KR20220164554A - antipathogenic face mask - Google Patents

Abstract

Disclosed herein are antiviral face masks and methods of their use to inactivate viruses that come into contact with the face mask. The face mask may include a fibrous material impregnated therein with silicon nitride powder and a layer surrounding the fibrous material. In some embodiments, silicon nitride is present in the fibrous material in a concentration of about 1 wt.% to about 15 wt.%.

Description

antipathogenic face mask

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority to US Provisional Application No. 63/009,842, filed on April 14, 2020, the contents of which are incorporated herein by reference in their entirety.

Field

The present disclosure relates to antiviral, antibacterial, and antifungal compositions, systems, methods, and devices. More specifically, the present disclosure relates to silicon nitride compositions, devices, and coatings for the inactivation and lysis of viruses, bacteria, and fungi.

The need for safe and reliable inactivation, removal, or lysis of viruses, bacteria, and fungi is universal. There is a widespread need to control pathogens that affect human health. Not only are materials with antipathogenic properties for human pharmaceutical therapies required, but also antipathogenic surface coatings and/or composites for various medical devices or equipment, examination tables, garments, filters, masks, gloves, catheters, endoscopic instruments, etc. Do.

Masks and respirators are typically limited to single use because the ability of pathogens trapped in filters to survive on surfaces for hours to days can lead to cross-infection, new aerosol release, and contaminated waste. Airborne particles are considered to be a major transmission route for pathogens such as influenza and SARS-CoV-2. Face coverings are critical to source control, but most masks produced today are simple filtering devices. Viral particles caught in masks can contaminate the wearer during daily use, but can also be re-aerosolized during mask adjustment or removal; Dirty masks represent a significant biohazard for disposal. This is unfortunate because viral viability on surgical masks and respirators is clinically preventable. For example, copper has been used for centuries in common hospital and household utensils due to its antibacterial properties. It has been incorporated into surgical masks but is toxic at concentrations that exceed nutrient levels. Several other antiviral agents have also been suggested for use in masks or respirators. These include silver, zinc, iodine, chitosan, peptides, quaternary ammonium salts, and nanoparticles. The effectiveness of most of these compounds has not yet been clinically demonstrated, and their value is debatable, as they may be toxins, allergens, irritants, or have limited bacterial or virucidal efficacy, or may be expensive. remains.

Accordingly, there is a need for safe and reliable methods for inactivating and killing viruses, bacteria, and fungi that can be applied to masks, medical devices, equipment, clothing, or other systems that may be in prolonged contact with the human body.

Provided herein are embodiments of antiviral face masks for inactivating and/or preventing the spread of viruses. In one aspect, a face mask can include a face mask body comprising a fibrous material having silicon nitride powder impregnated therewith. In some implementations, the face mask body can include an outer layer surrounding the fibrous material. In some embodiments, silicon nitride may be present in the fibrous material at a concentration of about 1 wt.% to about 15 wt.% and the silicon nitride inactivates viruses that come into contact with the fibrous material of the antiviral face mask. In some aspects, the silicon nitride in the fibrous material is present in a concentration of less than about 10 wt.%.

The face mask body may be made of a fibrous material such that the silicon nitride powder inactivates virus-containing droplets or aerosols as they are captured by the face mask fibers. The virus can be in contact with the silicon nitride powder for at least 1 minute.

Also provided herein is an embodiment for an antiviral face mask comprising a face mask body and one or more filters in the face mask body, each filter comprising at least one layer having silicon nitride powder impregnated therein. The silicon nitride may be present in a concentration of about 1 wt.% to about 15 wt.% and the silicon nitride inactivates viruses that come into contact with one or more filters of the antiviral face mask. In some aspects, the silicon nitride in each filter is present at a concentration of less than about 10 wt.%.

The face mask body and/or one or more filters are made of a fibrous material such that the silicon nitride powder inactivates virus-containing droplets or aerosols as they are captured by the one or more filters. The virus can be in contact with the silicon nitride powder for at least 1 minute.

Also described herein are methods for preventing the spread of viruses. The method may include contacting an antiviral face mask with a virus, wherein the silicon nitride powder is impregnated into the fibrous material of the face mask at a concentration of about 1 wt.% to about 15 wt.%. In some aspects, the silicon nitride in the fibrous material is present in a concentration of less than about 10 wt.%. Silicon nitride inactivates viruses.

In some aspects, the face mask and/or filter is made of a fibrous material such that virus-containing droplets or aerosols are captured by the mask or filter fibers and the silicon nitride powder inactivates them. The virus can be in contact with the silicon nitride powder for at least 1 minute.

Other aspects and iterations of the present invention are described more thoroughly below.

1 is an illustration of an influenza A virus.
2A is an illustration of viruses exposed to 0 wt.%, 7.5 wt.%, 15 wt.%, and 30 wt.% Si ₃ N ₄ for 10 minutes.
FIG. 2B is an illustration of the method used to determine viability of cells inoculated with virus exposed to Si ₃ N ₄ according to FIG. 2A .
3A is an illustration of viruses exposed to 15 wt.% Si ₃ N ₄ for 1, 5, 10, and 30 minutes.
FIG. 3B is an illustration of the method used to determine the viability of a virus after exposure to Si ₃ N ₄ according to FIG. 3A .
FIG. 4A is a graph of PFU/100 μl for influenza A exposed to 0 wt.%, 7.5 wt.%, 15 wt.%, and 30 wt.% Si ₃ N ₄ for 10 minutes according to FIG. 2A .
FIG. 4B is a graph of cell viability of cells inoculated with influenza A exposed to 7.5 wt.%, 15 wt.%, and 30 wt.% Si ₃ N ₄ for 10 minutes according to FIG. 2B .
5 contains photographs of cells inoculated with different ratios of virus to slurry exposed to various concentrations of Si ₃ N ₄ .
6A shows fluorescence microscopy images of MDCK cells before inoculation.
Figure 6b shows fluorescence microscopy images of MDCK cells after inoculation with the virus exposed to the control group.
6C shows fluorescence microscopy images of MDCK cells after inoculation with virus exposed to 30 wt.% Si ₃ N ₄ .
7A is a graph of PFU/100 μl for influenza A exposed to 15 wt.% Si ₃ N ₄ for 1 minute, 5 minutes, 10 minutes, or 30 minutes at room temperature.
7B is a graph of cell viability of cells inoculated with influenza A exposed to 15 wt.% Si ₃ N ₄ for 1 minute, 5 minutes, 10 minutes, or 30 minutes at room temperature.
8A is a graph of PFU/100 μl for influenza A exposed to 15 wt.% Si ₃ N ₄ for 1 minute, 5 minutes, 10 minutes, or 30 minutes at 4° C. FIG.
8B is a graph of cell viability of cells inoculated with influenza A exposed to 15 wt.% Si ₃ N ₄ at 4° C. for 1 minute, 5 minutes, 10 minutes, or 30 minutes.
9A shows a Raman spectrum of influenza A virus before inactivation.
9B shows Raman spectral changes of influenza A virus associated with chemical modification of RNA and hemagglutinin after inactivation after 1 minute of exposure.
10 shows that NH ₃ inactivates influenza A virus by the mechanism of alkali transesterification.
11 shows OPO stretching at the 5-coordinate phosphate group after inactivation.
12a shows the vibrational modes of methionine in the hemagglutinin structure.
12b shows the structural change of methionine in the presence of ammonia.
13 shows CS stretching homocysteine to methionine after inactivation.
14A is a graph of PFU/100 μl for feline calicivirus exposed to 15 wt.% or 30 wt.% Si ₃ N ₄ for 1 min, 10 min, or 30 min.
14B is a graph of cell viability of cells inoculated with feline calicivirus exposed to 30 wt.% Si ₃ N ₄ for 1 min, 10 min, 30 min, or 60 min.
15A shows H1H1 influenza A virus after inoculation into biogenic medium containing MDCK cells stained red after 10 minutes exposure to a slurry of 15 wt.% silicon nitride and stained green for the presence of filamentous actin (F-actin) protein. (nuclear protein, NP).
FIG. 15B shows the NP stained H1H1 influenza A virus of FIG. 15A .
Figure 15c shows the F-actin stained MDCK cells of Figure 15a .
16A shows H1H1 influenza A virus (nucleoprotein, NP) after inoculation into biogenic medium containing MDCK cells stained red without exposure to silicon nitride and stained green for the presence of filamentous actin (F-actin) protein. .
FIG. 16B shows the NP stained H1H1 influenza A virus of FIG. 16A .
Figure 16c shows the F-actin stained MDCK cells of Figure 16a .
17 shows the trimodal distribution of silicon nitride powder.
18 shows viability of MDCK cells as a function of β-Si ₃ N ₄ concentration (wt.%/mL).
19 shows a direct comparison of viral titers before and after exposure of influenza A to Si ₃ N ₄ powder for 30 minutes.
20 shows viability of MDCK cells as a function of α-Si ₃ N ₄ concentration (wt.%/mL).
21 shows a comparison of viral titers before and after exposure of influenza A to α-Si ₃ N ₄ powder for 30 minutes.
22 shows the trimodal particle size distribution of silicon nitride powder.
23 is an overview of antiviral testing methods.
24A shows Vero cell viability measured 24 hours after exposure to silicon nitride at concentrations of 5, 10, 15 or 20 wt.%/vol (n=4) incubated with cell culture medium for 1, 5, and 10 m. indicate
24B shows Vero cell viability measured 48 hours after exposure to silicon nitride at concentrations of 5, 10, 15, or 20 wt.%/vol (n=4) incubated with cell culture medium for 1, 5, and 10 m. indicate
25A is a graph of silicon nitride at concentrations of 5, 10, 15, and 20 wt.%/vol incubated with SARS-CoV-2 virus diluted in cell culture medium for 1, 5, and 10 m expressed as PFU/mL. represents the potency.
25B shows silicon nitride at concentrations of 5, 10, 15, and 20 wt.%/vol incubated with SARS-CoV-2 virus diluted in cell culture medium for 1, 5, and 10 m expressed as percent inhibition. represents the potency of
26a , 26B, 26C , and 26D are exemplary antiviral face masks.
27A , 27B , and 27C are exemplary antiviral face masks.
28A is a cross-section of an exemplary antiviral face mask body.
28B is a cross-section of an exemplary antiviral face mask body.
28C is a cross-section of an exemplary antiviral face mask body.
29 is an exemplary method for making a fabric in which silicon nitride particles are embedded.
30 is an exemplary system for making a fabric in which silicon nitride particles are embedded.

