Nanotechnology-enabled personal protection equipment

Summary

In the global fight against severe acute respiratory syndrome-CoV- 2 each individual is affected. The people are challenged to protect themselves and others. This combat is far more serious for the frontline and especially for health workers. In this regard, the role of personal protective equipment in this combat is essential. Nanoengineered solutions represent an innovative approach to medicine. Nanomaterials are reported to possess some unique characteristic as small size; improved solubility; surface adaptability; multifunctionality, antiviral/antibacterial activity, hydrophobicity, etc. All these open new opportunities for the development of innovative nano-enabled fabrics and textiles, providing increased personal protection. Furthermore, the application of nanotechnology-based surface coatings, drugs, and vaccines might be one of the possible solutions for limiting the global spread of severe viral diseases.

Key words/phrases: nano-enabled PPE, SARS-CoV-2, facemasks, nanomaterials, virus transmission pathways.

1. Introduction: SARS-Cov-2 – the infection agent of the novel disease COVID-19

In the winter of 2019, a new viral disease was discovered in Wuhan, China. The outbreak of this new and unknown disease forced the scientists to immediately clarify its epidemiology and etiology and to take action to fight it. The symptoms the new viral agent caused to infected humans have been described as fever, dry cough, malaise, rare cases of diarrhea, lymphopenia, and bilateral ground-glass opacity [9, 22]. These symptoms have been reported to be very similar to those caused by previously known pathogenic coronaviruses: SARS-CoV and MERS-CoV [58]. These two beta coronaviruses have been reported during the last 20 years as causative agents of two viral outbreaks: Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) – in 2002, in Guangdong Province, China [67] and the Middle East Respiratory Syndrome coronavirus (MERS-CoV) – in 2012, in the Middle East [64].

The studies of the new viral agent have started with the emergence of the first cases in China. The most important question at that time was how this new virus appeared? However, there have been suggested two opposite theories. Maybe the most common version for the origin of the new disease is that it has originated from the seafood and wet animal wholesale market in Wuhan, Hubei Province, China [45]. Other authors’ statements call into question the assumptions that the wholesale seafood and animal market is the only source of the newly found disease and bring light to the main pathway of disease transmission: human-to-human [9, 22].

The phylogenetic analyses of the novel coronavirus genomes and those of other beta coronavirus showed less than 90% identity, and according to that the new causative agent of viral pneumonia has been stated as a novel beta coronavirus and named 2019-nCoV. The disease caused by this viral agent was firstly named “novel coronavirus – infected pneumonia” (NCIP) [68]. The studies of the newly discovered coronavirus progressed along with its spread across the whole world, infecting millions of people. Based on the obtained information, the Coronavirus Study Group (CGS) of the International Committee on Virus Taxonomy (ICTV) announced, in early February 2020, the newly isolated infection agent as SARS-CoV-2 [19]. At the same time, the World Health Organization (WHO) named the disease caused by this CoV as COVID-19 (CO comes from “corona”, VI comes from “virus” and D comes from “disease”), and a month later, on 11th of March, 2020 – the outbreak of SARS-CoV-2 as a world pandemic [59].

2. The spread of SARS-CoV-2 and the need of personal protective equipment

2.1. Persistence in different environmental niches

The global and fast spread of the SARS-CoV-2 during the last 2 years led to an increase in the studies that aimed to characterize and determine the variety of environmental niches where the virus could present and persist. This knowledge is fundamental for realizing the ways of virus transmission on one hand and for inventing effective and reliable disease control strategies on the other hand.

The presence of COVID-19 infection agent or its genetic material in the water environment has been reported in a great number of studies, which has been stated as expected due to the unimpeded access of infected people to environmental water resources. Summaries of the data from a few studies have reported the presence of viral RNA/viral intact particles in different clinical samples such as urine, sputum, hospital stools, and others, although the nasopharyngeal samples of such patients have been negative, a few days after the infection. According to the research team, this finally might let to an increase of viral titters in hospital wastewater [1]. However, the presence of SARS-CoV-2 in wastewater samples has been demonstrated also in aerosols from wastewater in plant pumping stations during treatment activities [17, 65]. The persistence period of the infective agent in water and sewage has been reported to be 4.5 to 6 days depending on the environmental factors [18].

