, 2 beads or 3 beads) were added to each tube. Relative Light Units (RLUs) were recorded at 10 sec interval in a bench top luminometer (FB-12 single tube luminometer with software), as described in Example 2. The results of the experiments are shown in Table 6. The results indicate that the BARDAC 205M beads, 205M-1p, were able to lyse bacteria and release ATP from cells. The relative light units (RLU) increased over time in tubes containing at least one BARDAC 205M bead, with a larger increase observed in a short period of time with higher number of beads. Tubes containing no beads did not show a significant increase in RLU's.
S. aureus
E. coli
S. aureus and E. coli overnight cultures were prepared as described in Example 1. One milliliter of the overnight culture in tryptic soy broth (approximately 109 CFU/ml) was boiled for 10 min to lyse the cells. Both the live and the dead cell suspensions were diluted to approximately 107 and 108 CFU/mL in Butterfield's buffer. 3M Clean-Trace surface ATP system swabs were replaced with sterile rayon-tipped applicators, as described in Example 1. Ten microliter amounts of live, dead, or mixtures of both live and dead bacterial suspensions were added directly to the rayon applicators or Clean-Trace surface ATP swabs. A BARDAC 205M hydrogel bead, 205M-1p, was added to the test units and each applicator or swab was inserted into a Clean-Trace surface ATP test unit to activate ATP detection according to the manufacturer's instructions. The test unit was inserted into a NG Luminometer, UNG2 instrument and RLU measurements were recorded at 15 sec intervals using the “Unplanned Testing” mode of the luminometer until the number of RLUs reached a plateau. The results are shown in Table 7. The RLU observed in samples containing dead cells reached maximum within about 30 sec and the addition of BARDAC beads did not result in a significant change in measurable RLUs. In samples containing both live and dead cells, the addition of BARDAC beads caused the RLU to increase relatively slowly over a period of several minutes, indicating that the beads caused the release of ATP from live cells. In contrast, tubes containing the Clean-Trace surface ATP swabs (which contain a cell extractant), showed an initial increase in RLU until a maximum was reached within about 30 seconds to 1 min.
S. aureus
E. coli
S. aureus and E. coli overnight cultures were prepared as described in Example 1. Immediately before use in these tests, the bacterial suspensions were diluted in Butterfield's buffer to concentrations of approximately 108 CFU per milliliter. Luciferase/luciferin reagent (300 μl) from Clean-Trace surface ATP system was removed and added to 1.5 ml microfuge tubes. 100 nM solution of ATP (Sigma-Aldrich) was prepared in sterile water. Ten-microliter of ATP solution was added to individual microfuge tubes containing the reagents. Ten-microliter of the bacterial suspensions was added to some tubes containing reagents and ATP. BARDAC 205M hydrogel beads were prepared as described in Preparative Example 5 and one bead, 205M-1p, was added to some tubes. Relative Light Units (RLUs) were recorded at 10 sec interval in a bench top luminometer (FB-12 single tube luminometer with software), as described in Example 2. The results of the experiments are shown in Table 8. The results indicate that the addition of bacteria to pure ATP containing solution gave increased signal in the presence of BARDAC 205M beads. The extractants from beads were able to release ATP from cells leading to increased ATP levels which contribute to increased signal over the pure ATP background. Tubes containing no beads and bacteria did not show a significant increase in RLU's over that of pure ATP alone.