Various implementations of the present disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustrative purposes only. Those skilled in the art will recognize that other components and configurations may be used without departing from the spirit and scope of the present disclosure. Accordingly, the following description and drawings are illustrative and should not be construed as limiting. Numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, in certain instances, well known or common details are not set forth in order to avoid obscuring the description. A reference to an embodiment or implementation in this disclosure may be a reference to the same implementation or any implementation; Such reference refers to at least one of the embodiments.

Several definitions will now be presented that apply throughout this disclosure. Reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The appearances of the phrase “in one embodiment” in various places in this specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described that may be exhibited by some embodiments and may not be exhibited by others.

As used herein, the terms "comprising," "having," and "including" are used in an open, non-limiting sense. Singular terms are understood to encompass the singular as well as the plural. Accordingly, the term “mixtures thereof” also relates to “mixtures thereof”.

As used herein, “about” refers to a numerical value, whether explicitly indicated or not, including whole numbers, fractions, percentages, and the like. The term “about” generally refers to a range of numerical values that are to be considered equivalent to a recited value, e.g., having the same function or result, e.g., ± 0.5-1%, ± 1-5% of the recited value. or ± 5-10%.

As used herein, the term “appliance” includes compositions, devices, surface coatings, and/or composites. In some examples, the instruments may include various medical devices or equipment, examination tables, garments, filters, masks, gloves, catheters, endoscopic instruments, and the like. The utensils can be metal, polymeric, and/or ceramic (eg, silicon nitride and/or other ceramic materials).

As used herein, the term “silicon nitride” includes Si ₃ N ₄ , alpha- or beta-phase Si ₃ N ₄ , SiYAlON, SiYON, SiAlON, or combinations of these phases or materials.

As used herein, “inactivate” or “inactivation” refers to viral inactivation, which completely removes viruses or renders them non-infectious so that they cease to contaminate a product or subject.

As used herein, “personal protective equipment” or “PPE” means any device, article, or appliance worn or otherwise used by a person to minimize exposure to pathogens or other harmful substances. Non-limiting examples of PPE include body coverings, head coverings, shoe coverings, face masks, eye protection, face and eye protection, and gloves.

The terms used herein generally have their ordinary meaning in the art, within the context of this disclosure, and in the specific context in which each term is used. Alternate languages and synonyms may be used for any one or more of the terms discussed herein, and no special significance is attached to the terms, whether elaborated or discussed herein. In some cases, synonyms for certain terms are provided. A lengthy description of one or more synonyms does not preclude the use of other synonyms. The use of examples anywhere in this specification, including examples of any terms discussed herein, is illustrative only and is not intended to further limit the scope and meaning of the disclosure or any illustrative terms. Likewise, the disclosure does not limit the various implementations given herein.

Additional features and advantages of the disclosure will be presented in the description that follows, and will be apparent in part from the description, or may be learned by practice of the principles disclosed herein. The features and advantages of the disclosure may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present disclosure will be more fully apparent from the following description and appended claims, or may be learned by practicing the principles presented herein.

Provided herein are antipathogenic devices, compositions, and devices comprising silicon nitride (Si ₃ N ₄ ) for inactivation of viruses, bacteria, and fungi. Silicon nitride has a unique surface chemistry that is biocompatible and has 1) simultaneous osteogenic, osteoinductive, osteoconduction, and bacteriostatic activity, such as in spinal and dental implants; 2) killing of both Gram-positive and Gram-negative bacteria according to different mechanisms; 3) inactivation of human and animal viruses, bacteria, and fungi; and 4) Polymer- or metal-matrix composites, natural or man-made fibers, polymers, or metals containing silicon nitride that retain key silicon nitride bone reparative, bacteriostatic, antiviral, and antifungal properties. .

In embodiments, the antipathogenic composition may include silicon nitride. For example, the antipathogenic composition may include silicon nitride powder. In some embodiments, the antipathogenic composition may be a monolithic component comprising 100% silicon nitride. This component can be completely dense with no internal porosity, or it can be porous with a porosity ranging from about 1% to about 80%. The monolithic component may be used as a medical device or in devices where inactivation of viruses, bacteria, and/or fungi may be desirable. In another embodiment, an antipathogenic composition can be incorporated into a device or into a coating to inactivate viruses, bacteria, and fungi. In some embodiments, the antipathogenic composition may be a slurry comprising silicon nitride powder.

In some embodiments, the antipathogenic composition is capable of inactivating or reducing the spread of human viruses, bacteria, and/or fungi. Non-limiting examples of viruses that can be inactivated by the antipathogenic composition include influenza, enteroviruses, and coronaviruses (eg SARS-CoV-2, influenza A, H1N1, enterovirus, and feline calicivirus). include For example, silicon nitride bioceramics can be effective in inactivating influenza A viruses. In another example, silicon nitride powder may be effective in inactivating SARS-CoV-2. In some embodiments, silicon nitride coatings can reduce antibacterial and antiviral resistance and/or promote bone tissue repair.

Without being limited by theory, silicon nitride may provide a surface chemistry such that ammonia (NH ₃ ) is available for inactivating viruses, bacteria, or fungi. The surface chemistry of silicon nitride can be expressed as:

Si ₃ N ₄ + 6H ₂ O → 3SiO ₂ + 4NH ₃

SiO ₂ + 2H ₂ O → Si(OH) ₄

Nitrogen elutes faster (within minutes) than silicon because the surface silanols are relatively stable. In the case of viruses, it has surprisingly been found that silicon nitride can provide RNA cleavage via an alkaline transesterification reaction resulting in loss of genome integrity and viral inactivation. It can also reduce the activity of hemagglutinin.

In an embodiment, the antipathogenic composition comprises (i) slow but continuous elution of ammonia from the solid state rather than the usual gaseous state; (ii) no damage or negative effects on mammalian cells; and (iii) elution kinetics indicating an increasing intelligent elution with decreasing pH.

The device or appliance may include silicon nitride on at least a portion of the surface of the device for antiviral, antibacterial, or antifungal action. In embodiments, the device may include a silicon nitride coating on at least a portion of a surface of the device. The silicon nitride coating may be applied to the surface of the device as a powder. In some instances, the silicon nitride powder may be embedded or impregnated with at least a portion of the device. In some embodiments, the powder may have particles in the micron, submicron or nanometer size range. The average particle size may range from about 100 nm to about 5 μm, from about 300 nm to about 1.5 μm, or from about 0.6 μm to about 1.0 μm. In another embodiment, silicon nitride may be incorporated into the device. For example, the device may incorporate silicon nitride powder within the body of the device. In one implementation, the device may be made of silicon nitride.

The silicon nitride coating may be present on the surface of or in the device at a concentration of about 1 wt.% to about 100 wt.%. In various embodiments, the coating is about 1 wt.%, 2 wt.%, 5 wt.%, 7.5 wt.%, 8.3 wt.%, 10 wt.%, 15 wt.%, 16.7 wt.%, 20 wt.% .%, 25 wt.%, 30 wt.%, 33.3 wt.%, 35 wt.%, or 40 wt.% silicon nitride powder. In at least one example, the coating includes about 15 wt.% silicon nitride. In some embodiments, silicon nitride can be present in or on the surface of a device or appliance in a concentration of about 1 wt.% to about 100 wt.%. In various embodiments, the device or apparatus may contain about 1 wt.%, 2 wt.%, 5 wt.%, 7.5 wt.%, 8.3 wt.%, 10 wt.%, 15 wt.%, 16.7 wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 33.3 wt.%, 35 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 90 wt.%, to 100 wt.% silicon nitride.

In various embodiments, a device or appliance comprising silicon nitride for antipathogenic properties may be a medical device. Non-limiting examples of devices or instruments include orthopedic implants, spinal implants, pedicle screws, dental implants, indwelling catheters, endotracheal tubes, colonoscopy scopes, and other similar devices.

In some embodiments, silicon nitride is used in polymers, textiles, PPE, surgical gowns, plumbing, garments, air and water filters (e.g., domestic, industrial, or medical heating, ventilation, and air conditioning; filtration devices for anesthesia machines; ventilators; or CPAP machines), masks, tables, desks, instruments, handle handles, handles, toys, or toothbrushes, such as masks, hospital examination and operating tables.

In embodiments, silicon nitride can be incorporated into the PPE to inactivate or prevent the spread of viruses that come into contact with the PPE. In one implementation, the PPE is a mask and at least a portion of the mask is embedded with silicon nitride to form an antiviral face mask that traps and inactivates viruses that come in contact with the face mask. Without being limited by any one theory, antiviral face masks can "capture and kill" viruses that come into contact with silicon nitride within the face mask such that the virus is not only trapped within the face mask but is also inactivated. The inactivation mechanism of silicon nitride can act quickly to avoid cross-infection and the virus can be neutralized in a strain-non-specific manner.

Use of the term “antiviral face mask” or “face mask” herein includes a surgical face mask, a filtering face mask, a fabric washable mask, a breathing face mask, a cup-shaped respirator, a filtering facepiece respirator, an elastomeric half-facepiece respirator, an elastomer Full-face respirator, full-coverage face mask, half or full-face mask with cartridge, half-face or full-face mask with canister, powered air-purifying respirator, or worn over the wearer's face to protect the wearer from potential pathogens. It can refer to any mask operable to In at least one example, the face mask may be a surgical face mask. In another example, a face mask is a respirator. The antiviral face mask may include silicon nitride in at least a portion of the mask. In some instances, the antiviral face mask may be disposable and may be intended for single use. In another example, the antiviral face mask can be sterilizable and/or reusable to utilize replaceable filters.

26A - 26D are non-limiting examples of antiviral face masks that can include silicon nitride in at least a portion of the mask. Referring to FIG. 26A , in some implementations, the antiviral face mask 100 can be a surgical mask. In this implementation, the antiviral face mask 100 can include a face mask body 102 and one or more securing mechanisms 108 operable to secure the face mask body to the wearer. In some examples, face mask body 102 may include one or more pleats 103 to help conform the face mask to the wearer's face. 26B is an exemplary antiviral face mask 100 having a wrinkle-free face mask body 102 . In some implementations, face mask body 102 can include at least one layer with silicon nitride powder incorporated into or embedded within the layer.