Other sources of viable virus particles have also been reported: air samples of different origins [28, 29], food samples [12], and tap water samples [7, 30]. The soil is perhaps the least studied environmental niche as a depot of SARS-CoV-2. However, the presence of viral RNA in soil samples, collected near hospitals, where patients infected with SARS-CoV-2 have been admitted for treatment, has been reported [66].

2.2. Presence and persistence of infectious viruses, including SARS-CoV-2, on different inanimate surfaces

The spread of SARS-CoV-2 in various environmental niches is a key prerequisite for the easy and rapid infection of many people simultaneously. The person-to-person transmission pathway is pointed as one of the most invasive [9].

However, the presumption of self-infecting after contact with virus-contaminated dry surfaces needs to be paid attention to as well. This alternative way of transmission has been proposed previously for other types of viruses, long before the COVID-19 pandemic [32]. In a survey published in 2000, Sizun et al. have compared the survival of two strains of human coronavirus (HCoV) on various surfaces and have found that they can persist on aluminium, latex gloves, and cotton gauze sponges for a few hours [48]. The potential sources of transmission of various nosocomial viruses (SARS, coxsackie, influenza, rhinoviruses, etc.) through contamination of different surfaces have also been summarized and it was concluded that they are capable to persist on them for a few days [27]. A similar investigation, that reveals the potential of avian metapneumovirus and avian influenza virus to survive on different solids, has been published, too. The results have shown that viable viral particles could be isolated up to the 9th day from nonporous surfaces, after contamination of the solid [53]. The potential of influenza virus (H1N1) to keep its viability on stainless steel solids has been studied and the results showed that it could be detected after 7 days [40]. Data about the stability of the coronaviruses, responsible for two viral outbreaks during the past two decades (SARS-Co-V and MERS-CoV), on different surfaces, has also been published. The results pointed out that the viruses could persist on solids like metals, glass, or plastic for 9 days [13, 25, 37].

The outbreak of SARS-CoV-2 forced the scientists to immediately study the potential of the virus to remain and persist on different surfaces that could serve as a source of infection. Such potential has been suggested due to the similarity of SARS-CoV-2 to the previously described pathogenic coronaviruses. Data about the virus stability on four different inanimate surfaces has been reported [55]. Thus, the ability of SARS-CoV-2 to survive on stainless steel, copper, plastic, and cardboard has been revealed. Another possible way of transmission of SARS-Co-V has been suggested by Ren and Tang – through coins and banknotes [44]. At that time, no experimental data concerning the potential of the virus to remain stable on banknotes paper had been published. Such hypotheses have been based on the results from studies of SARS-CoV-2 stability on printer and tissue paper [55]. In a recent study, data about banknotes as a reservoir of viable viral particles has been published. They showed that after 24 h at room temperature no viable virus particles have been detected on banknotes. However, greater stability of the virus on bank cards has been reported since viable viral particles have been detected after 48 h [35].

The long-term viability of the pathogenic viruses, including SARS-CoV-2, on different solids, bank cards, and other inert surfaces and their high levels of transmission by aerosols, person-to-person, and other known ways lead to two important issues: i) how an individual could protect oneself from these viruses and ii) how the mass spread of the viruses can be limited.

The application of different disinfecting agents and the use of personal protection equipment (PPE) are among the possible solutions.

2.3. Personal protective equipment’s – the WHO recommendations

Personal protective equipment is considered the last line of personal defense [15]. The basic concept of using PPE has two main aspects:

• to protect the individual from various risk factors during work;
• to protect other people from infections transmitted through air droplets.

In the light of the COVID-19 pandemic, the need for more knowledge on the ways to limit the spread of the viral agent and reduce the number of infected people, increased. As mentioned above, the causative agent of COVID-19 and other nosocomial viruses, including SARS-CoV and MERS-CoV, could be transmitted in different ways: person-to-person, through droplets of saliva (Fig. 1), through touching viral contaminated surfaces, etc.

