# Nanotechnology-Enhanced Face Masks: Future Scopes and Perspectives

Authors: Ashraf Maher; Mohamed S. Abdo; Hany S. Abdo
Journal: Advances in Materials Science and Engineering
 (2022)

---

## Abstract

The coronavirus disease 2019 pandemic has shown that a disposable surgical face mask is a good protective wall against infection due to its ability to prevent virus transmission from sick to healthy people. Nevertheless, these surgical masks are disposable, not ecofriendly, and are single-use items. The use and disposal of traditional masks lead to high secondary risks such as environmental pollution, pathogen transmission, overload demands, and user discomfort. Nanotechnology is one of the most investigated strategies to safely and economically reuse masks in the 21st century. These strategies are based on four key elements as follows: (1) super mechanical properties that give masks flexibility, durability, and good lifetime storage; (2) high thermal properties that give masks heat self-sterilization; (3) an electric charge controller that gives masks triboelectric (TE) filtration; and (4) response to the antimicrobial effect that stays in the mask before, during, and after safe use. These properties give new-generation masks the ability to remove the drawbacks of traditional surgical masks, such as microbial growth and low filtration efficiency. The graphene family has introduced the self-sterilization and TE effects of surgical masks. Silver nanoparticles have supported antimicrobial effects. Nanofiber membranes are fabricated to have a high surface area that improves the fiber diameter and porosity ratio. A traditional mask could only block a maximum of 50% of the exhaled viruses, but a nanofiber-based mask has been tested to intercept 90% to 99% of particle viruses while breathing during use. Complex nanocomposite materials have succeeded in collecting all these advantages.