In some embodiments, as seen in FIG. 26C , for example, the antiviral face mask 100 can be a cup-shaped respirator. In this implementation, the antiviral face mask 100 comprises a face mask body 102 , one or more securing mechanisms 108 , and a top of the face mask body 102 for adjusting the face mask 100 over the wearer's nose. The portion may include a deformable strip 104 . A deformable strip 104 may be attached near the top edge 105 of the face mask body 102 on the front face 106 . The deformable strip 104 can be made of a material that can be easily deformed by the wearer, including but not limited to plastic, spring steel wire embedded in plastic, or malleable aluminum. In additional embodiments, as seen in FIG. 26D , for example, face mask body 102 may further include one or more ports/valves 107 or one or more filters 109 to be incorporated into the mask. . In an example, filter 109 may include silicon nitride powder incorporated into or embedded in the filter. The silicon nitride can be in a layer or evenly distributed through the filter. In some examples, filter 109 may be disposable or replaceable.

In embodiments, the antiviral face mask 100 may include a disposable, replaceable filter 109 . In another implementation, the face mask 100 may include a pocket (not shown) for receiving a disposable filter having silicon nitride powder incorporated or embedded within the filter. In a further embodiment, the antiviral face mask ( 100 ) is washable with a deformable strip ( 104 ), one or more securing mechanisms ( 108 ) (eg adjustable straps), a breathing valve ( 107 ) and/or a chin guard. It can be made of fabric. Filters may be integral or insertable into each of these mask constructions.

27A - 27C show more examples of face masks that can include silicon nitride in a mask, a filter inserted into the mask, a cartridge attached to the mask, and/or a canister attached to the mask. 27A is an exemplary dual cartridge reusable half face mask that may include silicon nitride in the face mask body 102 and/or one or more cartridges 116 . 27B is an exemplary dual-cartridge reusable full-face mask that may include silicon nitride in the face mask body 102 and/or one or more cartridges 116 . 27C is an exemplary self-contained breathing apparatus that may include silicon nitride in the face mask body 102 , one or more cartridges 116 , and/or one or more canisters 118 .

Other non-limiting examples of masks include a particulate half mask which may include silicon nitride in the face mask body or filter, a dual cartridge disposable half mask which may include silicon nitride in the face mask body and/or one or more cartridges, a face mask A canister-type gas mask that may contain silicon nitride in the body and/or one or more canisters, a powered air-purifying respirator that may contain silicon nitride in the face mask body and/or one or more canisters, in the face mask body and/or one or more canisters. A continuous flow supply air respirator, which may include silicon nitride, and a full face mask having two inlet and exhalation valves operable to retain a filter or cartridge.

Referring again to FIGS. 26A - 27C , face mask 100 may be configured to be placed over the nose and mouth of a wearer and may include one or more securing mechanisms 108 for attaching the face mask to the wearer. Securing mechanism 108 may be one or more straps, loops, hooks, bands, or flaps for securing the face mask to the wearer's face. The securing mechanism 108 can be made of an elastic material or any fibrous material from which the mask body is made. In at least one example, face mask 100 can include two loops 108 , each operable to secure to the wearer's ears. In another example, face mask 100 can include two straps, each operable to be secured behind the wearer's head. In a further example, face mask 100 may include multiple straps or bands to be secured around the wearer's head. The outer layer 106 of the face mask body 102 may contact the wearer's face such that the fibrous material does not directly contact the wearer.

Face mask body 102 and/or filter 109 may include at least one layer, at least two layers, at least three layers, or at least four layers. In some implementations, one or more layers of the face mask body may be made of a fibrous material. The fibrous material may be a woven or non-woven material and may be breathable or non-breathable. In some examples, the fibrous material may be a spunbond nonwoven fabric. Non-limiting examples of fibrous materials include polypropylene, rayon, polyester, cellulose, non-oil-resistant materials such as KN95, N95, N97, N99, or N100 filters, oil-resistant materials such as P95, P97, P99, or P100 filters, and/or semi-oil-resistant materials such as R95, R97, R99, or R100 filters. Each layer of the face mask body may include the same or different fibrous materials. The fibrous material may have silicon nitride embedded therewith. In some embodiments, the fibrous material can be removable and/or disposable. For example, in some instances, the layer containing the fibrous material and/or filter may be removable from the rest of the mask body and discarded after one use.

28A - 28C are non-limiting examples of cross-sections of face mask body 102 and/or filter 109 . In one example, as seen in FIG. 28A , face mask body 102 can include fibrous material 111 and outer layer 112 . In this example, face mask body 102 can have outer layer 112 surrounding fibrous material 111 , wherein silicon nitride powder is incorporated into or into fibrous material 111 of face mask body 102 . impregnated The fibrous material 111 may be completely surrounded by the outer layer 112 such that the outer layer 112 essentially acts as a first layer and a third layer and the fibrous material 111 is between the first and third layers. It is the second layer embedded in the 28B is an exemplary cross-section of a face mask body 102 having three layers: silicon nitride fibrous material 111 , a first outer layer 113 , and a second outer layer 114 . In some examples, the first outer layer 113 and the second outer layer 114 can be made of the same material to function similarly to a single outer layer 112 as seen in FIG. 28A . In another example, the first outer layer 113 and the second outer layer 114 may be made of different materials. 28C shows a face mask body 102 having four layers: a fibrous material with silicon nitride ( 111 ), a second inner layer ( 115 ), a first outer layer ( 113 ), and a second outer layer ( 114 ). This is an exemplary section. In some examples, the first outer layer 113 and the second outer layer 114 can be made of the same material to function similarly to a single outer layer 112 as seen in FIG. 28A . In another example, the first outer layer 113 and the second outer layer 114 may be made of different materials. The fibrous material may include nonwoven fabrics such as spunbond fabrics. In some examples, the fibrous material ( 111 ), second inner layer ( 115 ), first outer layer ( 113 ), second outer layer ( 114 ), and/or outer layer ( 112 ) is polypropylene, polyester, rayon , nylon, acrylic fibers, N95 filters, zinc, copper, silver, iodine, citric acid, ammonium citrate, or other compounds having antiviral properties. In a further example, the second inner layer 115 , the first outer layer 113 , the second outer layer 114 , and/or the outer layer 112 may include silicon nitride.

In some examples, the face mask body may further include one or more ports or pockets for receiving one or more filters, canisters, or cartridges. In various implementations, where the face mask includes at least one filter, the filters can be stacked similar to the cross-sections of FIGS. 28A - 28C . In some examples, the filter may include silicon nitride within at least a portion of the filter. In another example, the filter may include a N95 filter or a carbon filter. In various instances, filters may be disposable and replaceable.

In some implementations, one or more layers of the face mask body and/or one or more filters may be coated with silicon nitride powder. In an example, a fibrous material or filter may be coated with silicon nitride. Standard coating methods known in the art may be used to coat the face mask body or filter.

In other embodiments, the silicon nitride is embedded into a layer, filter, canister, or cartridge of a face mask body using methods including, but not limited to, electrospinning, melt-spinning, melt-blown, weaving, or ultrasonic impregnation/embedding. may be incorporated, incorporated, or impregnated.

In an embodiment, silicon nitride may be embedded in a nonwoven fabric such as polypropylene using ultrasonic treatment. The resulting silicon nitride embedded fabric can be used to form any PPE. A multi-step process can be used to achieve the proper surface chemistry, adhesion, and activation of the Si ₃ N ₄ particles to the fabric. 29 is an exemplary manufacturing method 1000 and FIG. 30 is an exemplary manufacturing system 200 for embedding silicon nitride into nonwoven spunbond polypropylene fibers.

Based on packaging, transportation, or storage, nonwoven fabrics (ie, scrims) may require pre-cleaning. The purpose of the pretreatment step(s) is therefore to clean the fabric to improve its wetting properties and to add a coupling agent. First, fabric 202 is pretreated to improve cleanliness and wettability. In step 1002 , the fabric 202 is cleaned with hot deionized water in a first ultrasonic pretreatment tank 204 as a first pretreatment step. The structure of the tank 204 allows the fabric 202 scrim to continuously move under roller 216 tension through the pretreatment bath at a distance of about 8 to 10 cm above the tank bottom. An ultrasonic transducer 218 may be located on the outside bottom of the tank. In some examples, ultrasonic transducer 218 may operate at > 1000 W 25 kHz ultrasonic energy and up to 2000 W thermal energy. The pretreatment bath temperature may be set to 95°C ≤ T ≤ 100°C. The residence time of the fabric 202 in the bath may be up to about 5, 10, 15, or 20 minutes. For example, if the length of fabric 202 in pretreatment tank 204 is about 60 cm at any one point in time, the speed of fabric 202 through the bath may be 6 cm/min. The purpose of this first pretreatment tank 204 is to remove organic chemicals and loosely attached contaminants. The pretreatment tank 204 operates under a continuous circulation and filtration system to remove contaminants from the water. Upon exiting the pretreatment tank 204, a pressure wringer 220 wrings excess water out of the fabric 202 .