Figure 1. Transmission of SARS-CoV 2 via saliva droplets

Due to this variety of transmission ways, WHO was forced to publish an Interim guidance – Rational use of personal protective equipment for coronavirus disease 2019 (COVID-19) on 27th February 2020, immediately after the emergence of the first cases of SARS-CoV-2 infected people. The role of this guidance was to give the community actual and specific recommendations for personal and social protection, namely the rational use of PPE. Among the specific recommendations in the guidance, were the following [60]:

• performing hand hygiene frequently with an alcohol-based hand rub if hands are not visibly dirty or with soap and water if hands are dirty;
• avoiding touching eyes, nose, and mouth;
• practicing respiratory hygiene by coughing or sneezing into a bent elbow or tissue and then immediately disposing of the tissue;
• wearing a medical mask if you have respiratory symptoms and performing hand hygiene after disposing of the mask;
• maintaining social distance (a minimum of 1 m) and staying away from those with respiratory symptoms.

According to the setting, personnel, and type of activity, the WHO has listed additional types of PPE, recommended for usage and application (Table 1) [60]:

Table 1. List of PPE recommended by WHO.

Setting	Target personnel or patients	Activity	Type of PPE
Healthcare facilities
Inpatient facilities
Patient room	Healthcare workers	Providing direct care to COVID-19 patients.	Medical mask Gown Gloves Eye protection (goggles or face shield).
		Aerosol-generating procedures performed on COVID-19 patients.	Respirator N95 or FFP2 standard, or equivalent. Gown Gloves Eye protection Apron
	Cleaners	Entering the room of COVID-19 patients.	Medical mask Gown Heavy duty gloves Eye protection (if risk of splash from organic material or chemicals). Boots or closed work shoes
	Visitors	Entering the room of a COVID-19 patient	Medical mask Gown Gloves
Other areas of patient transit (e.g., wards, corridors).	All staff, including healthcare workers.	Any activity that does not involve contact with COVID-19 patients.	No PPE required
Triage	Healthcare workers	Preliminary screening not involving direct contact	No PPE required
	Patients with respiratory symptoms.	Any	Maintain spatial distance of at least 1 m. Provide medical mask if tolerated by patient.
	Patients without respiratory symptoms.	Any	No PPE required
Laboratory	Lab technician	Manipulation of respiratory samples.	Medical mask Gown Gloves Eye protection (if risk of splash)
Administrative areas	All staff, including healthcare workers.	Administrative tasks that do not involve contact with COVID-19 patients.	No PPE required
Outpatient facilities
Consultation room	Healthcare workers	Physical examination of patient with respiratory symptoms.	Medical mask Gown Gloves Eye protection
	Healthcare workers	Physical examination of patients without respiratory symptoms.	PPE according to standard precautions and risk assessment.
	Patients with respiratory symptoms.	Any	Provide medical mask if tolerated.
	Patients without respiratory symptoms.	Any	No PPE required
	Cleaners	After and between consultations with patients with respiratory symptoms.	Medical mask Gown Heavy duty gloves Eye protection (if risk of splash from organic material or chemicals). Boots or closed work shoes
Waiting room	Patients with respiratory symptoms	Any	Provide medical mask if tolerated.
	Patients without respiratory symptoms	Any	No PPE required
Administrative areas	All staff, including healthcare workers.	Administrative tasks	No PPE required
Triage	Healthcare workers	Preliminary screening not involving direct contact	No PPE required
	Patients with respiratory symptoms.	Any	Provide medical mask if tolerated.
	Patients without respiratory symptoms	Any	No PPE required
Community
Home	Patients with respiratory symptoms	Any	Provide medical mask if tolerated, except when sleeping.
	Caregiver	Entering the patient’s room, but not providing direct care or assistance.	Medical mask
	Caregiver	Providing direct care or when handling stool, urine or waste from COVID-19 patient being cared for at home.	Gloves Medical mask Apron (if risk of splash)
	Healthcare workers	Providing direct care or assistance to a COVID-19 patient at home	Medical mask Gown Gloves Eye protection
Public areas (e.g., schools, shopping malls, train stations).	Individuals without respiratory symptoms	Any	No PPE required
Points of entry
Administrative areas	All staff	Any	No PPE required
Screening area	Staff	First screening (temperature measurement) not involving direct contact	No PPE required
	Staff	Second screening (i.e., interviewing passengers with fever for clinical symptoms suggestive of COVID-19 disease and travel history).	Medical mask Gloves
	Cleaners	Cleaning the area where passengers with fever are being screened.	Medical mask Gown Heavy duty gloves Eye protection (if risk of splash from organic material or chemicals). Boots or closed work shoes
Temporary isolation area	Staff	Entering the isolation area, but not providing direct assistance.	Maintain spatial distance of at least 1 m. Medical mask Gloves
	Staff, healthcare workers	Assisting passenger being transported to a healthcare facility	Medical mask Gown Gloves Eye protection
	Cleaners	Cleaning isolation area	Medical mask Gown Heavy duty gloves Eye protection (if risk of splash from organic material or chemicals). Boots or closed work shoes
Ambulance or transfer vehicle	Healthcare workers	Transporting suspected COVID-19 patients to the referral healthcare facility.	Medical mask Gowns Gloves Eye protection
	Driver	Involved only in driving the patient with suspected COVID-19 disease and the driver’s compartment is separated from the COVID-19 patient.	No PPE required
		Assisting with loading or unloading patient with suspected COVID-19 disease.	Eye protection
		No direct contact with patient with suspected COVID-19, but no separation between driver’s and patient’s compartments.	Medical mask
	Patient with suspected COVID-19 disease.	Transport to the referral healthcare facility.	Medical mask if tolerated
	Cleaners	Cleaning after and between transport of patients with suspected COVID-19 disease to the referral healthcare facility.	Medical mask Gown Heavy duty gloves Eye protection (if risk of splash from organic material or chemicals). Boots or closed work shoes
Special considerations for rapid response teams assisting with public health investigations
Community
Anywhere	Rapid response team investigators.	Interview suspected or confirmed COVID-19 patients or their contacts.	No PPE if done remotely (e.g., by telephone or video conference). Remote interview is the preferred method.
		In-person interview of suspected or confirmed COVID-19 patients without direct contact.	Medical mask
		In-person interview with asymptomatic contacts of COVID-19 patients.	No PPE required

