Patent Application
20240032543
Antimicrobial compositions are widely used for preventing the spread of infection. Antimicrobial compositions may be applied to or incorporated into surfaces that are frequently touched such as counter tops. In some cases, it may be desirable to functionalize materials with other compositions to give the materials antimicrobial properties. Textiles are popular materials for antimicrobial functionalization.
Antimicrobial textiles may be created by coating the textile with an antimicrobial agent. Such methods may produce a superficial antimicrobial surface which may not penetrate the fabric. In addition, the antimicrobial properties of the textile may not last through repeated laundry cycles. In some cases, chemical additives may be added to laundry wash cycles to give the textile qualities such as resistance to fouling or bacterial resistance. However, these additives may be released into the water stream at the end of the laundry cycle and may have a negative impact on the environment. In addition, it is often preferable that such antimicrobial functionalization does not change the appearance or quality of the textile and that it be durable during and after laundering, storage, and use. If the textile is in contact with skin, it is also preferable that it does not cause any irritation or adverse reaction.
In some cases, airborne microbes may be more difficult to manage than surface microbes. Airborne microbes are often controlled through air flow and air filtration mechanisms. For example, surgical suites and certain patient rooms may have double door systems and negative pressure to control air flow. Air filters may be used, and medical staff may wear masks over their noses and mouths as a physical barrier to filter microbes from being inhaled by the wearer or exhaled into the environment. Microbes become trapped in the masks as the air flows through them so that, hopefully, the medical staff do not become infected and do not pass infection to others. However, such masks have limitations. Depending upon their porosity, masks may still allow some microbes to pass through. In addition, the masks may become saturated as they collect airborne particles, reducing their usefulness and useful shelf life, resulting in the need for more frequent replacement. Furthermore, since the masks function by trapping airborne microbes, the masks themselves become a hazard that can spread infection. Some microbes such as COVID-19 remain stable for long periods of time, such that the masks themselves risk contaminating medical staff and other patients. As such, while these masks function as reducing the spread of infection, they still have limitations and there is a need for further improvement.
Therefore, while it is desirable to functionalize materials such as textiles to provide antimicrobial properties, improved methods of functionalization are needed to enable large scale production of such textiles, to improve their characteristics, to improve performance, to reduce the environmental impacts of the process, and to allow for broader use of antimicrobial functionalized materials in antimicrobial products to reduce the spread of infections, particularly in patient care settings.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as forming the various embodiments of the present disclosure, it is believed that the disclosure will be better understood from the following description taken in conjunction with the accompanying Figures, in which:
Various embodiments include antimicrobial textiles. In some embodiments, the antimicrobial textile may include a sheet substrate comprising a textile and metal oxide nanoparticles in which the nanoparticles are present as a nanocomposite on the surface of and within the sheet substrate such as within the fibers of the textile. The metal oxide included in various antimicrobial textiles may include zinc oxide, for example. The antimicrobial textile may be configured to be worn on a body of a user such as a piece of personal protective equipment like a multilayer face mask in which the antimicrobial textile forms at least one layer of the face mask. In some embodiments, the personal protective equipment may be closing clothing.
The antimicrobial textile may be used for, or included in, various applications. For example, in some embodiments, the antimicrobial textile may also include an adhesive layer, such as when the personal protective equipment comprises a bandage. In some embodiments, the antimicrobial textile may be included in a feminine hygiene product. The antimicrobial textile may be used as a furniture upholstery. In some embodiments, the antimicrobial textile may be a surface cleaning product. In some such embodiments, the surface cleaning product may be a mop, sponge, rag or towel, for example. The antimicrobial textile may also be an article of bedding.
Particular embodiments include antimicrobial face masks including a multilayer sheet portion configured to cover a nose and mouth of a user, one or more of the sheets comprising a metal oxide textile nanocomposite, and straps configured for attachment of the mask to a user's head. In some embodiments, the metal oxide may be zinc oxide.
Other embodiments include methods of making antimicrobial textiles. The method may include applying a metal salt solution to a textile to diffuse the metal salt into the textile, the textile comprising a surface and interior fibers and drying the textile with the applied metal salt solution to bind the metal salt to the surface of and the interior fibers of the textile by forming a nanocomposite of metal nanoparticles or nanostructures in situ. The step of drying the textile may include heating the sheet. The metal salt may include zinc oxide. The resulting antimicrobial textile may then be incorporated into a wearable article, such as an article of personal protective equipment like a face mask worn over the nose and mouth.