In step 1004 , the fabric is treated with a coupling agent in a second ultrasonic pretreatment tank 206 as a second pretreatment step. The second ultrasonic pretreatment tank may contain a water bath with an organic coupling agent. Coupling agents can facilitate bonding of the Si ₃ N ₄ particles to the fabric. Various examples of coupling agents include quaternary ammonium compounds (bromides), hydroxides, fluorides, or chlorides that may vary in carbon chain length but have the same or similar functional groups. In one embodiment, the coupling agent is n-dodecyl trimethyl ammonium bromide (DTAB). In another embodiment, the coupling agent can be dioctadecyl dimethyl ammonium bromide (DODA). The water bath may contain a coupling agent to water in a weight ratio of about 1:200 to about 1:1000. For example, a 1:200 ratio could be 1 gram of DTAB in 200 grams of water and a 1:1000 ratio could be 1 gram of DTAB in 1,000 grams of water (ie, 1 g per liter). An ultrasonic transducer 218 may be located on the outside bottom of the tank. In some examples, the second ultrasonic pre-treatment tank 206 can operate under the same conditions as the first pre-treatment tank 204 . As the coupling agent will adsorb onto the fabric during processing, replenishment of the solution will be necessary. This can be achieved as a separate larger mixing tank connected to the ultrasonic pretreatment tank 206 using a recirculating pumping system (not shown) via a metered addition system coupled with mechanical agitation within the ultrasonic pretreatment tank 206 itself. can Upon exiting the second ultrasonic pretreatment tank 206 , a pressure ringer 220 squeezes excess water from the fabric 202 and uses a heated blower (not shown) operating at about 100°C to remove the fabric 202 . Residual moisture can be removed from

In step 1006 , Si ₃ N ₄ particles are embedded in the fabric using sonication in an ultrasonic tank 208 with water, a dispersant, and Si ₃ N ₄ particles. In one embodiment, a fabric 202 scrim may be continuously fed to a third ultrasonic tank 208 containing an aqueous Si ₃ N ₄ dispersion. The Si ₃ N ₄ slurry dispersion may be prepared prior to passing the fabric 202 through the ultrasonic tank 208 . The composition of the slurry may include Si ₃ N ₄ powder, a dispersant, and deionized water. Dispersants can be ammonium salts of various organic compounds such as ammonium citrate. The selection and use of dispersants is routine to those skilled in the art. In an example, the dispersant may be Dolapix A88. In at least one example, the slurry may include 210 g Si ₃ N ₄ powder, 2.1 g Dolapix A88 dispersant, and 790 g deionized water. This composition corresponds to about 21 wt.% Si ₃ N ₄ powder. The slurry composition can be adjusted to achieve a desired concentration of Si ₃ N ₄ particles. Typically, the slurry composition may range from about 5 wt.% to about 40 wt.% Si ₃ N ₄ particles. The slurry is mixed separately using a high shear (propeller action) mixer while metering Si ₃ N ₄ powder, dispersant, and water (if necessary) into the ultrasonic tank 208 using a recirculating pumping system (not shown). Can be made in tanks. The embedding itself takes place within the ultrasonic tank 208 . Similar to the pretreatment, the ultrasonic transducer system 222 operates at ultrasonic energy of ≥ 1000 W 25 kHz and thermal energy of up to 2000 W, and at a temperature of 65 ° C ≤ T ≤ 75 ° C. The residence time of the fabric 202 within the ultrasonic tank 208 may be about 5, 10, 15, or 20 minutes. Using the previous example, if the length of fabric 202 in ultrasonic embedding tank 208 is about 60 cm at any one point in time, the speed of the fabric through the water bath may be about 6 cm/min. Upon exiting ultrasonic tank 208 , pressure ringer 220 squeezes excess slurry from fabric 202 .

In step 1008 , fabric 202 is then dried and the Si ₃ N ₄ particles are thermally bonded in drying and thermal bonding oven 210 . Thermal bonding oven 210 may be completely enclosed by inlet 209 and outlet 211 for fabric and heating element 219 . Thermal bonding is a series of smooth surface counter-rotating rollers that continuously feed fabric 202 into an oven to dry the fabric and then simultaneously apply heat and pressure to the fabric (i.e., calendaring as shown in FIG. 21 ). ( 217 ). Oven 210 can be operated at 90 °C ≤ T ≤ 100 °C and calendering roller 217 can be operated at 140 °C ≤ T ≤ 145 °C with an applied pressure of ≥ 500 psi (≥ 35 daN/cm). . Alternatively, the fabric can be passed directly through preheated calendering rollers without the need to enter a drying oven (not shown).

In step 1010 , fabric 202 is rinsed in ultrasonic rinse tank 212 with water and surfactant to remove excess silicon nitride particles not embedded in the fabric. In some embodiments, washing and rinsing can be performed in two separate steps. In one embodiment, they can be combined in one step. Previous thermal bonding operations can minimize the amount of unembedded particles. This step can be performed in a continuous ultrasonic bath similar to that used for the pretreatment and embedding steps. The ultrasonic rinse tank 212 may include a separate larger mixing tank with a pump and recirculation system (not shown) like other ultrasonic tanks. Within the recirculation system, a replaceable cartridge-type submicron filter may be utilized to retain particles released from the fabric. The rinse composition may include a surfactant and water. In some examples, the surfactant can be Triton X-100. An ultrasonic transducer 218 may be located on the outside bottom of the tank. Similar to the previous ultrasonic step, the rinse step ( 1010 ) is performed at approximately 5, 10, 15, or 20 minutes depending on the residence time of the fabric in the ultrasonic tank at a power level of ≥ 1000 W 25 kHz ultrasonic energy, up to 2000 W of heat. energy, and a temperature of 60 °C ≤ T ≤ 70 °C. After rinsing, fabric 202 may be passed through ringer 220 to remove excess water.

In step 1012 , rinsed fabric 202 is dried in drying oven 214 . The thermal bonding oven 214 may be completely enclosed by the inlet 213 and outlet 215 for the fabric and the heating element 219 . In some embodiments, the fabric 202 scrim may be fed to a continuous drying oven 214 operating at about 110° C. for a residence time of about 5, 10, 15, or 20 minutes. Fabric 202 may subsequently be wound onto take-up roll 203 .

The tanks and/or ovens associated with each step may be operatively connected such that a single roll of fabric 202 can be passed through each tank and/or oven throughout the process. Fabric 202 may be provided as a continuous roll. For example, fabric 202 may start at source roll 201 , unwind as it passes through various tanks and ovens, and end at take-up roll 203 . In at least one example, the fabric may be a nonwoven polypropylene spunbond fabric (ie scrim, -45 g/m ² ). Polypropylene is inherently hydrophobic (i.e. non-wetting). The fabric can be received as a continuous roll approximately 280 mm wide by ~1 kilometer long.

Silicon nitride incorporated in PPE, face mask bodies, filters, canisters, cartridges, etc. may be present in concentrations from about 1 wt.% to about 30 wt.%. In various examples, the fibrous material may comprise up to about 1 wt.%, up to about 2 wt.%, up to about 5 wt.%, up to about 7.5 wt.%, up to about 10 wt.%, up to about 15 wt.%, embedded in the fibrous material. wt.%, up to about 20 wt.%, up to about 25 wt.%, or up to about 30 wt.% silicon nitride powder. In at least one example, the silicon nitride in the fibrous material is present in a concentration of about 1 wt.% to about 15 wt.% throughout the fibrous material. In another example, the silicon nitride in the fibrous material is present in a concentration of less than about 10 wt.%. In various examples, the face mask or one or more filters of the face mask may contain at most about 1 wt.%, at most about 2 wt.%, at most about 5 wt.%, at most about 7.5 wt.%, at most about 10 wt.%, at most about 15 wt.%, up to about 20 wt.%, up to about 25 wt.%, or up to about 30 wt.% silicon nitride powder. In at least one example, the silicon nitride in the fibrous material is present at a concentration of about 1 wt.% to about 15 wt.% throughout at least a portion of the one or more filters of the face mask. In another example, the silicon nitride in the one or more filters is present at a concentration of less than about 10 wt.%. In some examples, the silicon nitride may be present in a canister or cartridge attached to the face mask at a concentration of about 1 wt.% to about 15 wt.% throughout at least a portion of the canister or cartridge. In another example, the silicon nitride in the canister or cartridge is present at a concentration of less than about 10 wt.%.

In some embodiments, the organic acid may further be incorporated into the fibrous material or layer of the mask. The acid may be selected from the group consisting of citric acid, malic acid, tartaric acid, succinic acid, oxalic acid, benzoic acid, isocitrate acid, acetic acid, lactic acid, ascorbic acid, (e.g., acids commonly found in fruits and vegetables, and combinations thereof. In an embodiment, the acid is complexly mixed with the silicon nitride powder and masked at a concentration in the range of 0.5 wt.% to 5.0 wt.%, preferably in the range of 1.5 to 3.0 wt.%, most preferably about 2.0 wt.% of the silicon nitride powder. can be buried in

CH₃CO₂ ^- + H₃O⁺. 이 반응은 국부 pH를 감소시켜 질화규소 입자의 인접지에서 산성화된 환경을 생성한다. 동시에, 다음과 같이 암모니아 및 암모늄을 방출하는 수분의 존재 하에 질화규소의 표면에서 화학 반응이 발생한다: Si₃N₄ + 16H₂O

3Si(OH)₄ + 4NH₄OH

4NH₃ + 4H₂O. 평형 상태에서 암모늄 및 암모니아의 농도는 pH에 따라 달라진다. pH가 증가함에 따라, 질화규소로부터 용리된 암모늄의 양은 감소한다. 용리된 암모니아의 상응하는 양이 증가하는 동안, 이의 농도는 암모늄의 농도보다 한 자릿수 더 낮다. 암모늄의 방출은 국부 pH를 더 높게 구동하는 경향이 있으며, 이에 의해 르샤틀리에(Le Chatelier)의 원리에 따라 질화규소와 물의 반응은 느려진다. 유기산의 첨가는 이 효과를 상쇄시킨다. 이는 pH를 더 낮게 구동하고, 방출된 암모늄 중 일부와 반응한다. 예로서 아세트산을 사용하여: CH₃CO₂H + NH₄OH

CH₃CO₂NH₄ + H₂O. 반응 생성물은 암모늄을 소비하고 물을 방출하여, 차례로 질화규소와의 반응을 가속화한다. 따라서, 유기산을 국부 환경에 첨가하면 암모늄의 농도를 감소시키고, 이렇게 함으로써, 질화규소와 물의 반응은 증가하는 경향이 있다. 이어서 또한 르샤틀리에의 원리에 따라 더 많은 암모늄이 방출된다. 이는 질화규소를 효과적으로 활성화시킨다. 점점 더 많은 물과 반응하여 점점 더 많은 암모니아 및 암모늄을 형성한다. 이들 모이어티의 방출은 질화규소의 항병원성 효과 이면에 있는 기본적인 메커니즘이다. 또한, 이들 유기산(예를 들어, 시트르산)은 질화규소와의 전술한 반응에 관계 없이 그들 자체의 항병원성 능력을 나타낼 수 있지만 주요 목적은 이전에 언급된 바와 같이 질화규소를 활성화시키는 것이다. 마지막으로, 약한 유기산의 사용은 낮은 농도 및 먹을 수 있는 형태로 인해 마스크 착용자에게 임의의 생체적합성 또는 건강 위험을 생성하지 않는다.Inclusion of one or a combination of these organic acids and complex mixtures with silicon nitride activates silicon nitride to release ammonia (NH ₃ ) by acidifying the local environment. Without being bound by theory, during normal breathing of a mask wearer, moisture passes through the mask during exhalation and inhalation. Moisture partially solubilizes organic acids. It dissociates into base and hydronium ions. Using acetic acid as an example, the reaction is: CH ₃ CO ₂ H + H ₂ O

