Patent Grant
8151996
The field of the invention is serum separation, and especially to serum separation using a polymerizable composition that forms a barrier between the separated phases.
Among other sample manipulations, blood separation is a routine process that is typically required in many analytic tests. Most commonly, separation is carried out in a centrifuge using a polymeric gel having a density (about 1.04) that is between the heavier cell-containing phase and the lighter serum-containing phase. Examples for separation devices that use intermediate density polymers are found in U.S. Pat. No. 3,647,070 where polymer spheres form the barrier layer, while U.S. Pat. No. 5,266,199 describes a tube-and-ball valve that controls separation of the serum from the cell-containing phase. However, such barriers are often either incomplete and tend to leak, or impracticable for various reasons.
Alternatively, relatively impervious silicone-containing barrier layers can be used in the serum separation as described in U.S. Pat. No. 3,780,935, and drug-impermeable separation polymers are described in EP 0 928 301 in which fluid polymers are used as a barrier layers. Similarly, U.S. Pat. No. 4,235,725 describes the use of polybutadiene plus filler material as a barrier forming material. Such barrier materials often provide at least some advantage, but typically fail to maintain the separation over a prolonged period. In still further known serum separation devices, high-density polymers can be employed for blood separation in which the density is adjusted to a desirable degree with a density reducing component as taught in EP 0 705 882. Such compositions are often highly compatible with blood, and often exhibit favorable viscosity. However, such barrier layers are often unstable over prolonged periods. Alternatively, the viscosity of the intermediate polymer may also be increased in the separator tube by photopolymerization before the tubes is used for collection and separation as described, for example, in U.S. Pat. No. 6,361,700 or U.S. Pat. No. 6,248,844. Once more, while such tubes often provide increased sample stability, the barrier layer is typically unstable over prolonged periods and will deteriorate upon freezing.
Still further known devices and methods are described in EP 0 520 185 using fatty acid amides admixed with a gel, and EP 0 744 026 in which a peripheral water swellable band is taught as a barrier forming means. U.S. Pat. No. 3,920,557 described use of beads coated with an adhesive to form a barrier layer between the serum and the cell containing phase, while U.S. Pat. No. 4,101,422 discloses copolyesters with specific molecular weight and viscosity as barrier-forming compositions. While such known compositions tend to maintain the separation over at least relatively short periods, the separation layers are often not sufficiently stable to allow reliable storage over several days or while frozen.
Therefore, while numerous compositions and methods for centrifugal serum separation are known in the art, all or almost all of them suffer from one or more disadvantages. Thus, there is still a need to provide improved composition and methods to improve serum separation devices.
The present invention is directed to devices and methods for serum separator tubes that include a curable composition with an intermediate density to thereby locate between the serum fraction and the cell-containing fraction after centrifugation. Once separation of the phases is achieved, the curable composition is then subjected to conditions effective to solidify, crosslink, or otherwise strengthen the barrier formed by the curable composition.
Therefore, in one aspect of the inventive subject matter, a serum separator tube comprises a curable composition that is formulated to have a density between an average density of a serum fraction of whole blood and a cell-containing fraction of whole blood, and that is formulated to be mixable with or flowable in whole blood. Most typically, the composition will comprise a plurality of reactive groups in an amount effective to form a crosslinked composition upon initiation of crosslinking, wherein the crosslinked composition is impermeable to the cell-containing fraction of whole blood.
The curable composition in some preferred aspects is flowable and optionally thixotropic and will most preferably comprise a polymer (e.g., polyisoprene, polyester, polyacrylate, and/or silicone oil). Such polymers will typically include a reactive group (e.g., as pendant or terminal group) to allow formation of the crosslinked composition using a photo-initiated radical reaction. The photoinitiated reaction may proceed directly without a photoinitiator, or may require a one or more photoinitiators. Irradiation is preferably performed with UV light. Alternatively, it is contemplated that the crosslinked composition may also be crosslinked in a reaction using a radical starter (e.g., chemically or thermally activated).
Consequently, in another aspect of the inventive subject matter, a method of separating whole blood into a serum fraction and a cell-containing fraction includes a step of providing a collection tube that contains a curable composition and mixing whole blood with the curable composition, wherein the curable composition has a density between an average density of the serum fraction and the cell-containing fraction. The sample is then spun at a centrifugal force sufficient to separate the serum fraction and the cell-containing fraction such that the curable composition forms a barrier layer between the serum fraction and the cell-containing fraction, and in yet another step, the curable composition is cured after centrifugation.
Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention.
The inventor has discovered that serum separation can be significantly improved using a polymeric barrier material that is cured after the material has settled in a position between the lighter serum and the heavier cell-containing phase. Most preferably, it is contemplated that the remaining components and methods of serum separation remain as currently practiced.
In one exemplary aspect of the inventive subject matter, as shown in
As the sample contacts the incompletely cured polymer (the curable composition), it is contemplated that the polymerization terminator is diluted to a concentration that allows the polymerization to be re-initiated. Prior to re-initiation, the whole blood sample is separated in the container by centrifugation as shown in
While it is generally preferred that the separator tubes include a polyester polymer, it should be noted that the exact nature of the polymeric material is not limiting to the inventive subject matter, and that numerous alternative polymers are also suitable. Indeed all known polymers suitable for blood separation are deemed appropriate for use herein, including silicon oil, polyamides, olefinic polymers, polyacrylates polyesters and copolymers thereof, polysilanes, and polyisoprenes. To achieve a desired initial density (typically between about 1.03 and 1.05), it is contemplated that the density may be adjusted by virtue of molecular composition, as well as by inclusion of appropriate filler material (e.g., silica, latex, or other inert material). For example, suitable polymeric materials are described in U.S. Pat. Nos. 3,647,070, 3,920,557, or 3,780, 935, or in EP 0 928 301 or 0 705 882, which are incorporated by reference herein. Furthermore, it is contemplated that the serum separators may include additional materials and/or reagents to achieve a desired purpose. For example, the separators presented herein may include EDTA, heparin, citrate, dextrose, etc. It should be noted that the term “serum” is used herein to also include plasma, and other substantially cell free fluids derived from whole blood.
Depending on the particular material, it is contemplated that the mode and/or mechanism of polymerization to the separator polymer may vary considerably, and all know manners of polymerization are deemed suitable for use herein. For example, contemplated polymerizations include various radical or cationic polymerizations (e.g., using photolabile compounds, radical startes, etc.), condensation polymerizations, esterifications, amide formation, etc. Thus, reactive groups will especially include acid groups (and most preferably mono- and dicarboxylic groups), conjugated diene groups, aromatic vinyl groups, and alkyl(meth)acrylate. Such exemplary reactive groups and reaction conditions are described, for example, in U.S. Pat. No. 6,989,226, which is incorporated by reference herein. It should furthermore be appreciated that the reactive groups can be coupled to the terminus of a polymer as end groups as described in WO 99/64931, which is incorporated by reference herein, or that the reactive groups may be provided as pendant groups (e.g., as described in U.S. Pat. No. 5,336,736, incorporated by reference herein).
It is generally preferred that polymerization is fully supported by reactive groups on polymer, but additional reagents may also be suitable, including radical starters, including those described in U.S. Pat. Nos. 5,582,954, 4,894,315, and 4,460,675, which are incorporated by reference herein. Additionally contemplated compositions also include those that provide a crosslinking group to the polymer such that the polymer has reactive groups that react with a bifunctional crosslinker (e.g., ethylenically unsaturated compounds) to thereby form crosslinked polymers.
Thus, in another aspect of the inventive subject matter, a first polymerization may be performed to form the barrier material, and a second polymerization reaction or curing reaction employs a reaction that involves one or more reactive groups in the barrier polymer to harden/solidify the barrier. For example, where the barrier polymer is a polyester, curing of the polymer may be performed using a radical polymerization reaction that includes peroxo-, photolabile, or redox starters to generate a radical species that initiates the curing reaction between reactive groups (ethylenically unsaturated groups, epoxy groups, etc.) of polymeric strands of the polyester. Alternatively, catalyzed CLICK chemistry or other reactions may be employed so long as such reactions do not interfere with a downstream analytic process, and/or so long as the barrier polymer is curable to a degree that allows decanting and/or freezing without loss of separation.
In other aspects of the inventive subject matter, the polymerization reaction to form the barrier polymer may be incomplete (e.g., by addition of polymerization terminator, or depletion of reactive substrate) and the so formed barrier material can be cured after the barrier has formed by re-initiation of proper reaction condition. For example, where the concentration of the polymerization terminator has fallen below an inhibitory level via dilution with blood, polymerization may be started by UV irradiation. Alternatively, and depending on the particular curing mechanism, addition of reactive materials and/or crosslinkers may also be suitable. Further polymers and reactive groups suitable for photopolymerization are described in U.S. Pat. No. 5,086,138, which is incorporated by reference herein.