Various embodiments include antimicrobial nanocomposites such as nanocomposite films and method of making the same. The antimicrobial nanocomposites may be antibacterial, antiviral, antifungal, antimold, antimildew, and/or antiparasitic, for example, to kill and/or reduce bacteria, viruses, funguses, mold, mildew and/or parasites. Unless otherwise stated, the use of the term “antimicrobial nanocomposites” as used herein includes, but is not limited to, antimicrobials, antivirals, antifungals, antimolds, antimildews, and/or antiparasitics to kill and/or reduce bacteria, viruses, funguses, mold, mildew and/or parasites. In some embodiments, the antimicrobial nanocomposites may kill, inactivate, and/or reduce the presence of, and/or may reduce the transmission of SARS-CoV-2 (causal agent of COVID-19) or other infectious viruses and bacteria on the surface of or through personal protective equipment. The antimicrobial nanocomposites may be provided as sheet-like layers such as films including functionalized materials like textiles and polymers. Such materials may be used to provide antimicrobial qualities to face masks and other personal protective equipment as well as medical apparel and materials such as bandages. The antimicrobial nanoparticles may be applied to the material, such as through soaking in metal or non-metal ionic salts, and the soaked material may then be dried such as in a commercial dryer to form nanoparticles or nanostructures. In this way, the nanoparticle forms and becomes bound to the material, on the surface and within the material, to form a nanocomposite. This process may be referred to herein as crescoating or crescoating technology. This method may be used to create functionalized materials without the use of environmentally damaging chemicals and without the use of stabilizing or capping agents.
Various antimicrobial nanocomposites as described herein may be used in medical and other patient care, food manufacturing and preparation or close contact environments. The use in medical environments may help reduce the risk of hospital-acquired infection. For example, personal protective equipment that may include antimicrobial nanocomposites include face masks, scrubs, surgical caps, lab coats and shoe covers. Further medical products which may include antimicrobial nanocomposites include patient gowns, sheets, bandages and wound care dressings, and sanitary products. Food production and preparation may include food surfaces.
Other uses for the antimicrobial nanocomposites include bedding such as sheets and blankets. In particular, such bedding may be useful in medical settings such as hospitals and clinics as well as congregate care settings such as assisted living environments. The antimicrobial nanocomposites may be used in apparel outside of the medical setting, such as ordinary consumer apparel like footwear including socks, slipper and shoe lining, undergarments, shirts and pants, as well as industrial apparel such as restaurant or flight attendant uniforms and uniforms for factory workers such as food processing factory workers. The nanocomposites may further be used as upholstery covering furniture and other home good, particularly furniture in high traffic locations such as airports and other transportation hubs, schools, and hotels. In still other examples, the nanocomposites may be used in materials for cleaning surfaces such as rope or sponge heads of mops, sponges, rags and towels.
Various materials may be functionalized using the methods described herein. For example, in some embodiments the material may be porous. It may be a synthetic or a natural textile including synthetic, semi-synthetic, or natural woven or non-woven textiles, fibers, or microfibers. Examples of textiles which may be used include cotton, polyester, nylon, spandex, rayon, linen, cashmere, silk, and wool, acrylic, modacrylic, olefin, acetate, polypropylene, polyvinylchloride, lyocell, latex, aramid, as well as blends or combinations of one or more of these or other materials or fibers. As such, the textile may be natural, such as silk, wool, cotton, cellulosics, flax, jute or bamboo, may be synthetic, such as nylon, polyester, acrylic, spandex, rayon, or a polymer such polypropylene, polyurethane. In some embodiments, the textile may be a mineral such as a glass fiber. Alternatively, the textile may be a blend of different materials including those listed above.
In some embodiments, the material may be a film such as a plastic film, a rigid material such as a rigid plastic, a foam, or a semi-rigid material such as a semi-rigid plastic.
In some embodiments, the material may be a non-woven material such as a material made through a melt blowing process. For example, the material may be a melt-blown polymer such as polypropylene. Such materials may be functionalized with antimicrobial nanoparticles and used as a layer of a multilayer face mask, such as a three-layer face mask, to provide both antimicrobial and filtration effects. In some embodiments, other functionalized materials are used in the face mask as a nanocomposite layer, along with a melt-blown polymer layer as is typically used to trap particulates and which may or may not be functionalized as describe herein, and one or more additional layers such as an inner and/or outer liner. Unless specifically stated otherwise, the term “material” or “textile” as used herein refers generally to all of the materials described herein that may be functionalized, including but not limited to all of the materials stated in the foregoing paragraphs.
Various types of compositions may be used for functionalizing the material. Useful compositions include metals such as transition metals or post-transition metals, metalloids, non-metals, rare earth metals, and alkaline earth metals. The compositions may be in their ionic, elemental and/or nanostructure form, for example. Such nanostructures may be nanoparticles, nanofilms, or other forms.