Source: Interim guidance WHO, 2020 [60]

The way a conventional PPE kit looks is shown in Fig. 2. Each component of the kit has its specific function in the overall protection. The connections between the target protection area and a specific PPE component are as follows:

• Full body – coverall suit, aprons, and shoe leggings;
• Eyes – face shield, goggles;
• Nose and mouth – face mask;
• Hands – gloves;
• Head – hood cap.

The most important body areas, which must be completely protected are the eyes, nose, and mouth because these are the main entrance points for nosocomial and air-transmitted viruses entering the human body, including SARS-CoV-2.

Figure 2. The components of a standard PPE Kit

3. The contribution of nanotechnology in the global fight against new coronavirus disease

3.1. The broad concept of the nanotechnology

Viral infections and diseases are difficult to combat for various reasons, among which are the rapid viral mutations and the subsequent emergence of new variants and strains. The lack of reliable treatment challenged the scientists to develop new drugs that could be effective against a large number of viruses [24]. The limitation of this approach is that it takes a long period for the newly developed drugs to be declared effective and safe for use [10]. Thus, the attention has been focused on the prevention and invention of alternative approaches, designed to act at a different stage of the viral life cycle and consequently, efficiently impact the spread and development of viral infections [33]. In this regard, this is the exact place to emphasize the role of nanotechnology as a promising approach to combat viral diseases.

The basic concept of the science branch of Nanotechnology has been given by the Nobel laureate for physics, Richard P. Feynman in his lecture: ‘There’s plenty of room at the bottom’ in 1959 during a meeting of the American Physical Society [16]. In general, nanotechnology can be defined as the “design and application of several materials and devices where at least one dimension is less than 100 nanometres” [8]. Nanotechnology development is known to be in three basic directions [46]: nanomaterials, nanodevices, and nanosystems.

The direction related to the development and invention of nanomaterials is perhaps the most currently evolving. To completely understand the concept of nanotechnology and the related nanoparticles it is essential to clarify the meaning of the term “nano”. It comprises one billionth part (10-9) of a meter i.e., one meter has one billion nanometres. The size of nanoparticles (NPs) can be easily explained compared to different biomolecules and other bigger things like a tennis ball for example (Fig. 3). It is evident that the size of a cancer cell is 100 to 1000 – fold bigger than the size of a nanoparticle. The size of viral particles (including SARS-CoV-2) is approximately equal to those of nanoparticles.