CH ₃ CO ₂ ^- + H ₃ O ⁺ . This reaction reduces the local pH, creating an acidic environment in the vicinity of the silicon nitride particles. At the same time, a chemical reaction takes place at the surface of silicon nitride in the presence of ammonia and moisture releasing ammonium as follows: Si ₃ N ₄ + 16H ₂ O

3Si(OH) ₄ + 4NH ₄ OH

4NH ₃ + 4H ₂ O. At equilibrium, the concentrations of ammonium and ammonia depend on pH. As the pH increases, the amount of ammonium eluted from the silicon nitride decreases. While the corresponding amount of eluted ammonia increases, its concentration is an order of magnitude lower than that of ammonium. The release of ammonium tends to drive the local pH higher, thereby slowing down the reaction of silicon nitride with water according to Le Chatelier's principle. Addition of an organic acid counteracts this effect. This drives the pH lower and reacts with some of the released ammonium. Using acetic acid as example: CH ₃ CO ₂ H + NH ₄ OH

CH ₃ CO ₂ NH ₄ + H ₂ O. The reaction products consume ammonium and release water, which in turn accelerates the reaction with silicon nitride. Thus, adding an organic acid to the local environment reduces the concentration of ammonium, and by doing so, the reaction of silicon nitride with water tends to increase. Then more ammonium is released, also according to Le Chatelier's principle. This effectively activates the silicon nitride. It reacts with more and more water to form more and more ammonia and ammonium. The release of these moieties is the fundamental mechanism behind the antipathogenic effect of silicon nitride. In addition, these organic acids (eg citric acid) may exhibit their own anti-pathogenic ability regardless of their aforementioned reaction with silicon nitride, but their main purpose is to activate silicon nitride as previously mentioned. Finally, the use of weak organic acids does not create any biocompatibility or health risks to mask wearers due to their low concentrations and edible form.

In some embodiments, the layer with silicon nitride can inactivate viruses that come into contact with the layer of the antiviral face mask. For example, virus-containing droplets or aerosols are captured by the mask fibers and the silicon nitride powder inactivates them. Non-limiting examples of viruses that can be inactivated or prevented from spreading through a face mask include coronavirus, SARS-CoV-2, influenza A, influenza B, enterovirus, and feline calicivirus. The virus may be contacted with the silicon nitride powder for at least 30 seconds, at least 1 minute, at least 2 minutes, at least 3 minutes, at least 4 minutes, at least 5 minutes, at least 30 minutes, at least 1 hour, or at least 2 hours to be inactivated.

In another embodiment, the silicon nitride powder can be incorporated into a composition including, but not limited to, a slurry, suspension, gel, spray, paint, or toothpaste. For example, adding silicon nitride to a paint-like slurry that is then applied to the surface can provide an antibacterial, antifungal, and antiviral surface. In another embodiment, silicon nitride can be mixed with water along with any suitable dispersants and slurry stabilizers and then applied by spraying the slurry onto various surfaces.

In an example, the antipathogenic composition may be a slurry of silicon nitride powder and water. Silicon nitride powder may be present in the slurry at a concentration of about 0.1 vol.% to about 20 vol.%. In various embodiments, the slurry is about 0.1 vol.%, 0.5 vol.%, 1 vol.%, 1.5 vol.%, 2 vol.%, 5 vol.%, 10 vol.%, 15 vol.%, or 20 vol.% silicon nitride.

Further provided herein is a method of inactivating a pathogen by contacting a virus, bacteria, and/or fungus with an antipathogenic composition comprising silicon nitride. In an embodiment, a method may include coating a device or instrument with silicon nitride and contacting the coated instrument with a virus, bacteria, or fungus. Coating the appliance may include applying silicon nitride powder to the surface of the appliance. In another embodiment, the silicon nitride powder can be incorporated into or impregnated into a device or appliance.

Without being limited to a particular theory, the anti-pathogenic composition may reduce viral action by alkaline transesterification and reduce the activity of hemagglutinin. Surprisingly, silicon nitride powder (i) significantly reduces viral action by alkali transesterification through breakage of RNA internucleotide bonds and (ii) significantly reduces hemagglutinin activity to denature the protein structure on the surface of the virus. It has been found that disrupting host cell recognition results in inactivation of the virus regardless of the presence of a viral envelope.

In embodiments, the antipathogenic composition may exhibit elution kinetics exhibiting: (i) slow but continuous elution of ammonia from the solid state rather than the usual gas phase; (ii) no damage or adverse effects on mammalian cells; and (iii) intelligent elution that increases with decreasing pH. Moreover, the inorganic properties of silicon nitride may be more beneficial than the use of petrochemical or organometallic fungicides, viricides, and fungicides that are known to harm mammalian cells or have residual effects in soil, plants, and vegetables or fruits. can

It has also surprisingly been found that silicon nitride particles can be electrically attracted and attached to spike proteins on the envelope or membrane of pathogens.

Also provided herein are methods for lysing or inactivating pathogens located in human patients. For example, the pathogen may be a virus, bacterium, or fungus. The method may include contacting the patient with a device, appliance, or composition comprising silicon nitride. Without being limited by any one theory, silicon nitride inactivates pathogens. The device, apparatus, or composition may include from about 1 wt.% to about 100 wt.% silicon nitride. In some examples, a device or appliance may include from about 1 wt.% to about 100 wt.% silicon nitride on a surface of the device or appliance. In an embodiment, the device or apparatus may be a monolithic silicon nitride ceramic. In another embodiment, the device or appliance may include a silicon nitride coating, such as a silicon nitride powder coating. In another embodiment, the device or appliance may incorporate silicon nitride into the body of the device. For example, silicon nitride powder may be incorporated or impregnated into the body of a device or appliance using methods known in the art.

In some implementations, the device or instrument can be in contact with the patient or user for at least 1 minute, at least 5 minutes, at least 30 minutes, at least 1 hour, at least 2 hours, at least 5 hours, or at least 1 day. In at least one example, the device or appliance may be permanently implanted in a patient. In at least one example, the device or appliance may be worn externally by a user.

Example

Example 1: Effect of silicon nitride concentration on virus inactivation

To show the effect of silicon nitride concentration on virus inactivation, influenza A was exposed to various concentrations of Si ₃ N ₄ powder. To produce silicon nitride, a certain weight of silicon nitride powder is mixed with pure distilled water. For example, 7.5 g of silicon nitride was dispersed in 92.5 g of pure distilled water. Virus was added to this mixture at concentrations of 1:1, 1:10 and 1:100 virus/mixture, respectively. These mixtures were then allowed to incubate at 4° C. for 10 minutes under gentle agitation. Influenza A was exposed to 0 wt.%, 7.5 wt.%, 15 wt.%, and 30 wt.% Si ₃ N ₄ at 4° C. for 10 minutes, as illustrated in FIG. 2A. The mixture was then filtered to remove the silicon nitride powder.

Influenza A virus-inoculated distal tubule (MDCK) cells were then observed for the effect of Si ₃ N ₄ to inactivate influenza A. The remaining mixture was then inoculated into Petri dishes containing live MDCK cells in biogenic medium. Subsequently, the amount of live MDCK cells was counted using the staining method after 3 days of exposure. The viability of MDCK cells was determined after inoculation of the cells with influenza A exposed to Si ₃ N ₄ for 3 days according to FIG. 2B .

4A is a graph of PFU/100 μl for Influenza A exposed to 0 wt.%, 7.5 wt.%, 15 wt.%, and 30 wt.% Si ₃ N ₄ for 10 minutes. 4B is a graph of cell viability of cells inoculated with influenza A exposed to 7.5 wt.%, 15 wt.%, and 30 wt.% Si ₃ N ₄ for 10 minutes.

Example 2: Effect of exposure time and temperature on viral inactivation

To show the effect of silicon nitride on virus inactivation, influenza A was exposed to a fixed concentration of Si ₃ N ₄ powder (15 wt.%) for various times and temperatures. The mixture was then allowed to incubate at room temperature and 4° C. for 1-30 minutes under gentle agitation. For example, influenza A was exposed to 15 wt.% Si ₃ N ₄ for 1, 5, 10, or 30 minutes at room temperature or 4° C., as illustrated in FIG. 3A . Influenza A virus-inoculated distal tubule (MDCK) cells were then observed for the effect of Si ₃ N ₄ to inactivate influenza A. The viability of MDCK cells was determined after inoculation of the cells with influenza A exposed to Si ₃ N ₄ for 3 days according to FIG. 3B .

7A is a graph of PFU/100 μl for influenza A exposed to 15 wt.% Si ₃ N ₄ for 1 minute, 5 minutes, 10 minutes, or 30 minutes at room temperature. 7B is a graph of cell viability of MDCK cells inoculated with influenza A exposed to 15 wt.% Si ₃ N ₄ for 1 minute, 5 minutes, 10 minutes, or 30 minutes at room temperature.

8A is a graph of PFU/100 μl for influenza A exposed to 15 wt.% Si ₃ N ₄ for 1 minute, 5 minutes, 10 minutes, or 30 minutes at 4° C. FIG. FIG. 8B is a graph of MDCK cell viability inoculated with influenza A exposed to 15 wt.% Si ₃ N ₄ at 4° C. for 1 minute, 5 minutes, 10 minutes, or 30 minutes.

Example 3: Effect of silicon nitride on H1H1 influenza A inactivation

To show the effect of silicon nitride on virus inactivation, influenza A was exposed to a slurry of 15 wt.% silicon nitride for 10 minutes.

15A - 15C show H1H1 staining red (nucleoprotein, NP) after inoculation into biogenic medium containing MDCK cells stained green for the presence of the filamentous actin (F-actin) protein found in all eukaryotic cells. Influenza A virus (A/Puerto Rico/8/1934 H1N1 (PR8)). 16A - 16C show the effect of viruses on MDCK cells in the absence of silicon nitride.

Example 4: Evaluation of influenza A virucidal activity by silicon nitride in MDCK cells

This study was designed to investigate the antiviral ability of beta-silicon nitride (β-Si ₃ N ₄ ) powder against influenza A at a concentration of 15 wt.%/vol and at an incubation time point of 30 minutes. A 15 wt.% suspension was prepared from 1.5 mL of virus diluted in DMEM without additives.