In some embodiments, the composition is an inorganic nanoparticle made of copper, iodine, silver, tin, zinc, titanium, selenium, nickel, iron, cerium, zirconium, magnesium, manganese, or combinations of more than one of these or other nanoparticles or alloys thereof such as a metal oxide. Examples of metals and metal oxides which may be used in various embodiments include silver, copper oxide, titanium dioxide, and zinc oxide. The metal and metal oxides and other compositions may be used alone or in combination.
In embodiments in which the composition includes nanostructures such as nanoparticles, the nanoparticles may have a size in the nanoscale range, such as between approximately 1 nm and 1000 nm, or between approximately 100 nm and 700 nm, for example. In some embodiments, the nanoparticles may be one or more metal oxides such as titanium dioxide, iron oxide, zinc oxide, copper oxide and silicon dioxide. In other embodiments, the nanoparticles may be non-metals such as selenium.
In some embodiments, the nanoparticles may form a nanocomposite with a porous support material such as sheet-like material. The porous support material may be cotton, cellulose, viscose, silk, aramid, nylon, polypropylene, polystyrene, polyester, polyurethane, polyamide, polyethylene, polycarbonate, or a combination of two of more of these or other materials. The nanocomposite may be a two-phase material including a nanoparticle such as a metal or non-metal nanoparticle on the surface of and within the material such as the fibers throughout the textile or other porous support material.
In some embodiments, the nanocomposite sheet may be used as a product or as a component of a product. In other embodiments, the nanocomposite sheet may be used with an adhesive which may be used to adhere the nanocomposite sheet to a surface of another product or material, either during production of the product or later by a consumer. The nanocomposite sheets may be present as layers such as single, double, triple, or greater numbers of sheets. The nanocomposite sheets may be hydrophobic, hydrophilic, electrostatic, or combinations thereof.
An example of an adhesive nanocomposite sheet is shown in
In other embodiments, the nanocomposite sheet may form one or more layers of personal protective equipment such as face masks. An example of such an embodiment is shown in
The antimicrobial nanocomposite sheets in personal protective equipment may allow the microbes such as bacteria and/or viruses such as COVID-19 or other microbes to be killed and/or inactivated on contact. The antimicrobial nanocomposite sheets may be used in personal protective equipment with or without additional layers such as microbe filtration sheets, or they may additionally function as filtration sheets. By inactivating the microbes on contact, the antimicrobial nanocomposite sheets provide not only a different method of preventing the spread of microbes in the air which may be used as an alternative to or in addition to filtration, but they also reduce the contamination of the surfaces of the personal protective equipment and the risk of spread by touch. Furthermore, because the nanocomposites maintain their antimicrobial effect even after washing, such as after washing 10 times or more, personal protective equipment such as masks made from the antimicrobial nanocomposites have an extended lifespan as compared to traditional filtration materials.
In the example shown in the
In other examples, the antimicrobial nanocomposite sheets may be used as a component of a feminine hygiene product such as tampons or sanitary pads which absorb menstrual blood. In such embodiments, the antibacterial properties provided by the antibacterial nanocomposite may help to reduce the risk of infection in a user such as toxic shock syndrome due to an overgrowth of group Staphylococcus aureus or toxic shock like syndrome due to group Streptococcus bacteria. For example, the antibacterial nanocomposite may kill, inactivate, prevent, reduce, and/or inhibit the growth of such bacteria in the feminine hygiene product.
An example of a tampon according to various embodiments is shown in
An example of a sanitary pad according to various embodiments is shown in a cross-sectional view in
In still other examples, the antimicrobial nanocomposite sheet may be used in dressings for wounds in order to reduce the risk of infection. Such dressings may be used on general cuts and abrasions, for post-surgical incisions, or in the field for wounds incurred in an accident or during armed conflict, for example. The dressings which include the antimicrobial nanocomposite sheets may be absorbent pads such as gauze pads which may be applied to a wound and held with compression such as by a wrap or may be adhesive bandages, for example. In other embodiments, the antimicrobial nanocomposite sheet may be used in dressings or other materials for cleaning and caring for and maintaining stomas as needed with colostomy bags and dressings, feeding tubes, and ventilator tubes, where the nanocomposite material may reduce the risk of viral or bacterial contamination.