S. aureus
S. aureus
S. aureus overnight cultures were prepared as described in Example 1. BARDAC 205M beads were prepared as described in Preparative Example 5. Fresh, unpasteurized milk was obtained from a farm in River Falls, Wis. The milk was diluted with Butterfield's buffer (100-fold and 1000-fold). One hundred microliters of the diluted milk was mixed with 100 μl of luciferase/luciferin reagent from the Clean-Trace surface ATP system in a 1.5 ml tube and initial (T0) luminescence measurements were recorded in a bench top luminometer (FB-12 single tube luminometer with software) as described in Example 2. After several measurements, one BARDAC 205M bead, 205M-1p, was added to milk and subsequent luminescence measurements were recorded at 10-second intervals. To other samples, S. aureus (approximately 105 cells in 10 μL Butterfield's buffer) was added and, after taking the initial luminescence measurements, one 205M-1p bead was added to the sample. Subsequent luminescence measurements were recorded at 10-second intervals. The results are shown in Table 9. The data indicate that BARDAC beads were able to lyse bacteria spiked into milk and release ATP from cells, resulting in higher luminescence readings. The samples without added bacteria did not show a similar increase in luminescence after the BARDAC beads were added.
CRFK feline kidney cells (CCL-94, ATCC) were grown Dulbecco's Modified Eagle's Medium (DMEM) with 8% serum under CO2 atmosphere at 37° C. to achieve 70% confluency. The medium was removed from the bottles and the cell monolayers were washed and were trypsinized (0.25% trypsin) for about 5 min. The detached cells were diluted with fresh medium and centrifuged at 3K for 5 min. The cells were further washed twice and resuspended in phosphate-buffered saline (PBS). The cells were diluted with PBS to get the desired cell concentration. One hundred microliters of cells were mixed with 100 μl of luciferase/luciferin reagent from Clean-Trace surface ATP system in a 1.5 ml tube. In one experiment, the tube was placed into a bench-top luminometer (FB-12 single tube luminometer with software), as described in Example 2, and initial luminescence measurements were recorded. After several initial measurements, one BARDAC 205M bead, 205M-1p, was added to the cell suspension and the luminescence was monitored at 10 sec intervals. In another experiment, S. aureus (approximately 105 or 106 cells in 10 μL of Butterfield's buffer) was added to the tube before the luminescence measurements were started. The results are shown in Table 10. The data indicate that BARDAC beads were able to cause the release of ATP from both mammalian cells and bacterial cells, resulting in an increased luminescence after the beads were added. In another experiment, the luminescence was monitored in a sample containing CRFK cells and a BARDAC bead. After 3 minutes, S. aureus cells were added to the same sample and luminescence was monitored for additional two minutes. The results, shown in Table 10, indicate that the amount of luminescence increased upon addition of S. aureus cells.
S.
S.
S.
S.
S.
aureus
aureus
aureus
aureus
aureus
Various food extracts (Spinach, Banana, and ground turkey) were prepared by adding 10 g to 100 ml of PBS in a stomacher bag and stomaching the food samples in a stomacher. 100 μl of spinach and banana extract and 100 μl diluted turkey extract (10-fold and 100-fold) were mixed with 100 μl of luciferase/luciferin reagent from Clean-Trace surface ATP system in a 1.5 ml microfuge tube and background readings were taken in a bench top luminometer (20/20n single tube luminometer, Turner Biosystems, Sunnyvale, Calif.). The initial (and all subsequent luminescence measurements) were obtained from the luminometer using 20/20n SIS software that was provided with the luminometer. The light signal was integrated for 1 second and the results are expressed in RLU/sec. After several readings, one BARDAC 205M bead, 205M-1p was added to the food extract and ATP release was monitored at 10 sec interval. The background levels were very high with banana and turkey extract and the levels increased upon addition of BARDAC bead. After 2 minutes, S. aureus cells (105) were added to the same samples containing food extract and BARDAC bead and ATP release was monitored for additional four minutes. The ATP level increased upon addition of S. aureus cells (Table 11).