A plaque assay methodology was utilized. To adequately quantify the plaque assay, viability of distal tubule cells (MDCK) was assessed as a function of exposure to various concentrations of Si ₃ N ₄ for incubation periods ranging from 30 minutes to 72 hours. Results demonstrated that Si ₃ N ₄ was completely virucidal against influenza A with >99.98% reduction in viral load under preselected conditions. The viability of MDCK cells was found to be time- and dose-dependent. Essentially no loss of viability was observed for Si ₃ N ₄ concentrations up to 15 wt.%/vol. Changes in viability were noted only for the 15 wt.% concentration at 24, 48, and 72 hours (i.e., 83.3%, 59.7%, and 44.0% viability, respectively).

The Si ₃ N ₄ powder used in this study had a nominal composition of 90 wt.% α -Si ₃ N ₄ , 6 wt.% yttria (Y ₂ O ₃ ), and 4 wt.% alumina (Al ₂ O ₃ ). had This is achieved by aqueous mixing and spray drying of the inorganic constituents, followed by sintering of the spray dried granules (~1700°C for ~3 hours), hot isostatic pressing (~1600°C, 2 hours, 140 MPa in N ₂ ), and aqueous It was prepared by pulverizing the -base and freeze-drying it. The resulting powder had a trimodal distribution with an average particle size of 0.8±1.0 μm as shown in FIG. 17 . Doping Si ₃ N ₄ with Y ₂ O ₃ and Al ₂ O ₃ is useful for increasing the density of ceramics and converting α-phase to β-phase during sintering. The densification mechanism is carried out through the dissociation of the α-phase and the subsequent precipitation of the β-phase grains, facilitated by the formation of a transient intergranular liquid that hardens during cooling. Thus, β-Si ₃ N ₄ is a composite material composed of about 10 wt.% intergranular glass phase (IGP) and 90 wt.% crystalline β-Si ₃ N ₄ grains.

Three sequential assays were performed in this study: (1) MDCK viability test; (2) Influenza A supernatant titration test with or without centrifugation and filtration; and (3) virus titration using 15 wt.%/vol Si ₃ N ₄ as virus inhibitor for an incubation period of 30 m.

In FIG. 18 , viability of MDCK cells is presented as a function of β-Si ₃ N ₄ concentration (wt.%/mL). Starting at 15 wt.%, serial dilutions were performed to reach 0.047 wt.%. At lower concentrations, cell viability was generally >80% for all time points up to 72 hours. Also note that cell viability generally increased with exposure time for all concentrations except 15 wt.%. Cell viability was -94.5% at 15 wt.% and 30-minute exposure.

After MDCK cell viability determination, 24 h prior to addition of virus and samples to the cells, MDCK cells were cultured at 1 x 10 ⁶ cells in a 2 mL volume in Dulbecco's Minimum Essential Medium (DMEM) supplemented with 10% fetal bovine serum (FBS). Plated in 6-well plates at a density of cells/well. On the day of assay, triplicate samples of 15 wt.% silicon nitride in virus diluted in DMEM without additives at 1 x 10 ⁴ PFU/mL were incubated for 30 minutes at room temperature with shaking. After incubation, samples were centrifuged at 4° C. and 12,000 rpm for 2 minutes and further filtered through a 0.2-micron polyvinylidene difluoride (PVDF) filter. Samples were then serially diluted 1:5 and 7 concentrations were added in triplicate in 400 μL volumes to cells washed twice with Dulbecco's Phosphate Buffered Saline (DPBS). Samples were incubated at 37° C. for 1 hour with shaking every 15-20 minutes. After incubation, 2 mL of plaque assay medium was added to the wells and the cultures were incubated at 35° C./5% CO ₂ for 48 hours. After incubation, cells were stained with crystal biolette and plaques were visually enumerated.

On the day of staining, plaque medium was removed and monolayers were washed twice with DPBS. Cells were then fixed with 70% ethanol for 10 min at room temperature. Ethanol was removed, and a 0.3% crystal violet solution was added to each well for 10 minutes at room temperature. After this incubation, the crystal violet was removed and the monolayer was washed twice with DPBS to remove residual crystal violet. Monolayers were air-dried overnight before plaques were counted.

Viricidal tests were performed at a concentration of 15 wt.%/vol and 30 minutes. The process steps of centrifugation and filtration only reduced the viral load by about 0.25 log ₁₀ . Taking this result into account, subsequent titrations were then performed with or without exposure of the virus to Si ₃ N ₄ for 30 minutes. The concentration for the titration without Si ₃ N ₄ was chosen a priori to be 4.4 x 10 ³ pfu/ml based on ISO 21702 ( Determination of antiviral activity on plastics and other non-porous surfaces ). After 30 minutes of exposure to Si ₃ N ₄ , no plaques were formed on the MDCK cells. Si ₃ N ₄ was considered 100% effective in inactivating influenza A. A direct comparison of viral titers before and after exposure to Si ₃ N ₄ powder for 30 m is provided in FIG. 19 . The data clearly demonstrate a >3.5 log ₁₀ reduction (ie >99.98%) of viral load after exposure to Si ₃ N ₄ .

In summary, these tests demonstrated that exposure of Si ₃ N ₄ to MDCK cells did not adversely affect viability at concentrations less than 15 wt.%/vol or for periods of ≤ 30 minutes. In antiviral test conditions of 15 wt.%/vol Si ₃ N ₄ at 30 min exposure at a load of 4.4 x 10 ³ pfu/ml, Si ₃ N ₄ essentially inactivated 100% of the exposed virions. Si ₃ N ₄ was found to be virucidal against influenza A under these conditions.

Example 5: α-Si against MDCK cells and influenza A ₃ N ₄ effect of powder

α-Si ₃ N ₄ powders were first evaluated for toxicity to MDCK cells after exposure for 30 minutes, 24 hours, 48 hours and 72 hours. A 15% by weight (wt.%) suspension was prepared in 1.5 mL of Dulbecco's modified Eagle's medium (DMEM) supplemented with 2% fetal bovine serum (FBS).

Twenty-four hours before adding the samples to the cells, the α-Si ₃ N ₄ powder suspension prepared as described above was incubated for 30 minutes at room temperature with shaking. After incubation, the suspension was centrifuged for 2 minutes at 12,000 rpm at 4°C. The supernatant was further filtered through a 0.2-micron polyvinylidene difluoride (PVDF) filter and then serially diluted in half-log increments. Six concentrations were added to the pre-plated cells in triplicate in a volume of 200 μL. The plates were incubated for 30 minutes, 24, 48, and 72 hours at which time the cells were inoculated with the tetrazolium dye XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5- as described below. [(phenylamino)carbonyl]-2H-tetrazolium hydroxide) was used to evaluate for cytotoxicity.

TC50 values for the test materials were derived by measuring the reduction of the tetrazolium dye XTT. XTT in metabolically active cells is metabolized to soluble formazan products by the mitochondrial enzyme NADPH oxidase. XTT solutions were prepared daily as stocks of 1 mg/mL in DMEM without additives. A solution of phenazine methosulfate (PMS) was prepared at 0.15 mg/mL in Dulbecco's Phosphate Buffered Saline (DPBS) and stored in the dark at -20°C. XTT/PMS stocks were prepared by adding 40 μL of PMS per mL of XTT solution immediately prior to use. 50 μL (50 4 ) of XTT/PMS was added to each well of the plate and the plate was incubated at 37° C. for 4 hours. A 4-hour incubation was empirically determined to be within the linear response range for XTT dye reduction according to the indicated number of cells for each assay. The plate was sealed and inverted several times to mix the soluble formazan product and the plate was read on a Molecular Devices SpectraMax Plus 384 96 well plate format spectrophotometer at 450 nm (650 nm reference wavelength).

MDCK cells were treated with 15 wt.% to 0.047 wt. It was treated with α-Si ₃ N ₄ powder at 6 concentrations in the % range. In FIG. 20 , viability of MDCK cells is presented as a function of α-Si ₃ N ₄ concentration (wt.%/mL). Cells treated with all concentrations after 30 minutes of exposure had viability greater than 90%, except for cells treated with 4.7 wt.% and 15 wt.%, which had 89% and 83% viability, respectively. At 24 hours, the viability of cells treated with each concentration remained above 92%. At 48 h, viability fell to less than 90% in cells treated with 1.5 wt.%, 4.7 wt.%, and 15 wt.% (89.1%, 88.7%, and 74.0%, respectively), but at 72 h, 15 wt. % only had viability less than 90% (87.5%).

The α-Si ₃ N ₄ powder was then evaluated for viricidal activity against influenza A strain A/PR/8/34 in MDCK cells. A 15 wt.% suspension was prepared from 1.5 mL of virus diluted in DMEM without additives.

24 h before adding virus and samples to the cells, MDCK cells were grown at a density of 1 x 10 ⁶ cells/well in a volume of 2 mL in Dulbecco's Minimum Essential Medium (DMEM) supplemented with 10% fetal bovine serum (FBS). Plated in 6-well plates. On the day of assay, triplicate samples of 15 wt.% α-Si ₃ N ₄ in virus diluted in DMEM without additives at 1×10 ⁴ PFU/mL were incubated for 30 minutes at room temperature with shaking. After incubation, samples were centrifuged at 4° C. and 12,000 rpm for 2 minutes and further filtered through a 0.2-micron polyvinylidene difluoride (PVDF) filter. Samples were then serially diluted 1:5 and 7 concentrations were added in triplicate in 400 mL volumes to cells washed twice with Dulbecco's Phosphate Buffered Saline (DPBS). Samples were incubated at 37° C. for 1 hour with shaking every 15-20 minutes. After incubation, 2 mL of plaque assay medium was added to the wells and the cultures were incubated at 35° C./5% CO ₂ for 48 hours. After incubation, cells were stained with crystal violet and plaques were visually enumerated.

On the day of staining, plaque medium was removed and monolayers were washed twice with DPBS. Cells were then fixed with 70% ethanol for 10 min at room temperature. Ethanol was removed, and a 0.3% crystal violet solution was added to each well for 10 minutes at room temperature. After this incubation, the crystal violet was removed and the monolayer was washed twice with DPBS to remove residual crystal violet. Monolayers were air-dried overnight before plaques were counted.

The viricidal activity of 15 wt.% α-Si ₃ N ₄ powder was evaluated against influenza virus A strain A/PR8/34 in MDCK cells. The target virus titer was 1 x 10 ⁴ PFU/mL and the actual individual replicates were 3.1 x 10 ³ , 3.8 x 10 ³ , and 4.7 x 10 ³ PFU/mL, with an average titer of 3.9 x 10 ³ ± 0.8 x 10 ³ PFU/mL. (and standard deviation) was calculated. This actual titer is within 2-fold of the targeted PFU/mL. The α-Si ₃ N ₄ powder treated sample had one well with a single plaque and resulted in a PFU/mL of 4.1.