Figure 3. Nanoparticles and their size

There are several reasons nanoparticles to be extensively studied. In this regard, some of their most important properties could be defined as the following [8]:

• small size;
• improved solubility;
• surface adaptability;

All aforementioned properties of the nanoparticles make them applicable in tissue-targeted treatment, personalized medicine, diagnosis, and prevention of viral and bacterial diseases [49]. In brief, the fields in which nanotechnology can be beneficial are far too diverse: medicine (drug development and application), ecology (water decontamination), technical applications (information and communication technologies), and so on [4].

3.2. Nanotechnology in the light of COVID-19

According to Campus et al. [8], the great potential of nanotechnology in the global fight against the SARS-CoV-2 could be realized through five main approaches (Fig. 4):

1. development of nano-enabled PPE;
2. development of nano-based anti-viral disinfectants and surface coatings, capable to catch and destroy the viral particles and thus stopping the spread;
3. the invention of nano-sensors with high specificity designed for quick viral identification and recognition of immunological response in the human body;
4. development of nano-based drugs for target therapy, direct in the affected lungs, for example. Nano-based drugs are considered to have increased effectiveness, decreased toxicity, and sustained release;
5. the invention of nano-based vaccines;

The urgent need for effective treatment of viral infections forced scientists to study different natural sources of active compounds such as plant extracts [5]. However, the efficiency of most of them has been considered weak due to their poor water solubility, low yield, difficult plant cultivation, etc. It is considered that to increase the therapeutic effect of the plant compounds they should be combined with nano-based materials [41].

The development of new generation vaccines, based on nanoparticles is another promising approach. These innovative vaccines have been considered to have some advantages over conventional ones, such as increased antigen delivery and stimulated immune response [2].

Figure 4. Nanotechnology application fields

Several studies have reported the application of nanoparticles in surface covering for the protection of viral and bacterial infections through a self-contaminating pathway [26, 36]. Such an innovative product has been developed by Sisson and Hackemeyer and had the potential to be applied on public surfaces with a high risk of viral contamination: elevator buttons, door handles, etc. The product named NanoTouch is a mineral nanocrystal-based coating activated by light (Fig. 5). The inventors have proven the effectiveness of the product against various viruses, including SARS-CoV-2 [51].

Figure 5. Self-cleaning nano-based surface coating, invented by NanoTouch/nanoSeptic

However, the concept of nano-based surface coating strategy in the fight against pathogenic microorganisms is closely related to the strategy of nano-based technologies for disinfection and sanitation. The information on such nano-based disinfectants, containing engineered water nanostructures, has been reported [56]. Its main advantage is that the applied disinfectant has significantly reduced the quantity of the pathogenic microorganisms after application. Another advantage was that the amount of the active compound required for effective disinfection was extremely low.

A commercially available nano-based disinfectant has been used for building disinfection in Milan during the outbreak of COVID-19. The formulation of the product has been based on Ag and TiO2 nanoparticles and it has been developed by the Italian nanotechnology company Nanotech Surface. The company’s manager claimed that the innovative formulation provides a “self-cleaning” ability for the treated surface for up to two years [52].

Like all new approaches in healthcare, treatment, and prevention, the nano-based products have to be declared safe and effective before their application at a community level. In this respect, the industrial nanobiotechnological companies must provide solid answers to some serious issues, concerning the safety and reliability of nanoproducts, their price, the legal regulation, etc. [8].

4. Nanotechnology-enabled PPE

The easy, fast, and global transmission of pathogenic coronavirus SARS-CoV-2 challenges each individual in his/her fight with the viral agent. In the situation of the global pandemic, two of the most important issues are: how the spread of the virus could be stopped or at least limited and how the people can protect themselves from the infection. The daily use of personal facemasks and gloves all over the world has become normal even in open spaces where the risk of infection is extremely high. However, as it is mentioned above (Table 1) the type of PPE, recommended by WHO could be different due to the current situation and the rate of the existing risk.