Overnight cultures of S. aureus were prepared as described in Example 1. Cooling tower water samples were obtained from two local cooling towers. One hundred microliters of water from each cooling tower was mixed with 100 μL of luciferin/luciferase reagent from Clean-Trace surface ATP system in individual 1.5 ml microfuge tubes. Luminescence was measured in a bench top luminometer (20/20n single tube luminometer with software) as described in Example 9, at 10-second intervals. After several measurements, one BARDAC 205M bead, 205M-1p, was added to the water sample and additional luminescence measurements were recorded to determine whether ATP was released from indigenous cells in the water samples. To other samples of cooling water from the same water towers, approximately 105 CFU of S. aureus (suspended in 10 microliters of Butterfield's buffer) were added into individual 1.5 ml tubes containing the luciferin/luciferase reagent. The luminescence was measured in a bench top luminometer (20/20n single tube luminometer). After taking background (T0) readings, one BARDAC 205M bead, 205M-1p, was added to the sample and luminescence was recorded at 10 second intervals. The results are shown in Table 12. The data indicate that the BARDAC beads were able to lyse bacteria spiked into water and release ATP from cells, causing an increase in luminescence over time.
S. aureus
S. aureus
BARDAC 205M and 208M beads were produced as described in Preparative Example 5.1 g of BARDAC 205M beads, 205M-1p, were added to 100 ml of distilled water and the water-soluble antimicrobial components were allowed to diffuse out of the beads and into the bulk solvent for 45 min. The beads were removed and the antimicrobial solution (“bead extract”) was saved. The amount of quaternary ammonium chloride (QAC) released was estimated using LaMotte QAC Test Kit Model QT-DR (LaMotte Company, Chester town, Md.). The amount of QAC released at the end of 45 min was 240 ppm.
A lysis solution (0.07% w/v Chlorhexidine digluconate (CHG, Sigma Aldrich) and 0.16% w/v Triton-X 100, Sigma Aldrich) was prepared in distilled water. A S. aureus overnight culture was prepared as described in Example 1 and the cells were diluted in Butterfield's buffer. One hundred microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system was added to 1.5 ml microfuge tubes containing approximately 105 cells. The lysis solution (25 or 50 μl) or bead extract (25 or 50 μl) was added to one of the microfuge tubes and the resulting luminescence was monitored in a bench top luminometer (20/20n single tube luminometer with software) as described in Example 9. To another set of samples one BARDAC 205M or 208M bead was added and the luminescence was monitored similarly. The results are shown in Table 13. The data indicate that the luminescence generated by the release of ATP from the bacteria was very gradual in samples that received the BARDAC beads. In contrast, samples that received either the lysis solution or the bead extract showed a rapid increase in luminescence, corresponding to a rapid release of ATP from the bacteria.
Hydrogel beads with various amounts of BARDAC 205M or 208M were prepared as described in Preparative Example 5. S. aureus and E. coli overnight cultures were prepared as described in Example 1. One hundred microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system was added to individual 1.5 ml microfuge tubes containing approximately 105 CFU of one of the respective bacterial cultures. One bead or Clean-Trace surface ATP swab was added to each tube. Luminescence, resulting from the release of ATP from the cells, was recorded at 10 sec intervals in a bench top luminometer (20/20n single tube luminometer with software) as described in Example 9. The results are shown in Tables 14 and 15. The data indicate that ATP release was very gradual in the samples containing the beads. In contrast, samples containing the swabs (which contain a cell extractant solution) showed a very rapid release of ATP from the cells.
Hydrogel beads with various amounts of BARDAC 205M or 208M were prepared as described in Preparative Example 1. A S. aureus overnight culture was prepared as described in Example 1. Microfuge tubes (1.5 mL) were prepared by adding 100 microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system. 100 microliters of the diluted suspension were added directly to individual microfuge tubes (i.e., approximately 105 CFU per tube). Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (20/20n single tube luminometer with software), as described in Example 9, and an initial (T0) measurement of RLUs was recorded. A hydrogel bead containing extractants was added to individual tubes and RLU measurements were recorded at 10 sec intervals until the number of RLUs reached a plateau or began to decrease (Table 16). The data indicate that all four of the bead formulations caused the release of ATP from the microbial cells.