---

## Body

## 1. Introduction

The standard precautions issued by the World Health Organization (WHO) state clearly that all health workers must consider that all substances from patients are sources of infections. Unfortunately, there are other sources of infections, such as air, nose, and mouth droplets, and even close contact. These are called “additional” (transmission-based) sources [1, 2]. Nonetheless, when people are in danger, they move involuntarily; they pull down the mask covering their face, so it only covers their mouth, leaving their nose exposed. Thus, the mask is an important piece of protection to be preserved in all circumstances. It is the simplest part of a comprehensive “Do it all!” [3]. The direct cause of infection is the lack of success in preventing viruses or bacteria from reaching the nose or mouth [4].The coronavirus disease 2019 (COVID-19) pandemic is considered a global health crisis and could be the greatest challenge that the world has faced since the Second World War. COVID-19 is transmitted by speaking, coughing, or sneezing through respiratory contact. It increased the global demand for personal protective equipment (PPE). The WHO recommended wearing all PPE, including masks, to limit the spread of the virus. Additionally, the main standard system used in health care is focused on PPE, such as masks [5, 6].Many of these studies focused on the reuse of masks and respirators by evaluating their performance and safety. These studies used many methods, such as ovens, autoclaves, thermal drying, and hydrogen peroxide plasma vapor [7]. Nevertheless, different organizations do not recommend reusing single-use surgical masks, and they prefer the extended use of single-use surgical masks over their reuse during situations of critical shortage [8].The extended use of single-use surgical masks produces millions of tons of plastic waste into the environment, subject to daily increase. Thus, this will create an overload of plastic waste with health hazards. This huge waste of plastic masks will increase both land and marine environmental pollution, as shown in Figure1. Biomask filters can be made from biodegradable fibers. Polysaccharides, such as coffee, hemp, bamboo, and sugar fibers, can be developed to prevent pollution caused by traditional masks; they are safe and can be recycled [9]. However, these biomasks must be antimicrobial.Figure 1
Different threats to life from the use of face masks (adapted with permission from Reference [9]).Bacteria and antibiotics have a history with each other. With the careful use of antibiotics, bacteria can be controlled. Unfortunately, the excessive use of antibiotics may lead to the emergence of more brutal bacteria called super bacteria that have harmful impacts on the environment [10]. In general, bacteria are always found in clinical and industrial environments associated with surfaces, unless in a strictly sterile environment [11]. Several studies have proven that bacteria can grow on face masks by breathing or even speaking while wearing the mask. Some studies have shown that the source of the infection is the surgeon’s body more than the hospital’s surroundings, where the inner layers of the mask are more infected than the outer layers, as shown in Figure 2 [12]. Therefore, the possibility of bacterial infection becomes very high. It has become very common on different occasions. People remove their masks and then put them back later, such as when eating and sweating; they create a suitable environment for these bacteria to grow [13].Figure 2
Comparison of bacterial contamination of masks: (a) used by the surgeon versus unused masks in the operating room and (b) inner layers versus outer layers (adapted with permission from Reference. [12]).
(a)(b)Traditional masks are made of several layers of cotton gauze, sometimes with an additional layer of waterproof material, held together by a metal frame. The main goal is to prevent respirable droplets from transmitting from and to the wearer. In contrast, surgical masks are made of a nonwoven fabric created using a melt-blowing process. They came into use in the 1960s and have largely replaced cloth face masks in developed countries [14]. Recently, nanotechnology has entered the manufacturing line of these surgical face masks due to their well-known characteristics. Accordingly, nanofibers are used in mask manufacturing to improve the efficiency of infection prevention.One of the most important application areas of nanotechnology is the biological and biomedical fields [15–18]. Nanotechnology shifts from information technology and electronics to biological and biomedical applications. Nanotechnology has appeared as a new technology in every branch of science. Without the advancement in nanotechnology, it would not be possible to overcome different challenging scientific dilemmas at the atomic level by building new materials with unique characteristics. These materials are used in biomedical applications, such as medicine and physiology, for biomaterials and devices that can be fabricated to interact with tissues and even cells at a molecular level with a high degree of interaction. Thus, this allows for a high integration degree between technology and biological systems which was not previously attainable [19–22].One of the advanced characteristics of nanoparticles (NPs) is their antimicrobial properties. The power of NPs as antimicrobial agents is widely studied and is being tested as an alternative method to overcome the challenges resulting from bacterial multidrug resistance. NPs have appeared globally as a novel direction to overcome bacterial multidrug resistance and antibiotic misuse. NPs can damage the microbial cell by direct contact with the bacterial cell membrane without the effort to penetrate the cell. In contrast, the toxicity of NPs is not fully explained and needs in-depth studies. The U.S. Food and Drug Administration has encouraged use of many NPs, such as silver NPs (AgNPs) and titanium dioxide NPs, for antibacterial skin products used commercially [23]. For example, AgNPs have antimicrobial activity and are used in dentistry, dermatology, and cardiology [24, 25]. Nanomaterials in the structure of new masks have been compared to traditional ones, showing that they improve the workers’ performance, the permeability efficiency of breathing, and comfort [26].