The log reduction was 2.98 and was calculated using the equation: log ₁₀ (A/B) where A is the untreated virus and B is the treated virus. The reduction was 99.89% and was calculated using the following equation: (AB) x 100/A where A is the untreated virus and B is the treated virus. A comparison of viral titers before and after exposure to α-Si ₃ N ₄ powder for 30 minutes is provided in FIG. 21 . Thus, 15 wt.% of α-Si ₃ N ₄ powder was virucidal against influenza A virus strain A/PR/8/34 after 30-minute exposure.

Example 6: Si in MDCK cells ₃ N ₄ Influenza A viricidal activity by two forms of powder

5 and 10 wt.% suspensions of α-Si ₃ N ₄ and β-Si ₃ N ₄ powders were prepared in 1.5 mL of virus diluted in DMEM without additives.

24 h before adding virus and samples to the cells, MDCK cells were grown at a density of 1 x 10 ⁶ cells/well in a volume of 2 mL in Dulbecco's Minimum Essential Medium (DMEM) supplemented with 10% fetal bovine serum (FBS). Plated in 6-well plates. On the day of the assay, triplicate samples of 10 and 5 wt.% of α-Si ₃ N ₄ and β-Si ₃ N ₄ powders in virus diluted in DMEM without additives at 1 x 10 ⁴ PFU/mL were incubated at room temperature with shaking. Incubated for 30 minutes. After incubation, samples were centrifuged at 4° C. and 12,000 rpm for 2 minutes and further filtered through a 0.2-micron polyvinylidene difluoride (PVDF) filter. Samples were then serially diluted 1:5 and 7 concentrations were added in triplicate in 400 μL volumes to cells washed twice with Dulbecco's Phosphate Buffered Saline (DPBS). Samples were incubated at 37° C. for 1 hour with shaking every 15-20 minutes. After incubation, 2 mL of plaque assay medium was added to the wells and the cultures were incubated at 35° C./5% CO ₂ for 48 hours. After incubation, cells were stained with crystal violet and plaques were visually enumerated.

On the day of staining, flagging medium was removed and monolayers were washed twice with DPBS. Cells were then fixed with 70% ethanol for 10 min at room temperature. Ethanol was removed, and a 0.3% crystal violet solution was added to each well for 10 minutes at room temperature. After this incubation, the crystal violet was removed and the monolayer was washed twice with DPBS to remove residual crystal violet. Monolayers were air dried overnight before plaques were counted.

The viricidal activity of 5 and 10 wt.% of α-Si ₃ N ₄ and β-Si ₃ N ₄ powders was evaluated against influenza virus A strain AIPR8/34 in MDCK cells. This was done in 4 separate experiments. The target virus titer was 1 x 10 ⁴ PFU/mL.

In the first experiment, individual replicates for untreated virus samples were 5.3 x 10 ³ , 5.9 x 10 ³ , and 4.1 x 10 ³ PFU/mL, with an average titer of 5.1 x 10 ³ ± 0.9 x 10 ³ PFU/mL (and standard deviation) was calculated. Viruses treated with 5 wt.% and 10 wt.% of β-Si ₃ N ₄ for 10 minutes resulted in PFU/mL of < 21 for viruses treated with 10 wt.% and 5 wt.%. The virus resulted in a PFU/mL of 21 (1 plaque formed). For this sample, the log reduction was 2.4 and was calculated using the equation: log10(NB) where A is the untreated virus and B is the treated virus. The reduction was 99.5% and was calculated using the equation: (AB) x 100/A where A is the untreated virus and B is the treated virus.

In the second experiment, individual replicates for untreated virus samples were 7.5 x 10 ³ , 7.2 x 10 ³ , and 5.0 x 10 ³ PFU/mL, with an average titer of 6.6 x 10 ³ ± 1.4 x 10 ³ PFU/mL (and standard deviation) was calculated. Viruses treated with 5 wt.% and 10 wt.% of β-Si ₃ N ₄ for 5 min both resulted in PFU/mL of <21.

In the third experiment, individual replicates were 6.9 x 10 ³ , 7.8 x 10 ³ , and 5.0 x 10 ³ PFU/mL, yielding mean titers (and standard deviations) of 6.6 x 10 ³ ± 1.4 x 10 ³ PFU/mL. Viruses treated with 5 wt.% and 10 wt.% of α-Si ₃ N ₄ for 10 min both resulted in PFU/mL of <21.

In the fourth experiment, individual replicates were 8.8 x 10 ³ , 1.0 x 10 ⁴ , and 7.5 x 10 ³ PFU/mL, yielding mean titers (and standard deviations) of 8.8 x 10 ³ ± 1.3 x 10 ³ PFU/mL. Viruses treated with 5 wt.% and 10 wt.% of α-Si ₃ N ₄ for 5 min both resulted in PFU/mL of <21.

The actual titer determined against the untreated virus control in each experiment was within 2-fold of the targeted PFU/mL. 5 and 10 wt for 5 and 10 min. % of the virus treated with both α-Si ₃ N ₄ and β-Si ₃ N ₄ powders for 10 min with β-Si ₃ N ₄ powder treated with 5 wt.% of the sample resulting in a PFU/mL of 21. Except having 1 well with a single plaque resulted in <1 PFU/mL (no plaque observed).

Example 7: Silicon nitride inactivation of SARS-CoV-2 in vitro

_{Doped Si 3 N 4 powder (} β- _{_} SiYAlON) is obtained by aqueous mixing and spray drying of the inorganic components, followed by sintering of the spray dried granules (~1700°C for ~3 hours) and hot isostatic pressing (~1600°C, 2 hours, 140 Mpa in N ₂ ). , prepared by grinding an aqueous base and freeze drying. The resulting powder had a trimodal distribution with an average particle size of 0.8 ± 1.0 μm as shown in FIG. 22 . Si ₃ N ₄ was doped with Y ₂ O ₃ and Al ₂ O ₃ to increase the density of the ceramic and convert α -phase to β -phase during sintering. The densification mechanism is carried out through dissociation of the α -phase and subsequent precipitation of the β -phase grains, facilitated by the formation of a transient intergranular liquid that hardens during cooling. Thus, β -Si ₃ N ₄ is a composite material composed of about 10 wt.% intergranular glass phase (IGP) and 90 wt.% crystalline β -Si ₃ N ₄ grains.

Vero green African monkey kidney epithelial cells were selected for this assay due to their ability to support high levels of SARS-CoV-2 replication and their use in antiviral testing. These cells were cultured in DMEM supplemented with 10% FBS, 1% L-glutamine, and 1% penicillin/streptomycin. cells 37° C. and 5% CO₂was maintained in SARS-CoV-2 isolate USA-WA1/2020 was obtained from BEI Resources. Viral stocks were generated by inoculating Vero cells with SARS-CoV-2 (MOI 0.1). Cell-free supernatants were collected 72 hours after infection and clarified by centrifugation at 10,000 rpm for 10 minutes and filtered through a 0.2 μm filter. Stock virus was titrated according to the plaque assay protocol detailed below.

Si ₃ N ₄ powder was suspended in 1 mL DMEM growth medium in a microcentrifuge tube. The tube was vortexed for 30 seconds to ensure proper contact and then placed on a tube spinner for 1, 5, or 10 minutes. At each time point, samples were centrifuged and the supernatant was collected and filtered through a 0.2 μm filter. Clarified supernatant was added to cells for 24 or 48 hours. Untreated cells were kept together as a control. Cell viability was determined by testing cells at each time point using CellTiter Glo, which measures ATP production.

SARS-CoV-2 was diluted in DMEM growth medium at a concentration of 2 x 10 ⁴ PFU/mL. 4 mL of diluted virus was added to tubes containing silicon nitride at 20, 15, 10, and 5% (w/v). A virus without Si ₃ N ₄ was treated simultaneously as a control. Virus only controls were incubated for up to 10 minutes, while the tubes were vortexed for 30 seconds to ensure proper contact and then placed on a tube spinner for 1, 5, or 10 minutes. At each time point, samples were centrifuged and the supernatant was collected and filtered through a 0.2 μm filter. Infectious virus remaining in the clarified supernatant was quantified by plaque assay. An overview of the antiviral testing method is provided in FIG. 23 . In step 1, the SARS-CoV-2 virus was diluted in medium. In step 2, 4 mL of diluted virus was added to a tube containing silicon nitride at 20, 15, 10, or 5% (w/v). In step 3, the tube was vortexed for 30 seconds to make proper contact and placed on a tube spinner for 1 m, 5 m, or 10 m (virus only control was incubated for up to 10 minutes). In step 4, at each time point, the samples were centrifuged and the supernatant was collected and filtered through a 0.2 μm filter. In step 5, a plaque assay was performed using the clarified supernatant. Samples were serially diluted (10-fold) and added to fresh Vero for 1 hour incubation, ricking every 15 minutes before addition to agarose medium overlay and incubated for 48 hours. After 48 hours incubation, cells were fixed with 10% FA and stained with crystal violet for counting.

Vero cells were plated at 2×10 ⁵ cells/well in 12-well plates the day before the plaque assay. The clarified supernatant from the antiviral test was serially diluted (10-fold) and 200 μL was added to Vero cells and incubated for 1 hour at 37° C., 5% CO ₂ . Shake the plate every 15 min to ensure sufficient coverage and a 1:1 ratio of 0.6% agarose at 1 h and add 5% FBS, 2% Penicillin/Streptomycin, 1% Nonessential Amino Acids (VWR, Cat # 45000-700) , 1% sodium pyruvate, and 2X EMEM supplemented with 1% L-glutamine were added to the cells and then incubated at 37° C., 5% CO ₂ for 48 hours. After incubation, cells were fixed with 10% formaldehyde and stained with 2% crystal violet in 20% ethanol for counting.