Hydrogel beads with various amounts of BARDAC 205M or 208M were prepared as described in Preparative Example 5. Cultures of S. aureus, P. aeruginosa and S. epidermidis were prepared as described in Example 1. Microfuge tubes (1.5 mL) were prepared by adding 100 microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system. 100 microliters of the diluted suspension were added directly to individual microfuge tubes (i.e., approximately 105 CFU per tube). Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (20/20n single tube luminometer with software), as described in Example 9, and an initial (T0) measurement of RLUs was recorded. A hydrogel bead containing extractants was added to individual tubes and RLU measurements were recorded at 10 sec intervals until the number of RLUs reached a plateau or began to decrease (Table 17). The data indicate that all of the bead formulations caused the release of ATP from the microbial cells.
S. aureus
P. aeruginosa
S. epidermidis
S. enterica subsp. enterica
Hydrogel bead with 50% solution of BARDAC 205M was prepared as described in Preparative Example 5. Cultures of a number of different microorganisms were prepared as described in Example 1. Microfuge tubes (1.5 mL) were prepared by adding 100 microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system. 100 microliters of the diluted suspension were added directly to individual microfuge tubes (i.e., approximately 105 or 106 or 107CFU per tube). Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (20/20n single tube luminometer with software), as described in Example 9, and an initial (T0) measurement of RLUs was recorded. A hydrogel bead made from 50% BARDAC 205M solution, 205M-2p, was added to individual tubes and RLU measurements were recorded at 10 sec intervals until the number of RLUs reached a plateau or began to decrease (Table 18). The data indicate that the hydrogel bead containing BARDAC 205M caused the release of ATP from a variety of microbial cells.
C.
C.
K.
E.
E.
E.
E.
C.
S.
S.
S.
M.
albicans
albicans
kristinae
faecium
faecium
faecalis
faecalis
xerosis
pneumoniae
aureus
aureus
luteus
Hydrogel bead with 50% solution of BARDAC 205M, 205M-2p, was prepared as described in Preparative Example 5. S. aureus and E. coli overnight cultures were prepared as described in Example 1. One hundred microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system was added to individual 1.5 ml microfuge tubes containing approximately 105 or 106 CFU of one of the respective bacterial cultures. Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (20/20n single tube luminometer with software), as described in Example 9, and an initial (T0) measurement of RLUs was recorded. One 205M-1p bead was added to each tube. One set of tubes were vortexed for 5 sec between each reading and luminescence resulting from the release of ATP from the cells, was recorded at 10 sec intervals. The other set of tubes were not vortexed, but allowed to sit for 5 sec between each readings. The results are shown in Table 19. The data indicate that ATP release was very rapid in tubes that were mixed and very gradual in the samples that were not mixed.
S. aureus
E. coli
S. aureus and E. coli overnight cultures were prepared as described in Example 1. One hundred microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system was added to individual 1.5 ml microfuge tubes containing approximately 105 or 106 CFU of one of the respective bacterial cultures. Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (20/20n single tube luminometer with software), as described in Example 9, and an initial (T0) measurement of RLUs was recorded. One BARDAC 205M bead, 205M-2p was added to each tube and in one set of tubes the beads were crushed using the blunt end of a sterile cotton swab. Luminescence, resulting from the release of ATP from the cells, was recorded at 10 sec intervals. The results are shown in Table 20. The data indicate that the crushed beads rapidly released ATP from cells unlike uncrushed beads which showed a gradual increase in ATP levels.
S. aureus
E. coli
Hydrogel beads with various amounts of chlorhexidine digluconate (CHG) or Cetyl trimethylammonium bromide (CTAB) and Triclosan were prepared as described in Preparative Example 5. S. aureus and E. coli overnight cultures were prepared as described in Example 1. One hundred microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system was added to individual 1.5 ml microfuge tubes containing approximately 106 CFU of one of the respective bacterial cultures. Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (20/20n single tube luminometer with software), as described in Example 9, and an initial (T0) measurement of RLUs was recorded. One bead containing the extractant was added to each tube. Luminescence, resulting from the release of ATP from the cells, was recorded at 10 sec intervals. The results are shown in Tables 21. The data indicate that CHG, CTAB and Triclosan beads were able to release ATP from cells.