## 2. Fabrication Incorporating NPs

### 2.1. Inorganic NPs

Recently, researchers have improved a low-cost, reusable, and environmentally friendly material, such as a graphene cotton fabric (Figure3), and polymer modification depends on the good biological properties of the graphene family, mainly antibacterial activity [27].Figure 3
Schematic diagram of laser-induced graphene (adapted with permission from ref. [28]).Additionally, the antimicrobial activity of the graphene family is very efficient in relation to their ability to reduce environmental pollution. Moreover, they will be a solution to material shortages in supply. Thus, the graphene family consists of smart materials that are self-sterilized under sunlight radiation. The self-sterilization temperature of the graphene family occurs without requiring an oven and a sterilizing solution to disinfect severe acute respiratory syndrome or coronavirus [28–30].Some studies have successfully fabricated reusable surgical face masks based on graphene nanosheet-embedded carbon (GNEC) films, with high-density edges of standing structured graphene nanosheets [31, 32]. In addition, in the medical sector, workers cannot replace their masks in a short time. For this reason, the relative humidity (RH) inside the mask increases to a high-risk level (RH ≥ 75%). This may lead to lung inflammation [31]. Modified surgical face masks with GNEC exhibit high hydrophobic ability. The filtration efficiency of NEC is high, exhibiting a 100% performance of photosterilization of bacterial filtration, which can be heated above 100°C under solar illumination. This high performance may help combat COVID-19 outbreaks. Therefore, it reduces the economic consumption of masks [32]. In addition, modified surgical masks with graphene can be recycled in water desalination with high salt rejection performance [33]. The hydrophobic surfaces of surgical masks can be converted to superhydrophobic surfaces by coating them with an ultrathin graphene layer [34]. The antimicrobial property of graphene can be enhanced by adding NPs, such as AgNPs, copper oxide NPs [35], or anthraquinone-2-sodium sulfonate [10].Triboelectric (TE) face masks are designed to improve the efficiency and capture the nanofine particles called TE nanogenerators (TENG), supported by an electrocution layer (EL), which may deactivate microbes and viruses. This mask contains multilayer filters, and TE filtration depends on the inner three layers, and the outer one acts as an EL [36].In another TE filtration with graphene oxide (GO), a novel low-cost TENG ($1 per mask) is used as a commercial mask. It has an electrostatic rechargeability and high-efficiency filtration of >95% with a 20 kPa quality factor. This efficacy of this particle rejection size is 300 nm. This modified mask contains the following three layers similar to the traditional mask: “N95” nylon, modified polypropylene (PPY), fabric chemical modification of GO and polyvinylidene fluoride mixture (PPDFGO) composite, and nonwoven cotton . Compared to modified masks with conventional “N95,” the first one improves the TE charge and voltage of the PPY layer, as shown in Figure4 [37].Figure 4
(a) Potential of PPY, (b) potential of PPDFGO composite, (c) charge of PPY, and (d) charge of PPDFGO composite (adapted with permission from ref. [37]).
(a)(b)Silver inactivates bacteria by interacting with the thiol groups of bacterial proteins and enzymes [38]. The antimicrobial, wound-healing, and anti-inflammatory properties, and toxicity of cotton fabrics loaded with these three different concentrations of AgNP colloidal solution were evaluated [39]. For example, the cotton/AgNP composite was fabricated at low concentrations with 10–20 ppm AgNPs, as shown in Figure 5. The cotton/AgNP composite showed a high bacterial growth reduction. In 10–20 ppm AgNPs, the growth reduction values were 98.86% and 99.94%, respectively. Acrylic was used as a binder, which was very helpful in the cotton fabric permanence of AgNPs. Thus, it improved bacterial growth reduction [40].Figure 5
Scanning electron microscopy (SEM) image of (a) cotton and (b) cotton/AgNP composite (adapted with permission from ref. [40]).
(a)(b)The bacterial colony growth reduction was measured by the following equation [40]:(1)%R=A−BAwhere A is the colony number in a control sample and B is the colony number in a treatment cotton sample. Figure 6 compares bacterial reduction in a standard cotton sample and a cotton/AgNP sample at two concentrations [40].Figure 6
Bacterial reduction of (a) cotton sample, (b) 10 ppm cotton/AgNP sample, and (c) 20 ppm cotton/AgNP sample (adapted with permission from ref. [40]).
(a)(b)(c)Other inorganic NPs, such as copper NPs (CuNPs), showed excellent antimicrobial properties in comparing antibiotic molecules (tannic acid or bacitracin) and CuNPs. The antibacterial organic molecule essentially consisted of the damaged bacterial cell membrane (Bacillus subtilis). In contrast, CuNPs demonstrated bactericidal and bacteriostatic properties, including both nonmultidrug resistant bacteria (Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, and Staphylococcus aureus) and multidrug-resistant bacteria (methicillin-resistant S. aureus) [31]. Also, titanium dioxide generated hydroxyl radicals with highly reactive microbicides, such as CuNPs [38].