An example of an antimicrobial wound care pad is shown in
Various materials such as textile sheets or other sheets or porous materials may be used in the antibacterial nanocomposite sheets, and the antibacterial nanocomposite sheets may be created through a functionalization process. Alternatively, textile threads, fibers or filaments may be functionalized according to the processes described herein, and the functionalized threads, fibers or filaments may subsequently be woven or otherwise formed into textile sheets.
The functionalization process may begin with applying the antimicrobial composition such as the nanoparticle composition to the material to impregnate the material with the composition. The impregnation of the material with the metal salt can be done by immersion or by spraying, for example. In some embodiments the composition is in a suspension or a solution such as an aqueous suspension or solution. While the composition is aqueous in many embodiments, it may alternatively be non-aqueous, such as a dilute solution (such as less than 50% or less than 25%) of an organic solvent such as acetone, ethanol, or isopropanol. Applying the composition to the material may include saturating the support material with the composition, such as by soaking the material in the composition or spraying the composition onto the support material.
Once the composition is applied to the material, the composition may be bound to the material through drying and/or through the application of heat such as through the use of a dryer. The heat may cause evaporation of the solution to initiate thermal reduction and crystallization of the nanoparticles onto the surface of the fibers of the fabric. This may be performed in a large scale through the use of large dryers such as commercial dryers or industrial dryers. Such commercial or industrial dryers may be capable of drying large quantities of material, such as large quantities of textiles, and operating for longer periods, such as continuously throughout the day. For example, such commercial dryers may have larger drying cylinder sizes, higher airflow, and higher BTU ratings which may help to reduce drying time and increase drying efficiency. For example, commercial dryers may have a capacity of 7 cubic feet or greater, or 30 pounds or greater. Industrial dryers may have a capacity of 30 pounds or greater, 50 pounds or greater, or even more. In some embodiments, the dryer may apply heat to the material. In some embodiments, the dryer may blow heated air toward the material and/or move the material while drying such as on a conveyor or by tumbling within the dryer.
Examples of dryer systems which may be used in various embodiments are shown in
Another example of a dryer 70 is shown in
In still a further example, the dryer 80 shown in
The application of heat to the treated material binds the composition to the material. For example, when nanomaterials are used, they may be grown inside the support material fiber and may be held physical in place by the surrounding material. The use of energy such as heat may facilitate crystallization.
Following heat treatment, the composition may remain bound to the material for an extended period of time. For example, the composition may remain bound to the material during one or more subsequent uses and/or washes such as laundry cycles.
In some embodiments, the composition may be added to a textile material during a laundry process. For example, the composition may be added to textile while the textile is being washed, such as during the wash cycle of a laundry machine. The composition may be provided as an additive to the laundry washing detergent or may be separately added during the washing cycle. The additive may be an aqueous solution of a metal or non-metal salt, for example. When the wash cycle is complete, the textile may be dried in a laundry dryer according to the normal laundry process. In this way, the textile may be functionalized during routine laundry processes. This may be particularly useful for industrial purposes, such as hotels, hospitals, nursing homes, and other facilities, to provide antimicrobial qualities to materials such as bedding (sheets, blankets, pillowcases, pillows, mattress covers) and/or clothing such as scrubs worn by medical personnel or gowns or other clothing worn by patients
A nanocomposite textile was prepared by soaking a textile in a zinc salt solution. The textile was a blend of cotton, polyester, nylon and spandex. The textile was then dried in a commercial dryer at a temperature of around 65 degrees Celsius. After the drying was complete, the zinc oxide nanocomposite textile was washed and examined under scanning electron microscopy (SEM). For comparison,
The zinc oxide nanocomposite textile prepared as described above was tested for antimicrobial properties using American Association of Textile Chemists and Colorists (AATCC) Test Method 100-2004. The experiment was repeated in triplicate, using both treated and untreated textile. Two bacterial species were used for testing: Pseudomonas aeruginosa, a Gram-negative bacterium, and Staphylococcus aureus, a Gram-positive bacterium. In each case, the textile was inoculated with the bacteria in broth, while a control was treated in the same manner but with broth alone. The textiles were allowed to incubate for 24 hours. The microbial concentrations on the textile were then determined by elution of the textile in neutralizing broth, dilution, and plating on Petri dishes. The resulting bacteria growth on the Petri dishes is shown in
Polyester, aramid, wool, silk, and nylon/cotton were functionalized with ZnO nanoparticles. The textiles were functionalized by soaking in an aqueous solution of zinc salts including zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride at an ideal concentration range of 0.1 to 0.75M for 30 minutes followed by heating in a conventional oven at 100 degrees Celsius or a dryer at 60 degrees Celsius until dry. The resulting functionalized textiles had nanoparticle loading of 1-3% w/w. The nanocomposite functionalized textiles were then tested for antibacterial activity in triplicate according to AATCC Test Method 100-2004 using Pseudomonas aeruginosa (PA) (Gram negative) and Staphylococcus aureus (SA) (Gram positive) as described above in Example 1. The antimicrobial properties of the zinc nanocomposite textiles were tested before wash and after undergoing 1, 5, and 10 wash cycles.