In this regard, the quality and effectiveness of the conventional PPE have become a key issue. For instance, many studies and reports demonstrate the negative effects of the long-term use of facemasks. Some of the most common complaints concern the increase in skin damage around the facemask area [14]. Additional restrictions on the prolonged wearing of a conventional facemask have been reported, such as unreliable protective ability and wearing discomfort [43]. It is reported that traditional face masks are produced from material that is ineffective in stopping the viral particles to reach the mouth and nose. The reason is locked in the size of the pores in the mask (10-30 µm) and the distance between the textile fibers that are too large to avoid the penetration of the 100 nm long viral particle. For example, conventional masks used by medical personnel (surgeons, nurses, healthcare staff, etc.) do not provide sufficient protection and the particles measuring up to 80 nm can pass through them. The global market spread face masks N95 and FFP2 protect against particles larger than 100 nm [21]. Nevertheless, some authors reported that if pore size and the distance between the structure fibers are reduced, the breathing will be critically impaired. The consequences of such a situation might be very serious, e.g. increase in body temperature and blood pressure [43].

The development and construction of innovative nano-based materials may be the key to overcoming all the aforementioned limitations in PPE effectiveness and safety. Several reports have shown that PPE, which contains nanomaterials (face masks, aprons, etc.) provides [50, 63]:

• better comfort;
• resistance to microorganisms (provide protection against particles smaller than 50 nm [11];
• increased safety to different chemical agents;
• hydrophobicity;
• no negative effects on materials;
• no negative effects on the breathing.

According to Campos et al., the application of nanomaterial in facemasks production offers two important advantages: i) the facemask acts simultaneously as a barrier and antimicrobial agent, resulting in blockage and destruction of the viral and bacterial pathogens; ii) diminishing the risk for self-infection of the wearer during the process of undressing [8]. Moreover, the viral particles are inactivated after contact with the nano-surface of the masks, i.e. the use of such PPE is environmentally safe.

Some of the patents for the manufacturing of PPE-containing nanomaterials are shown in Table 2.

Table 2. Patents for production of nano-enabled PPE.

PPE	Name of the product	Application of nanomaterial	Manufacturing company
Masks
1.	Surgical Masks-ESpin Technologies	Use of nanofibres for particles removal	ESpin Technologies, Inc.-USA
2.	Defenser Series-Respirator masks	The facemask has nanoparticles of silver and copper acting as a blend with antimicrobial activity	Nexera Medical-Canada
3.	The Guardian (valve)- reusable	The valve mask has nanoparticles of silver and copper acting as a blend with antimicrobial activity	Nexera Medical-Canada
4.	The Guardian masks- reusable	The valve mask has nanoparticles of silver and copper acting as a blend with antimicrobial activity	Nexera Medical-Canada
5.	MVX Nano Mask	A self-cleaning surgical mask containing titanium and silver zeolite nanoparticles	MVX Prime Ltd
Gloves
1.	Everyday Protect Gloves L	A product containing silver nanoparticles and the active compounds thiabendazole and zinc pyrithione	Mapa Spontex- United Kingdom
2.	PADYCARE®	Product coated with silver nanoparticles with antibacterial effect	TEXAMED® GmbH-Germany
3.	Chlorhexidine wash gloves	A product containing silver nanoparticles and 2% chlorhexidine; the antibacterial effects last many hours after use	GAMA HEALTHCARE LTD.

Source: Campos et al., 2020 [8]

Nanomaterials encompass each material that contains a “nano” structure: nanowhiskers, nanofibers, and nanoparticles.

4.1. Nanowhiskers

It is known that hydrophobicity is an important feature of the newly designed nano-materials. In the nano-constructed PPE, hydrophobicity has been achieved with the use of extremely tiny hydrocarbon fibers, known as nanowhiskers (Fig. 6). The nanowhiskers are responsible for increasing the surface tension of the textile material and thus, for decreasing its ability to adsorb droplets and other small molecules [8].