Thus, specific embodiments and applications of curable serum separator barrier materials have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
This application is a continuation of U.S. patent application having Ser. No. 12/691,670 filed on Jan. 21, 2010, issued on Aug. 24, 2010, as U.S. Pat. No. 7,780,861, which is a continuation of U.S. patent application having Ser. No. 11/499,436 filed on Aug. 4, 2006, issued on Mar. 9, 2010 as U.S. Pat. No. 7,674,388, which claims the benefit of priority to U.S. provisional application Ser. No. 60/707,299 filed on Aug. 10, 2005.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3647070 | Adler | Mar 1972 | A |
| 3780935 | Lukacs et al. | Dec 1973 | A |
| 3920549 | Gigiello et al. | Nov 1975 | A |
| 3920557 | Ayres | Nov 1975 | A |
| 3976579 | Bennett | Aug 1976 | A |
| 4050451 | Columbus | Sep 1977 | A |
| 4052320 | Jakubowicz | Oct 1977 | A |
| 4101422 | Lamont et al. | Jul 1978 | A |
| 4190535 | Luderer et al. | Feb 1980 | A |
| 4235725 | Semersky | Nov 1980 | A |
| 4295974 | Cornell | Oct 1981 | A |
| 4350593 | Kessler | Sep 1982 | A |
| 4386003 | Fiehler | May 1983 | A |
| 4417981 | Nugent | Nov 1983 | A |
| 4457782 | Honda et al. | Jul 1984 | A |
| 4569764 | Satchell | Feb 1986 | A |
| 4751001 | Saunders | Jun 1988 | A |
| 4770779 | Ichikawa et al. | Sep 1988 | A |
| 4816168 | Carrol et al. | Mar 1989 | A |
| 4844818 | Smith | Jul 1989 | A |
| 4867887 | Smith | Sep 1989 | A |
| 4946601 | Fiehler | Aug 1990 | A |
| 4994393 | Pradhan et al. | Feb 1991 | A |
| 5124434 | O'Brien | Jun 1992 | A |
| 5266199 | Tsukagoshi et al. | Nov 1993 | A |
| 5304605 | Murakami et al. | Apr 1994 | A |
| 5354838 | Murakami et al. | Oct 1994 | A |
| 5454958 | Fiehler | Oct 1995 | A |
| 5489386 | Saunders | Feb 1996 | A |
| 5494590 | Smith et al. | Feb 1996 | A |
| 5505853 | Satake | Apr 1996 | A |
| 5506333 | O'Brien et al. | Apr 1996 | A |
| 5510237 | Isogawa et al. | Apr 1996 | A |
| 5525227 | Vogler et al. | Jun 1996 | A |
| 5527843 | Murakmi et al. | Jun 1996 | A |
| 5663285 | Rounds | Sep 1997 | A |
| 5731391 | O'Brien et al. | Mar 1998 | A |
| 5776357 | Okamoto et al. | Jul 1998 | A |
| 5814220 | Mikami et al. | Sep 1998 | A |
| 5863704 | Sakurai et al. | Jan 1999 | A |
| 5888824 | Isogawa et al. | Mar 1999 | A |
| 5906744 | Carroll et al. | May 1999 | A |
| 5986039 | O'Brien et al. | Nov 1999 | A |
| 6072022 | O'Brien et al. | Jun 2000 | A |
| 6238578 | Fiehler | May 2001 | B1 |
| 6248844 | Gates et al. | Jun 2001 | B1 |
| 6280622 | Goodrich et al. | Aug 2001 | B1 |
| 6361700 | Gates et al. | Mar 2002 | B2 |
| 6979307 | Beretta et al. | Dec 2005 | B2 |
| 7090970 | Anraku et al. | Aug 2006 | B2 |
| 20060212020 | Rainen et al. | Sep 2006 | A1 |
| 20090146099 | Anraku et al. | Jun 2009 | A1 |
| Number | Date | Country |
|---|---|---|
| 0375566 | Jun 1990 | EP |
| 0766973 | Apr 1997 | EP |
| WO2005011495 | Feb 2005 | WO |
| WO2007139018 | Dec 2007 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20100314335 A1 | Dec 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60707299 | Aug 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12691670 | Jan 2010 | US |
| Child | 12861401 | US | |
| Parent | 11499436 | Aug 2006 | US |
| Child | 12691670 | US |