Before-wash antibacterial test: According to the AATCC protocol, the samples were treated at 0 hours (immediate elution), and then left for 24 hours. The harvested bacteria were plated on petri dishes to calculate the reduction in bacterial growth. The results are reported in % reduction and calculated by Equation 1:
R=100(B−A)/B (Eq. 1),
where R is the % reduction, A and B are the number of bacteria obtained from the inoculated treated test specimen swatches in the jar recovered either after incubation over the desired contact period “A”, or immediately after inoculation at “0” contact time) “B”. The same formula was used for 24 hours elution.
For all experiments, Equation 2 was used to evaluate if the bacterial source is effective, meaning if the initial concentration of bacteria used was enough to perform antimicrobial testing. Equation 2:
E=Log(B)−Log(A) (Eq. 2),
where E is the effective concentration, A and B are the number of bacteria recovered from inoculated untreated control textile immediately after inoculation, and after 24-hour incubation, respectively. E must be greater than 1.5 to be deemed effective.
In all experiments, the value of Log(B)−Log(A) ranged from 3 to 5, which confirms the effective bacterial concentration. Images of some of the resulting petri dish plates for the antimicrobial tests are shown in
Table 1 shows the results of the antimicrobial tests for the percent reduction of bacteria at both 0 hours (immediate elution) and after 24 hours of incubation with ZnO nanocomposite textiles. The immediate elution data reveals a reduction between 55% and 75% for the different textiles, which is an unexpected positive result since the bacteria were only exposed to the textiles for a few seconds. The data shows some variable effect on Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA). For some samples, negative values were observed and indicate that there were more bacteria recovered than the control. This could be due to variable adsorption properties of the textiles or to improper preparation of the bacterial concentrations. For longer elution, Table 1 shows that the nanocomposite textiles killed 100% of the bacteria that were exposed to them for 24 hours.
The zinc nanocomposite textiles were washed 1, 5 and 10 times using AATTC approved washing and drying machines to assess the durability of the antimicrobial textiles. Antibacterial properties were then tested according to the same protocol and using the same formula described above. Table 2 summarizes the effects of wash cycles on the antimicrobial properties after immediate elution (0 hours). Table 2 shows the effect of wash cycles on bacterial reduction (%) of Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) after 0 hours of incubation with zinc nanocomposite textiles. The data shows that the nanocomposite textiles retained their excellent antimicrobial properties for at least 10 wash cycles, indicating the high stability of the nanocomposite textiles.
The experiment of Example 2 was repeated but with the initial salt concentration during synthesis of the nanocomposite textile increased to double the nanoparticle loading of the textile, specifically zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride at an ideal concentration range of 0.75 to 1.5M. The resulting textiles had a nanoparticle loading of 3-6% w/w. The results were compared to those of Example 2 to evaluate the effect of concentration of nanoparticles on the antimicrobial properties of textiles. Table 3, below, shows the before-wash test results for the textiles of this example in comparison to the before wash test results for the textiles of Example 2. Table 3 shows the effect of nanoparticles loading on antimicrobial properties for Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) after immediate elution (0-hour incubation). These results show that the textiles can exhibit 100% antimicrobial efficiency, even at immediate elution (0 hours contact time), by increasing the initial salt concentration during the synthesis process to obtain a final nanoparticle loading of 3-6% in the nanocomposite textile. This is a remarkable performance that can be extremely useful to rapidly inactivate bacteria or viruses within seconds of contact with the textiles, opening new avenues for applications in personal protective equipment (PPE) such as medical masks, gowns, scrubs, and lab coats.
As in Example2, the nanocomposite textiles of this experiment were washed for 1, 5, and 10 wash cycles to test the effect of washing on the antimicrobial properties of the nanocomposite textiles using the same pathogens. The results are shown below in table 4, in which the effect of wash cycles on percent bacterial reduction of Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) after 24 hours incubation with zinc nanocomposite textiles is shown for 1, 5 and 10 wash cycles. The results demonstrate that the antimicrobial properties were retained even after 10 wash cycles for most of the textiles. For 10 wash cycles, the nanocomposite textiles showed more than 90% bacterial reduction for Staphylococcus aureus. The antimicrobial activity decreased by 20% and 40% for wool and silk respectively for Pseudomonas aeruginosa. We previously observed a similar behavior on selenium/polyurethane nanocomposite. This could be explained by the fact that Gram-negative bacteria such as Pseudomonas aeruginosa are usually more resistant to antimicrobial agents because of their extra polysaccharide layer outside the cell wall. Thus, for some textiles, such as wool, silk and selenium/polyurethane, the nanocoating functionalization may be repeated, such as through the processes described herein, after the textile is washed several times such as 10 times or more. This may be appropriate for use against Gram-negative bacteria such as Pseudomonas aeruginosa.