### 2.2. Organic NPs

The electrospinning technique of nano-based silk fibers was fabricated to improve air filter membranes [21]. Nanofiber membranes can efficiently filter the air, and many innovations have been introduced to design air filtering membranes using a nanotemplate. Several polymers were fabricated as film-based nano-face masks, such as PPY, polyurethane, polyacrylonitrile, polystyrene, polycarbonate, polyethylene, or polyester [41–46]. The nanofibers have high-efficiency filtration. They could remove particulate matter (PM) with a size of 0.310 μm, as shown in Figure 7. They also have additional advantages, such as a longer lifespan, high flexibility, and inert bioactivity [47]. Moreover, when the fiber diameter decreases to nanosize, the efficiency can increase due to the high surface area generated. Thus, the thickness of the membrane can be reduced to enhance low air resistance [48, 49].Figure 7
Interaction of PM with nanofibers (adapted with permission from ref. [45]).
(a)(b)(c)(d)(e)(f)(g)(h)Tebyetekerwa et al. [50] successfully proposed using durable yet reliable electrospun nonwoven filters with very small fibers with diameters of <100 nm. The filter can be processed by suitable disinfection methods and protocols to achieve reusability (increased usage time) without compromising the filtration efficiency. Beyond these, future face masks need to be antiviral and viricidal. The current electrospinning technology is mature, making the proposed strategy relatively low-cost with mass production capacity.Some researchers, such as Radacsi et al. [51], efficaciously reported the spontaneous formation of organic NPs on smooth nanofibers in a single-step electrospinning process as an inexpensive and scalable method for producing high surface area composites. Layers of nanofibers containing the proton-conducting electrolyte, cesium dihydrogen phosphate, were deposited uniformly over large area substrates from clear solutions of the electrolyte mixed with polymers.Many recent studies have shown that electrospun nanofibers, which have a high surface area per unit mass and are highly water resistant, can be successfully reused multiple times without losing any filtration efficiency, even after being dosed with ethanol. These results proved that the reusable nature of electrospun nanofibers compared to conventional melt-blown filters (Figure8) makes them superior in filtration [52].Figure 8
SEM images of (a) melt-blown fabrics, (b) nanofiber membrane, and (c) schematic for the comparison between melt-blown fiber and nanofiber diameters that are used to fabricate masks (adapted with permission from ref. [52]).
(a)(b)(c)When two or more nanomaterials come into a composite material, they will have super properties depending on their type and/or amount. In addition, it increases an active methodology to prevent the accumulation of living pathogens in the nanofiber structure [53]. Electrospinning is simple and low-cost to produce complex composite nanofibers with other NPs for different biomedical applications, such as the nontoxic profile of gold NPs [54].Aloufy and El-Messiry [55] successfully fabricated an effective filter layer of nanofibrous loaded with AgNPs to be combined later as one of the mask layers and then studied their efficiency to filter nanosize impurities and antimicrobial properties. It will help to calculate the disposable time recommended at hospitals and the nanosilver concentration. Figure 9 shows the comparison between bacterial growth on the nanofiber with and without AgNPs [55]. A polyvinylidene fluoride nanofiber with SiO2 NPs was fabricated to produce electric membrane air filtration with high filtration performance against different particle sizes [49].Figure 9
Effect of bacterial growth on the nanofiber with and without AgNPs (reproduced from ref. [55]).