The effect of Si ₃ N ₄ on eukaryotic cell viability was tested. Si ₃ N ₄ was resuspended in cell culture medium at 5, 10, 15, and 20% (w/v). Samples were collected at 1, 5, and 10 minutes and added to Vero cells. Vero cell viability was measured at 24 and 48 hours post exposure ( FIGS. 24A and 24B ). No significant decrease in cell viability was observed at 24 or 48 hours after exposure to 5%, 10%, or 15% silicon nitride. A small effect (~10% reduction) on cell viability was observed at 48 h in cells exposed to 20% Si ₃ N ₄ . Interestingly, a ~10% increase in Vero cell viability was observed at 48 hours in the 5% - 10 min and 10% - 10 min samples ( FIG. 24B ), indicating that Si ₃ N ₄ inhibits cell growth or cell metabolism under these conditions. suggests that it can be stimulating. These data indicated that Si ₃ N ₄ had minimal effect on Vero cell health and viability up to 20 wt.%/vol.

Considering that 5, 10, 15, and 20% Si ₃ N ₄ are non-toxic to Vero cells, antiviral tests were performed at these concentrations. SARS-CoV-2 virions were exposed to Si ₃ N ₄ at these concentrations for 1, 5, or 10 minutes. After Si ₃ N ₄ exposure, the infectious virus remaining in each solution was determined by plaque assay. At each time point, samples were centrifuged and the supernatant was collected and filtered through a 0.2um filter. Plaque assays were performed in duplicate using clarified supernatants. Viruses treated concurrently but exposed only to the cell culture medium contained 4.2 x 10 ³ PFU/mL. SARS-CoV-2 titers decreased when exposed to all concentrations of Si ₃ N ₄ tested ( FIGS. 25A and 25B ). Inhibition was achieved with SARS-CoV-2 exposed for 1 minute and 5% Si ₃ N ₄ with viral titers reduced by -0.8 log ₁₀ , 10% Si ₃ N ₄ by -1.2 log ₁₀ , 15 -1.4 log ₁₀ % Si ₃ N ₄ , and dose dependent at 20% Si ₃ N ₄ up to 1.7 log ₁₀ ( FIG. 25A ). Similar results were observed for 5 and 10 min samples. This reduction in viral titer was 85% viral inhibition at 5% Si ₃ N ₄ , 93% at 10% Si ₃ N ₄ , 96% at 15% Si ₃ N ₄ , and 98% viral inhibition at 20% Si ₃ N ₄ . Corresponded to (Fig. 25b ). Higher Si ₃ N ₄ concentrations for longer periods of time resulted in increased inhibition resulting in 99.6% viral inhibition at 20% Si ₃ N ₄ and 10 min exposure ( FIG. 25B ). These data indicate that Si ₃ N ₄ has a strong antiviral effect against SARS-CoV-2.

A surprising finding was that 1 minute exposure to a 5% solution of Si ₃ N ₄ resulted in 85% inactivation of SARS-CoV-2, whereas Vero cell viability was minimally affected even after 48 hours exposure to the same material at 20% concentration. it was crazy

Example 8: Silicon nitride embedding in fabric

Pretreatment

Two sequential steps were performed for pretreatment. In a first step, the scrim segments were pre-cleaned by stirring in a heated cover tank containing deionized water for 10 minutes (90 °C ≤ T ≤ 100 °C). After washing, the scrim was air dried. This step tends to remove the organic compounds used to make the fabric along with any loosely attached contaminants due to transport and storage. The use of detergent was avoided to prevent interference with the coupling agent. In a second step, the fabric was immersed in a room temperature water bath under agitation. Due to their hydrophobic properties, scrims must be kept under water. This was done by placing the fabric in a covered 304 stainless steel basket. An organic surfactant (i.e. coupling agent) was added to the bath. The surfactant used was n-dodecyl trimethyl ammonium bromide (DTAB). The amount of DTAB added is based on the weight of the scrim to be treated using the following calculation: DTAB weight (g) = scrim weight (g) x 1.73. After adding DTAB, the bath temperature was increased to 100° C. (boiling) and held at this temperature for 30 minutes. The scrim was then removed from the bath and laid flat to dry in a circulating air oven at 110° C. for 10 minutes.

landfill process

The landfill process utilized three process steps. The first step involved preparing a dispersion of Si ₃ N ₄ powder in deionized water. This was achieved by metering out the water, organic dispersant, and Si ₃ N ₄ into a vibrator or ball mill and stirring the ingredients for a minimum of 30 minutes. Dispersion can also be carried out using high intensity shear mixers (i.e., propeller action) for approximately the same amount of time. The composition of the dispersion was as follows (based on ~1 liter batch size): 210.0 g Si ₃ N ₄ powder, 2.1 g Dolapix A88 dispersant, and 790.0 g deionized water.

The second step is to siphon the Si ₃ N ₄ dispersion (i.e. slurry) into a manual HTE compliant spray gun and apply approximately 0.45 ml/cm ² at a pressure of approximately 30 psi (2.1 bar, 210 kPa) and a distance of approximately 0.5 meters. It involves manual application uniformly to one side of the pretreated fabric at speed. After air drying for about 10 minutes, the opposite side of the scrim was then coated in the same manner. The spraying process was then repeated again (i.e., 2 applications per side). The third step involved immersing the coated scrim in the residual Si ₃ N ₄ slurry in a Branson laboratory ultrasonic bath for 10 minutes at a temperature of 65 °C ≤ T ≤ 75 °C and a power setting of about 60 W and 20 kHz. The fabric was then pushed through a ringer to remove excess slurry and placed flat in a drying oven at -110°C for about 10 minutes.

thermal bonding

Bonding of the Si ₃ N ₄ particles to the scrim was achieved by placing a single sheet of fabric between two precision heavy duty stainless steel plates in an oven at a temperature of 145° C. for 90 minutes. The process produced a pressure of about 0.1 psi (~0.7 kPa) on the fabric. This pressure was very important in forcing the embedding of the Si ₃ N ₄ particles in the polypropylene fibers. The plate containing the fabric was then removed from the oven and allowed to cool to room temperature.

washing and rinsing

Rinsing was an important step. This removed unbonded Si ₃ N ₄ particles from the fabric. This was done in a two-step operation. The first step involved washing the buried scrim in deionized water using a non-ionic surfactant in a Branson laboratory ultrasonic bath operating at about 60 W and a power setting of 20 kHz. The composition of this washing step was (based on 1 liter batch size): 10.0 g Triton X-100 surfactant and 990.0 g deionized water.

After preparing the washing bath, the fabric was immersed and sonicated at 60 °C ≤ T ≤ 70 °C for 5 minutes. The scrim was then pulled through a ringer to remove excess liquid. The second step involved rinsing the scrim in clean deionized water. This was also achieved in an ultrasonic bath at 60 °C ≤ T ≤ 70 °C with a power setting of about 60 W and 20 kHz for 5 minutes. Repeated rinse cycles were often performed until the rinse water was clear.

dry

The cleaned and rinsed fabric was dried by simply laying flat on a drying oven rack at about 110° C. for approximately 10 minutes.

While several embodiments have been described, it will be recognized by those skilled in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be taken as limiting the scope of the present invention.

Those skilled in the art will appreciate that the presently disclosed implementations are taught by way of example and not limitation. Accordingly, the matter contained in the foregoing description and presented in the accompanying drawings is to be interpreted in an illustrative rather than a limiting sense. The following claims are intended to cover all general and specific features described herein, as well as all statements as to the scope of the methods and systems that may be said to fall therebetween as a matter of language.

Claims (20)

As an antiviral face mask,
A face mask body comprising a layer of fibrous material comprising silicon nitride powder embedded in a fibrous material, wherein the silicon nitride is present on the inner surface at a concentration of about 1 wt.% to about 15 wt.%;
wherein the silicon nitride inactivates viruses that come into contact with the layers of the face mask body. The antiviral face mask of claim 1 , further comprising a second layer of material surrounding the fibrous material. The antiviral face mask of claim 1 , wherein the fibrous material comprises a spunbond nonwoven fabric. 4. The antiviral face mask of claim 3, wherein the spunbond nonwoven fabric comprises polypropylene. 2. The antiviral face mask of claim 1, wherein the virus-containing droplets or aerosols are entrapped by fibers within the fiber material to contact the virus with the silicon nitride embedded in the fiber material and the silicon nitride powder inactivates the virus. The antiviral face mask of claim 1 , wherein the virus is contacted with the silicon nitride powder for a period of at least 1 minute. The antiviral face mask of claim 1 , wherein the silicon nitride in the layer of fibrous material is present in a concentration of less than about 10 wt.%. The antiviral face mask of claim 1 , wherein the virus is SARS-CoV-2. As an antiviral face mask,
face mask body; and
one or more filters of the face mask body, each of the one or more filters
a fibrous material layer comprising silicon nitride powder impregnated in the fibrous material layer, wherein the silicon nitride is present in a concentration of about 1 wt.% to about 15 wt.%;
wherein the silicon nitride inactivates viruses that come into contact with the at least one filter of the antiviral face mask. 10. The antiviral face mask of claim 9, wherein the fibrous material comprises a spunbond nonwoven fabric. 11. The antiviral face mask of claim 10, wherein the spunbond nonwoven fabric comprises polypropylene. 10. The antiviral face mask of claim 9, wherein the virus-containing droplets or aerosols are captured by the fiber material to contact the virus with the silicon nitride embedded in the fiber material and the silicon nitride powder inactivates the virus. 10. The antiviral face mask of claim 9, wherein the virus is contacted with the silicon nitride powder for a period of at least 1 minute. 10. The antiviral face mask of claim 9, wherein the silicon nitride in each filter is present in a concentration of less than about 10 wt.%. The antiviral face mask of claim 1 , wherein the virus is SARS-CoV-2. As a method of preventing virus transmission,
A method comprising providing the antiviral face mask of claim 1 to a wearer, wherein the silicon nitride powder inactivates the virus when it contacts the fibrous material of the face mask. As a method of embedding silicon nitride powder in a fiber material,
pre-treating the fibrous material in at least one pre-treatment tank;
embedding silicon nitride particles in the fibrous material using sonication in an ultrasonic tank;
drying the fibrous material and thermally bonding the silicon nitride particles in a drying and thermal bonding oven;
rinsing the fibrous material in an ultrasonic rinse tank to remove excess silicon nitride particles; and
drying the rinsed fibrous material in a drying oven. 18. The method of claim 17, wherein the at least one pre-treatment tank comprises a plurality of ultrasonic transducers and contains water and/or a coupling agent. 18. The method of claim 17, wherein the ultrasonic tank includes a plurality of ultrasonic transducers and contains water, a dispersant, and silicon nitride particles. 18. The method of claim 17, wherein the ultrasonic rinse tank comprises multiple ultrasonic transducers and contains water and a surfactant.

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