Samples of the nanocomposite textiles produced as described herein were characterized by the University of Minnesota Characterization Facility.
Morphological analysis of the nanocomposite textiles was performed including analysis of the structural integrity of the fibers, the size, shape, and homogeneity of distribution of nanoparticles, and the interface between the nanoparticles and the fibers. Assessment of these characteristics was performed using scanning electron microscopy (SEM).
In
In
The chemical and crystalline structures of the nanoparticles were also evaluated. The crystalline phase of the nanoparticles has a significant influence on their functionality. Nanoparticles were recovered from the cotton/polyester textiles by grinding. The powder was analyzed using Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD). Zinc oxide, nano titanium (TiO2) and nanoceramics were analyzed for subsequent functionality testing.
The XRD results are shown in
The characterization of the ceramic nanoparticles on aramid and silk were conducted using SEM and EDS and these results are shown in
A nanocomposite textile was prepared by soaking a textile in an aqueous solution of zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride at an ideal concentration range of 0.1 to 0.75M. The textile was a cotton polyester blend NIKE sock. The textile was then dried in a commercial dryer at a temperature of around 60 degrees Celsius. The textile was submitted to 100 wash and dry cycles. The zinc oxide nanocomposite textile prepared as described above was tested for antimicrobial properties using AATCC Test Method 100-2004 before the wash and dry cycles, after 50 wash and dry cycles, and at the end of the 100 wash and dry cycles. Staphylococcus aureus, a Gram-positive bacterium, was used for testing. The textile was inoculated with the bacteria in broth, while a control was treated in the same manner but with broth alone. The textiles were allowed to incubate for 24 hours. The microbial concentrations on the textile were then determined by elution of the textile in neutralizing broth, dilution, and plating on Petri dishes. Untreated control socks were tested for comparison of the antimicrobial effect of the nanocomposite socks. The results are shown in the graph presented in
Textile samples prepared according to the invention described were tested to evaluate the virucidal efficacy of the textiles against a surrogate to SARS-CoV-2 [(transmissible gastroenteritis virus (TGEV)] as described in Gonzalez, Andrew, et al. “Durable Nanocomposite Face Masks with High Particulate Filtration and Rapid Inactivation of Coronaviruses.” (2021). DOI: 10.21203/rs.3.rs-821052/v1
Two types of textiles were used in this example, a nylon-cotton textile and a melt-blown polypropylene material of the type used in face masks. The textiles used in this example were prepared by soaking the textile in zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride at an ideal concentration range of 0.1 to 0.75M and drying in a commercial oven at 100 degrees Celsius to evaporate the water and initiate nucleation and growth of the zinc oxide nanoparticles. The resulting nanoparticles or nanostructures were randomly distributed within and on the surface of the material and varied in shape and size from 5-500 nm. The SEM images presented in
After drying, the face mask was thoroughly washed in a commercial washing/drying unit according to the standard AATCC LP1: Machine Wash protocol. In the tests, 60 treated samples were compared to 60 untreated control samples for each fabric.
The TGEV (transmissible gastroenteritis virus), an alpha coronavirus causing gastrointestinal infections in pigs, was used as a surrogate to SARS-CoV-2. The TGEV was propagated and titrated in ST (swine testicular) cells. The cells were grown in Eagle's MEM medium supplemented with antibiotics and fetal bovine serum.
Aliquots (1 mL) of the virus recovery medium (MEM medium with 4% FBS) were distributed in 27 round bottom 13 mL plastic centrifuge tubes (Falcon). The 27 virus recovery tubes were divided into 3 groups of 9 tubes each. Group 1 was marked as control, group 2 marked as treatment, and group 3 was marked as leached particles control (treated control). In each group, 3 tubes were assigned for virus recovery at 3 different time points (10 min, 30 min, and 60 min).