4.2. Nanofibers

A promising strategy in face mask manufacturing is the application of nanofibers. Such innovation has been patented by [11]. According to the author “nanofibers” can be different types: electrospun, protein, cellulose, bacterial, inorganic, hybrid, or any suitable combination thereof. The average diameter of the nanofibers can vary between 10 – 20 nm to 400 – 1500 nm. It is thought that the ability of the nanofibers to act as a barrier for small particles is due to two combined processes: i) catching the small particles by the nanofibers and ii) Brownian motion of the particles. Thus, the greater the nanofiber surface area is, the greater the capturing and protective ability of the nanofiber layer will be. The patent for a nanofiber-coated facemask of Conlon [11] is presented in Fig.7. The mask comprises three basic layers marked as 33, 36, and 39 between which the three basic layers are incorporated. Each basic layer has its own inner and outer surfaces.

Figure 6. Nanowhiskers attached to a textile fibre.

In the situation of a global pandemic, people are using PPE every day and sometimes during the whole day. Hence, ensuring physical comfort when wearing PPE is an essential issue. The long-term wearing of conventional facemasks led to discomfort and skin irritations due to the increase in temperature and moisture on the inner side of the mask. Also, these two conditions are prerequisites for increased microbial growth and hence for increased health risk. Frequently, the thermal discomfort is linked to the thickness of the masks. Yang et al. [62] have developed a face mask that ensures the wearer’s thermal comfort. The mask consists of a combination of nanofibers, nanoporous polyethylene, and a layer of silver. The authors have reported that such an innovative combination has an excellent cooling effect and protective abilities.

Figure 7. A facemask with nanofiber layers.

4.3. Nanoparticles

Another promising strategy in the manufacturing of facemasks with improved protective ability is the application of nanoparticles incorporated in the textile material. Various materials can serve as a matrix for the incorporation of nanoparticles: cotton, cellulose, polyamide, polyester, polyaramid, polyurethane, etc. [8].

Singh et al. have explored the potential of a nanocomposite, incorporated in the facemask’s material to determine its antiviral potential. The newly constructed nanomaterial consisted of carbon dots (C-dots) and poly(vinylidene fluoride) (PVDF) – C-dot-PVDF films [47]. The obtained results have shown that this nanocomposite assures hydrophobicity to the mask surface and thus, helps to reduce the moisture. The low moisture levels of the mask diminish the risk of its microbial contamination. Furthermore, the resulted nanoporous material did not affect the respiration through the mask and provided prevention against particles with a size of 100 nm and more (Fig. 8).

Figure 8. Facemask with incorporated C-dot-PVDF films.

It has been reported that carbon-based nanoparticles (for example Graphene and Graphene oxide) can bind to the viral particles and thus, destroy their outer structures [23]. The potential of such Graphene nanoparticles (G) and Graphene oxide nanoparticles (G) as a weapon against antimicrobial causative agents has been studied. Nanoparticles have been added to conventional materials used in PPE production (cotton and polyurethane). A solution containing live viral particles (SARS-CoV-2) has been filtered through the nano-coated material. The authors have found that after filtration the infection ability of the viral particles has been significantly or completely inhibited. Nano-based materials of such kind possess the potential to be implicated successfully in the combat against serious viral infections, including SARS-CoV-2. Furthermore, according to other authors, the incorporation of Graphene into textile materials can make them stronger, more conductive, and resistible to fire, abrasion, and UV light [6]. Various chemical substances, e.g., molybdenum sulfide, copper oxide, manganese dioxide, silicon carbide, etc., have been added to Graphene composites and their antimicrobial effect has been proven, too [42].

Another option is the metal NPs. It has been reported that the mechanism of their antiviral action consists of three basic stages: i) blocking the virus entry into the host cell; ii) stimulation of reactive oxygen species (ROS), radicals, and ions production that inactivates the basic functions of the viral particles, and iii) stimulation of the immune system of the macroorganism [42]. Silver and copper are known to have universal antimicrobial activity. Several studies, summarized by Campos et al., have shown the successful incorporation of these metals into various textile materials [8]. For instance, silver nanoparticles (composited in silica hybrid) have been shown to provide good antiviral activity against the influenza virus when added to filters [39]. Copper nanoparticles added to textile products have also been reported to affect the virus activity of various viruses, including SARS-CoV [69].

The advantages and the perspectives of the nano-engineered materials for the production of PPE are numerous. The summarized information concerning these advantages is shown in Fig. 9.

Figure 9. Main advantages of nano-based PPE.