S. aureus
E. coli
Hydrogel beads with cationic monomers were prepared as described in Preparative Example 2. S. aureus and E. coli overnight cultures were prepared as described in Example 1. One hundred microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system was added to individual 1.5 ml microfuge tubes containing approximately 106 CFU of one of the respective bacterial cultures. Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (20/20n single tube luminometer with software), as described in Example 9, and an initial (T0) measurement of RLUs was recorded. One bead containing the extractant was added to each tube. Luminescence, resulting from the release of ATP from the cells, was recorded at 10 sec intervals. The results are shown in Tables 22. The data indicate that beads containing cationic monomers were able to release ATP from cells.
S. aureus
E. coli
Hydrogel fibers were prepared as described in Preparative Example 6. S. aureus and E. coli overnight cultures were prepared as described in Example 1. One hundred microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system was added to individual 1.5 ml microfuge tubes containing approximately 105 or 106 CFU of one of the respective bacterial cultures. Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (20/20n single tube luminometer with software), as described in Example 9, and an initial (T0) measurement of RLUs was recorded. About 5 mg of hydrogel fiber containing the extractant was added to each tube. Luminescence, resulting from the release of ATP from the cells, was recorded at 10 sec intervals. The results are shown in Table 23. The data indicate that fibers containing microbial extractant were able to release ATP from cells.
S. aureus
E. coli
BARDAC 205M was diluted in water to achieve 0.1%, 0.5%, and 1% solution in water. S. aureus and E. coli overnight culture was prepared as described in Example 1 and the cells were diluted in Buttefield's buffer. One hundred microliters of luciferin/luciferase reagent from Clean-Trace surface ATP system was added to 1.5 ml microfuge tubes containing approximately 105 cells. Immediately after adding the bacterial suspension, the tube was placed into a bench-top luminometer (20/20n single tube luminometer with software), as described in Example 9, and an initial (T0) measurement of RLUs was recorded. One to 5 microliters of BARDAC 205M solution was added to each of the microfuge tubes and the resulting luminescence was monitored in a bench top luminometer (20/20n single tube luminometer). The results are shown in Table 24. The effective concentration of BARDAC 205M to achieve good signal was between 0.0025 to 0.005%.
Hydrogel beads containing luciferin were made either using direct method (Preparative Example 3) or by post-absorption (Preparative Example 7).
Microfuge tubes were set up containing 100 μl of PBS, 10 μl of 1 μM ATP and 1 μl of 6.8 μg/ml luciferase. Background reading was taken in a bench top luminometer (20/20n single tube luminometer with software), as described in Example 9, and hydrogel beads containing luciferin were added to the tube and reading was followed at 10 sec interval. The post-absorbed beads were more active than the preparative beads (Table 24).
Hydrogel beads containing luciferase were made either using direct method (Preparative Example 4) or by post-absorption (Preparative Example 8).
Microfuge tubes were set up containing 100 microliter of luciferase assay substrate buffer (Promega Corporation, Madison, Wis.) Background reading was taken in a bench top luminometer (20/20n single tube luminometer with software, as described in Example 9) and hydrogel beads containing luciferase were added to the tube and reading was followed at 10 sec interval. Both types of beads showed good activity (Table 26).
In a similar experiment, effect of increasing number of post-absorbed luciferase beads was tested. Microfuge tubes containing 100 microliter of luciferase assay substrate buffer (Promega) were set up and luciferase hydrogel beads (1-4 beads per tube) were added. The luminescence was monitored immediately in a bench top luminometer (FB-12 single tube luminometer with software as described in Example 2). The experiment was done in triplicates. The results, shown in Table 27, indicate a generally linear relationship between the number of beads per tube and the amount of luciferase activity.