## 2.1. Inorganic NPs

Recently, researchers have improved a low-cost, reusable, and environmentally friendly material, such as a graphene cotton fabric (Figure3), and polymer modification depends on the good biological properties of the graphene family, mainly antibacterial activity [27].Figure 3
Schematic diagram of laser-induced graphene (adapted with permission from ref. [28]).Additionally, the antimicrobial activity of the graphene family is very efficient in relation to their ability to reduce environmental pollution. Moreover, they will be a solution to material shortages in supply. Thus, the graphene family consists of smart materials that are self-sterilized under sunlight radiation. The self-sterilization temperature of the graphene family occurs without requiring an oven and a sterilizing solution to disinfect severe acute respiratory syndrome or coronavirus [28–30].Some studies have successfully fabricated reusable surgical face masks based on graphene nanosheet-embedded carbon (GNEC) films, with high-density edges of standing structured graphene nanosheets [31, 32]. In addition, in the medical sector, workers cannot replace their masks in a short time. For this reason, the relative humidity (RH) inside the mask increases to a high-risk level (RH ≥ 75%). This may lead to lung inflammation [31]. Modified surgical face masks with GNEC exhibit high hydrophobic ability. The filtration efficiency of NEC is high, exhibiting a 100% performance of photosterilization of bacterial filtration, which can be heated above 100°C under solar illumination. This high performance may help combat COVID-19 outbreaks. Therefore, it reduces the economic consumption of masks [32]. In addition, modified surgical masks with graphene can be recycled in water desalination with high salt rejection performance [33]. The hydrophobic surfaces of surgical masks can be converted to superhydrophobic surfaces by coating them with an ultrathin graphene layer [34]. The antimicrobial property of graphene can be enhanced by adding NPs, such as AgNPs, copper oxide NPs [35], or anthraquinone-2-sodium sulfonate [10].Triboelectric (TE) face masks are designed to improve the efficiency and capture the nanofine particles called TE nanogenerators (TENG), supported by an electrocution layer (EL), which may deactivate microbes and viruses. This mask contains multilayer filters, and TE filtration depends on the inner three layers, and the outer one acts as an EL [36].In another TE filtration with graphene oxide (GO), a novel low-cost TENG ($1 per mask) is used as a commercial mask. It has an electrostatic rechargeability and high-efficiency filtration of >95% with a 20 kPa quality factor. This efficacy of this particle rejection size is 300 nm. This modified mask contains the following three layers similar to the traditional mask: “N95” nylon, modified polypropylene (PPY), fabric chemical modification of GO and polyvinylidene fluoride mixture (PPDFGO) composite, and nonwoven cotton . Compared to modified masks with conventional “N95,” the first one improves the TE charge and voltage of the PPY layer, as shown in Figure4 [37].Figure 4
(a) Potential of PPY, (b) potential of PPDFGO composite, (c) charge of PPY, and (d) charge of PPDFGO composite (adapted with permission from ref. [37]).
(a)(b)Silver inactivates bacteria by interacting with the thiol groups of bacterial proteins and enzymes [38]. The antimicrobial, wound-healing, and anti-inflammatory properties, and toxicity of cotton fabrics loaded with these three different concentrations of AgNP colloidal solution were evaluated [39]. For example, the cotton/AgNP composite was fabricated at low concentrations with 10–20 ppm AgNPs, as shown in Figure 5. The cotton/AgNP composite showed a high bacterial growth reduction. In 10–20 ppm AgNPs, the growth reduction values were 98.86% and 99.94%, respectively. Acrylic was used as a binder, which was very helpful in the cotton fabric permanence of AgNPs. Thus, it improved bacterial growth reduction [40].Figure 5
Scanning electron microscopy (SEM) image of (a) cotton and (b) cotton/AgNP composite (adapted with permission from ref. [40]).
(a)(b)The bacterial colony growth reduction was measured by the following equation [40]:(1)%R=A−BAwhere A is the colony number in a control sample and B is the colony number in a treatment cotton sample. Figure 6 compares bacterial reduction in a standard cotton sample and a cotton/AgNP sample at two concentrations [40].Figure 6
Bacterial reduction of (a) cotton sample, (b) 10 ppm cotton/AgNP sample, and (c) 20 ppm cotton/AgNP sample (adapted with permission from ref. [40]).
(a)(b)(c)Other inorganic NPs, such as copper NPs (CuNPs), showed excellent antimicrobial properties in comparing antibiotic molecules (tannic acid or bacitracin) and CuNPs. The antibacterial organic molecule essentially consisted of the damaged bacterial cell membrane (Bacillus subtilis). In contrast, CuNPs demonstrated bactericidal and bacteriostatic properties, including both nonmultidrug resistant bacteria (Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, and Staphylococcus aureus) and multidrug-resistant bacteria (methicillin-resistant S. aureus) [31]. Also, titanium dioxide generated hydroxyl radicals with highly reactive microbicides, such as CuNPs [38].