Two square Petri dishes were marked as control and treatment. Parafilm squares (2×2 cm2) were cut and 9 parafilm squares were placed in each Petri dish. 4-Aliquots (75 μL) of TGEV suspension (with initial titer=˜6.5 Log TCID50/mL) were placed on the center of each parafilm square. Nine untreated (control) and 9 treated nylon/cotton specimens were placed over the surface of each parafilm square in the control-marked and treatment-marked Petri dishes, respectively, where the virus droplets were sandwiched between the tested textile and the parafilm squares. The virus droplets were absorbed immediately by the textile specimens as they are hydrophilic.
After each contact time point (10 min, 30 min, and 60 min), a set of 3 samples (in triplicate) was withdrawn from the control and treatment Petri dishes and each sample set (tested specimen with the absorbed virus and the parafilm square) was transferred into its corresponding virus recovery tube of group 1 and 2. To recover the surviving viral particles, all virus recovery tubes were vortexed for 2 min immediately after transferring the sample set in each of them.
In virus recovery group 3, a treated textile specimen was transferred first in each tube and vortexed for 2 min before adding 75 μL aliquot of the virus directly into each tube (without direct contact with the fabric). This was done to know whether a fraction of viral particles was inactivated by contact with the textile active ingredients that were possibly leached in the virus recovery solution following the recovery of the virus from the fabric.
The titer of surviving virus recovered in the recovery medium was performed by the 50% tissue culture infective dose (TCID50) method. Serial 10-fold dilutions were prepared from the recovery medium of each sample. These dilutions were inoculated in 80% confluent monolayers of ST cells, prepared in 96-well microtiter plates using 3 wells per dilution (100 μL of each sample dilution/well).
The infected cells were incubated at 37° C. in a 5% CO2 -incubator for up to five days and examined daily under an inverted microscope for the appearance of cytopathic effects (CPE). The highest dilution of the virus, which produced CPE in 50% of the infected cells, was considered as the endpoint. The titer of the surviving virus in each sample was then calculated by the Karber method (Karber, G. (1931). 50% end point calculation. Archivfitr Everithentelle Pathologic and Pharmakologie, 162, 480-483) and expressed as log10 TCID50/sample.
The entire experiment was repeated one more time on a separate day. Both experiments used triplicate samples for each contact time and hence the results are shown as an average of 6 replicates.
To gain some insight on the mode of action on virus inactivation, we quantified the viral genome copy numbers in the elution buffer after virus recovery from the control and treated samples. Viral RNA was extracted from 140 μL of sample using QIAamp DSP Viral RNA Mini Kit (Qiagen, Germany) according to the manufacturer's instructions. The RNA was eluted in 100 μL of elution buffer and stored at −80° C. until used for viral genome quantification. For RT-qPCR, we used PCR primer set and probe shown in Table 5. The RT-qPCR primers were designed to target a conserved 146 bp region [corresponding to the region between nucleotides 370 and 515 of the TGEV S gene with reference to (with reference to the sequence of TGEV- GenBank accession no.: KX900410.1)]. The primers and probe were manufactured by Integrated DNA Technologies (IDT, Coralville, IA). The reactions were performed using AgPath-ID One-Step RT-PCR kit (Applied Biosystems by Thermo Fisher Scientific, Waltham, MA).
The reaction mixture (25 μL) consisted of 5 μL of template RNA, 12.5 μL of 2× RT-PCR buffer, 1 μL 25× RT-PCR Enzyme Mix, 0.50 μL of 10 μM forward primer (200 nM final concentration), 0.50 μL of 10 μM reverse primer solution (200 nM final concentration), 0.30 μL of 10 μM probe (120 nM final concentration), and 5.20 μL of nuclease-free water. The RT-qPCR was performed in the QuantStudio™ 5 PCR thermocycler system (Thermo Fisher Scientific, Applied Biosystems™, catalog number: A28140). Reverse transcription was performed at 45° C. for 10 min. Taq polymerase activation was done at 95° C. for 15 min followed by 45 amplification cycles using a 95° C./15 s denaturation step and an annealing/extension step at 58° C. for 45 s. Fluorescence was measured at the end of annealing step in each cycle. In each run of RT-qPCR, standard curve samples and no template control were used as positive and negative controls, respectively.
The TGEV standard/calibration curve was constructed for absolute quantification of viral genome copy number, in which we used serial ten-fold dilutions of a 557 bp RT-PCR purified amplicon of TGEV S gene (including the 146 bp target sequence of the RT-qPCR prime/probe set). The 557 bp TGEV S gene fragment was produced by RT-PCR reaction using an in-house developed primer set shown in Table 5. Results were expressed as cycle threshold (Ct) values. The Ct values and standard curve were used to calculate the absolute genome copy number of TGEV, expressed as genome copies/sample.