S. aureus overnight culture was prepared as described in Example 1.
Immediately before use in these tests, the bacterial suspensions were diluted in Butterfield's buffer to concentrations of approximately 108 CFU per milliliter. Luciferase/luciferin reagent (600 μl) from Clean-Trace surface ATP system was removed and added to 1.5 ml microfuge tubes. Ten-microliter amounts of the bacterial suspensions were added directly to individual microfuge tubes containing the reagents. Size selected BARDAC 205M hydrogel beads were prepared as described in Preparative Example 9. Three hydrogel beads from each size-selected group were added to the tube and the test was done in five independent tubes for each of the beads. Luminescence was measured in a bench top luminometer (20/20n single tube luminometer with software, as described in Example 9) at 10-second intervals. The results of the experiments are shown in Table 28 and 29. The weights shown in the table indicate the total mass of the beads in each respective tube. The results indicate that all size-selected BARDAC 205M beads were able to lyse bacteria and release ATP from cells.
S. aureus and E. coli overnight culture were prepared as described in Example 1. Immediately before use in these tests, the bacterial suspensions were diluted in Butterfield's buffer to concentrations of approximately 108 CFU per milliliter. Luciferase/luciferin reagent (600 μl) from Clean-Trace surface ATP system was removed and added to 1.5 ml microfuge tubes. Ten-microliter amounts of the bacterial suspensions were added directly to individual microfuge tubes containing the reagents. Size selected BAC hydrogel beads were prepared as described in Preparative Example 9. Six hydrogel beads (BAC-1p) or eight hydrogel beads (BAC-2p, BAC-3p and BAC-4-p) from each size-selected group were added to the tube and the test was done in several independent tubes for each of the beads. Luminescence was measured in a bench top luminometer (20/20n single tube luminometer with software, as described in Example 9) at 10-second intervals. The results of the experiments are shown in Tables 30 to 32. The weights shown in the table indicate the total mass of the beads in each respective tube. The results indicate that BAC loaded beads were able to lyse bacteria and release ATP from cells. The size-selected beads (1.4 to 1.7 mm and 1.18 to 1.4 mm beads) containing BAC gave consistent increase in signal across the replicates.
E. coli 106 CFU
S. aureus 106 CFU
S. aureus overnight culture was prepared as described in Example 1. Immediately before use in these tests, the bacterial suspensions were diluted in Butterfield's buffer to concentrations of approximately 107 and 108 CFU per milliliter. Luciferase/luciferin reagent (600 μl) from Clean-Trace surface ATP system was removed and added to 1.5 ml microfuge tubes. Ten-microliter amounts of the bacterial suspensions were added directly to individual microfuge tubes containing the reagents. Size-selected BAC hydrogel beads were prepared as described in Preparative Example 9. Various amounts of hydrogel beads, BAC-3p, were added to the tube and the test was done in several replicates. Luminescence was measured in a bench top luminometer (20/20n single tube luminometer with software, as described in Example 9) at 10-second intervals. The results of the experiments are shown in Tables 33 and 34. The weights shown in the table indicate the total mass of the beads in each respective tube. The results indicate that BAC loaded beads were able to lyse bacteria and release ATP from cells. The size selected beads (1.18 to 1.4 mm beads) containing BAC gave consistent increase in signal across the replicates with different amount of beads.
The present invention has now been described with reference to several specific embodiments foreseen by the inventor for which enabling descriptions are available. Insubstantial modifications of the invention, including modifications not presently foreseen, may nonetheless constitute equivalents thereto. Thus, the scope of the present invention should not be limited by the details and structures described herein, but rather solely by the following claims, and equivalents thereto.
This application claims the benefit of U.S. Provisional Application Ser. Nos. 61/101,546 and 61/101,563, both filed Sep. 30, 2008.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2009/058538 | 9/28/2009 | WO | 00 | 7/7/2011 |
| Number | Date | Country | |
|---|---|---|---|
| 61101546 | Sep 2008 | US | |
| 61101563 | Sep 2008 | US |