## 2.2. Organic NPs

The electrospinning technique of nano-based silk fibers was fabricated to improve air filter membranes [21]. Nanofiber membranes can efficiently filter the air, and many innovations have been introduced to design air filtering membranes using a nanotemplate. Several polymers were fabricated as film-based nano-face masks, such as PPY, polyurethane, polyacrylonitrile, polystyrene, polycarbonate, polyethylene, or polyester [41–46]. The nanofibers have high-efficiency filtration. They could remove particulate matter (PM) with a size of 0.310 μm, as shown in Figure 7. They also have additional advantages, such as a longer lifespan, high flexibility, and inert bioactivity [47]. Moreover, when the fiber diameter decreases to nanosize, the efficiency can increase due to the high surface area generated. Thus, the thickness of the membrane can be reduced to enhance low air resistance [48, 49].Figure 7
Interaction of PM with nanofibers (adapted with permission from ref. [45]).
(a)(b)(c)(d)(e)(f)(g)(h)Tebyetekerwa et al. [50] successfully proposed using durable yet reliable electrospun nonwoven filters with very small fibers with diameters of <100 nm. The filter can be processed by suitable disinfection methods and protocols to achieve reusability (increased usage time) without compromising the filtration efficiency. Beyond these, future face masks need to be antiviral and viricidal. The current electrospinning technology is mature, making the proposed strategy relatively low-cost with mass production capacity.Some researchers, such as Radacsi et al. [51], efficaciously reported the spontaneous formation of organic NPs on smooth nanofibers in a single-step electrospinning process as an inexpensive and scalable method for producing high surface area composites. Layers of nanofibers containing the proton-conducting electrolyte, cesium dihydrogen phosphate, were deposited uniformly over large area substrates from clear solutions of the electrolyte mixed with polymers.Many recent studies have shown that electrospun nanofibers, which have a high surface area per unit mass and are highly water resistant, can be successfully reused multiple times without losing any filtration efficiency, even after being dosed with ethanol. These results proved that the reusable nature of electrospun nanofibers compared to conventional melt-blown filters (Figure8) makes them superior in filtration [52].Figure 8
SEM images of (a) melt-blown fabrics, (b) nanofiber membrane, and (c) schematic for the comparison between melt-blown fiber and nanofiber diameters that are used to fabricate masks (adapted with permission from ref. [52]).
(a)(b)(c)When two or more nanomaterials come into a composite material, they will have super properties depending on their type and/or amount. In addition, it increases an active methodology to prevent the accumulation of living pathogens in the nanofiber structure [53]. Electrospinning is simple and low-cost to produce complex composite nanofibers with other NPs for different biomedical applications, such as the nontoxic profile of gold NPs [54].Aloufy and El-Messiry [55] successfully fabricated an effective filter layer of nanofibrous loaded with AgNPs to be combined later as one of the mask layers and then studied their efficiency to filter nanosize impurities and antimicrobial properties. It will help to calculate the disposable time recommended at hospitals and the nanosilver concentration. Figure 9 shows the comparison between bacterial growth on the nanofiber with and without AgNPs [55]. A polyvinylidene fluoride nanofiber with SiO2 NPs was fabricated to produce electric membrane air filtration with high filtration performance against different particle sizes [49].Figure 9
Effect of bacterial growth on the nanofiber with and without AgNPs (reproduced from ref. [55]).