Table 5 below shows the oligonucleotides for TaqMan-based TGEV RT-qPCR used for each PCR reaction in this example. A + polarity indicates virus sense and a − polarity indicates anti-virus sense. The position is the corresponding nucleotide position of TGEV genome (GenBank accession no.: KX900410.1) as reference.
The results presented here are the geometric means of 6 replicates. One-way ANOVA was performed and the significance of differences between the means were performed by paired comparison using Tukey test at significance=0.05. Table 6 below is a summary of the surviving TGEV titers and number of TGEV genome copies recovered from Nylon/cotton textile specimens after 10, 30, and 60 min contact times.
The titer of infectious TGEV particles recovered from nylon-cotton textile specimen after 10, 30, and 60 min contact times are shown in the bar graph presented as
The number of log reduction in the infectious titer (each first bar) and viral genome copies (each second bar) after 10, 30, and 60 min contact times with Nylon-cotton textile specimens are shown in the bar graph presented as
A summary of the surviving TGEV titers and number of TGEV genome copies recovered from facemask textile specimens after 10, 30, and 60 min contact times are shown below in Table 7. TCID50 is the 50% Tissue Culture Infectivity Dose.
The titer of infectious TGEV particles recovered from face mask textile specimens after 10, 30, and 60 min contact times is shown in
The results show that both of the treated textiles (Nylon-cotton and face mask material) could neutralize more than 3 order of magnitude of the infectious TGEV (≥99.9%) within 10 min of contact in humid conditions in the presence of an organic load (in the form of FBS in virus suspension). The lower reduction in the number of TGEV genome copies indicates that the majority of the neutralized viral particles were inactivated by the impact of the textile active ingredients on the viral envelope and/or capsid proteins. The small fraction of viral genome that was reduced indicate that disintegration in the viral capsids occurred in approximately >90% of the viral particles during 10 min of contact with the treated textiles. The strong virucidal efficacy of the nanocomposite materials despite the presence of high protein organic load indicates that this efficacy will not be affected by the high protein content of human's sputum droplets in which viruses such as Covid-19 are shed.
Nanocomposite materials were created using polyester, silk and nylon/cotton textiles by immersing the textiles in a zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride at an ideal concentration range of 0.1 to 0.75M for 30 minutes followed by heating in a conventional oven at 100° C. until dry. The nanocomposite materials were then exposed to a fungal strain of Candida Albicans per AATCC 30 method. The level of Candida Albicans was measured immediately after exposure (time zero) and after 24 hours of exposure to both the nanocomposite textiles as well as equivalent untreated textiles. The results are shown below in Tables 8-10, which includes the minimum, maximum and mean values for each sample at time 0 and at 24 hours. In all of the untreated textiles, there was an increase in the amount of fungus after 24 hours. In all of the treated textiles, there was a significant immediate reduction in the amount of fungus at time zero, followed by a complete elimination of fungus at 24 hours.
In another example, nanocomposite materials were fabricated at an industrial textile mill in the United States. A polyester/cotton blend fabric material was submerged in a treatment bath filled with the ionic precursor solution, as well as other finishing agents. Specifically, a zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride at an ideal concentration range of 0.1 to 0.75M solution was used in combination with a solution containing a fabric softening agents, an optical brightener, and a soil release agent. The fabric was then passed through an industrial heating system and heated at 150° C. for approximately 3 minutes. The final fabric was then spooled up, and a sample was sent to Vartest Laboratories LLC for antiviral and antibacterial efficacy testing. Testing for antibacterial efficacy was conducted following the AATCC 100 protocol using Staphylococcus Aureus and Klebsiella Pneumoniae. The results are shown in the graph presented in
Efficacy testing was performed on the nanocomposite materials as received, and then after 50 washes following a standardized washing methodology, AATCC TM96 specification VIc. Results are displayed in Table 11 below, in which percent indicates percent bacterial reduction measured in colony forming units per milliliter relative to a control.
Staphylococcus Aureus
Klebsiella Pneumoniae
Human Coronavirus OC43
As used herein, the terms “substantially” or “generally” refer to the complete or near complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is “substantially” or “generally” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, the nearness of completion will be so as to have generally the same overall result as if absolute and total completion were obtained. The use of “substantially” or “generally” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result. For example, an element, combination, embodiment, or composition that is “substantially” free of or “generally” free of an element may still actually contain such element as long as there is no significant effect thereof.
In the foregoing description various embodiments of the invention have been presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments were chosen and described to provide illustrations of the principals of the invention and its practical application, and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth they are fairly, legally, and equitably entitled.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/062766 | 12/10/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63123814 | Dec 2020 | US |