## 3. Evaluation and Discussion

Because of the COVID-19 pandemic, face masks have become a vital tool. Thus, humans can go about their normal day while dealing with COVID-19. Day after day, governments and the WHO recommend wearing a face mask. Many advanced materials have been developed based on nanotechnology. GO can be used as a coating to enhance the antimicrobial effects. These can help both the filters used and the fabric to prevent the transition of microbes from the mask to inhalation and hands. GO-based polymers can also increase the mechanical properties and ultraviolet (UV) resistance [56, 57]. The articles mentioned above shows that GO increases the hydrophobic properties of the inner and outer layers of face masks after reduction. Therefore, the correct term is reduced GO (rGO), which increases the hydrophobic property of textiles [58, 59]. In addition, the articles pointed out that the GO antimicrobial effect depends on the thermal property when exposed to sunlight. GO has many functional groups that interact with the bacterial membrane. It destroys microbes by damaging the cell membrane due to the chemical reaction of its functional groups. In contrast, rGO enhances mechanical stress and punctures the cell membrane by assisting in the inhibition of bacterial growth [60–62].Improvements in nanofiber materials have the potential to increase the efficiency of the filters. In addition, introducing nanotechnology in the manufacture of masks enhances respirators’ structural integrity [63]. Traditional face mask reuse methods have had limited success, failing to reach even 50% of fine particles [64]. UV treatments damage the structure of the mask, whereas chemical methods increase the penetration of the particles and reduce their efficiency. The use of steam shows some success but it is not practical [65]. Thus, conventional surgical masks suffer from many drawbacks, but modification with NPs could overcome these problems to produce super surgical masks. The following tables indicate surgical mask problems and solutions (Table 1) and a brief summary of the technologies used to improve face mask manufacturing (Table 2).Table 1
Shortcomings in traditional face masks and their solutions in nanofabrication.
Shortcomings in traditional masksRef.Solution using nanotechnologyRef.50% efficiency[66]99.9% efficiency[67]Bacterial contamination[68–74]Using antimicrobial material or self-sterilization[75–87]Degradation[88–94]Biodegradable materials[95–98]Storage and lifetime[99]Novel hydrophobic nanomaterial for long storage[100–104]Uncomfortable, which causes increases in pressure, temperature, and reduction of breath[105–113]Comfortability is controlled[114–118]Skin and ocular irritation; airflow increase evaporates the tear film[119–123]Dose level of ∼2000 mg/kg; no acute irritation for the eyes and skin[86, 87, 124]Uneconomic 129 billion face masks over the world every month, which means 3 million per minute[125](i) Reusable[126–128](ii) Biodegradable(iii) Withstand storage conditionsTable 2
A brief summary of technologies used to improve face mask manufacturing.
Technologies usedBrief descriptionRef.Nanomaterials based technologiesCopper dioxide, carbon, graphene, nanodiamonds, nanosilver, and titanium dioxide[4]Polyester blendNonwoven materials, with polypropylene, swiffer, and rayon[6]Filtering facepiece respiratorsVaporized hydrogen peroxide and ultraviolet germicidal irradiation[8]Natural plant fiberNatural plant fiber in the woven face mask technology and upcycling the mask waste[9]Modified graphene oxideGraphene oxide (GO) modified with anthraquinone-2-sodium sulfonate (AQS) through a noncovalent procedure[10]Silver nanoparticlesAg NP-based nanomaterials, biocompatible and antibacterial[22, 24, 25]BiocelluloseBiocellulose derived from cellulosic biomass[27]Laser induced graphene maskDual mode laser-induced mechanism[28]Electrospun nanofiber-based filtersSeveral flat, fine, fiber layers (µm in diameter) of nonwoven mats[30]Smart nanoassistedNanoclusters and plasmonic nanoparticles arranged in a hierarchical structure[31](GNEC) filmGraphene nanosheet-embedded carbon with high-density edges[32]Graphene oxide and polyvinylidene fluorideMixture containing paste using a simple solution casting method[37]Polymer nanofibers with cospinning abilityPolystyrene (PS), poly(methyl methacrylate), and polyvinylpyrrolidone (PVP) nanofibers[44]Vaporized hydrogen peroxideVaporized hydrogen peroxide (VHP), ultraviolet light (UV), and ethanol decontamination strategies[65]Thin copper@ZIF-8 core-shell nanowiresA novel material for treating blown polypropylene filtration media[129]Biobased cranberryNonwoven fabrics with antimicrobial coatings of cranberry[130]Solidified hand soapNonwoven fabric containing polymer filaments coated with solidified hand soap[131]Quaternary ammonium compoundsNonwoven face mask filter fabricated with a biofunctional coating of benzalkonium chloride[132]


## 4. Conclusions

It is fatal to deal with the COVID-19 pandemic using traditional masks. According to many studies, the time has come to use nanofabricated masks. Therefore, the key challenge is fabricating filtration masks with higher efficiency to decrease the penetration percentage in the nastiest conditions. The protection provided by standard surgical masks is superior to that provided by N95 respirators. However, according to several studies, surgical masks and N95 masks may not protect against NPs, such as viruses. In contrast, with the COVID-19 pandemic, the Centers for Disease Control and Prevention and the WHO recommended wearing face masks by the public. Traditional masks have many drawbacks. Therefore, their physical properties must be modified with nanomaterials to improve their performance. A nanofabricated mask can protect the user from incoming ultrafine viruses with a size of ∼50 nm. However, nanomaterials already available in face masks include graphene and different nanoadditives. These nanofabricated face masks are environmental friendly, antimicrobial, biodegradable, reusable, lightweight, comfortable, healthy, economical, and have a long storage time [46, 133–139].



---

*Source: 1497910-2022-09-16.xml*