5. Safety of nano-based products

The potential of nanotechnology is not limited to a single area. Here, the application of nanoparticles, nanofibers, and nanowhiskers in PPE production is discussed. However, nanotechnology possesses a broader potential. In the light of the COVID-19 outbreak and means for combating the disease, the main focuses and hopes are on the new scientific achievements, including in the field of nanotechnology. The development and areas of applications of nanotechnology in medicine (the so-called nanomedicine) can be classified into several main directions: diagnostic, treatment, and prevention of viral/bacterial diseases [8]. Besides the undoubted positives of nanotechnology, there are very important issues, concerning the safety application of nanoparticles, that must be considered. The limitations in using nano-based approaches in medicine could be due to some challenges, concerning their manufacturing, application, and biosafety release in the environment after use. The main aspects, deserving special attention could be classified as the following [8]:

• evaluation of safety application in/on the human body– it has been reported that some nanoparticles, e.g. Ag NPs incorporated in facemasks, can induce damage in the human body (in the lung, blood circulation, and heart) if they were inhaled [20]. Similar data have been reported for TiO2 NPs toxicity in humans, and the cancerogenic effect of the carbon nanotubes [31, 54]. Therefore, more in-depth tests in vivo must be performed to prove the safety of nanoparticles for the human body before their incorporation in PPE materials or drugs, that are in close contact with the outer/inner surface of the human body [8].
• evaluation of environmental safety– the effects of freely released nanoparticles in various environmental niches also must be carefully screened. For instance, silver and copper NPs have been reported to cause serious toxic damage to the marine ecosystem [3]. Comprehensive data on possible negative effects are currently insufficient and need to be improved [54].
• development of universal protocols for broad-spectrum characterization of nanomaterials– biological, physical, chemical, etc. – according to Palmieri et al., the responsibility for this has to be taken by the governments, and all manufacturing companies must follow the stated rules [38].
• adoption of a uniform definitionof the term “nanomaterials” [57];
• careful evaluation of the possibilitiesfor the manufacturing factories to meet the market needs [8].

The need for reliable solutions in human protection and disease treatment is essential. In this regard, nanotechnology might have a very bright future in various fields of medicine, including in PPE production.

---

Test LO 1.2

---

References

1. Adelodun B., Ajibade F.O., Tiamiyu A.G.O, Nwogwu N.A., Ibrahim R.G et al. (2021). Monitoring the presence and persistence of SARS-CoV-2 in water-food-environmental compartments: State of the knowledge and research needs. Environmental Research 200 111373; https://doi.org/10.1016/j.envres.2021.111373
2. Al-Halifa S., Gauthier L., Arpin D., Bourgault S. and Archambault D. (2019). Nanoparticle- based vaccines against respiratory viruses. Front Immunol.2019;10:22.
3. Baker T.J., Tyler C.R. and Galloway T.S. (2014). Impacts of metal and metal oxide nanoparticles on marine organisms, Environ. Pollut. 186 257–271.
4. Benelmekki, M. (2015). An introduction to nanoparticles and nanotechnology. Chapter 1. In: Designing Hybrid Nanoparticles. IOP Concise Physics. Morgan & Claypool Publishers
5. Ben-Shabat S., Yarmolinsky L., Porat D. and Dahan A. (2020). Antiviral effect of phytochemicals from medicinal plants: applications and drug delivery strategies. Drug Deliv. Transl. Res. 10:354–67.
6. Bhattacharjee S., Joshi R., Chughtai A.A. and Macintyre C.R. (2019). Graphene modified functional personal protective clothing, Adv. Mater. Interfaces 6, 1900622.
7. Bivins A., Greaves J., Fischer R., Yinda K.C., Ahmed,W., Kitajima M., Munster V.J. and Bibby K. (2020). Persistence of SARS-CoV-2 in water and wastewater. Environ. Sci. Technol. Lett. 7 (12), 937–942. https://doi.org/10.1021/acs.estlett.0c00730.
8. Campos E.V.R., Pereira A.E.S., de Oliveira J.L., Carvalho L.B., Guilger‑Casagrande M., de Lima R. and Fraceto L.F. (2020). How can nanotechnology help to combat COVID‑19? Opportunities and urgent need. Nanobiotechnol; 18:125, https://doi.org/10.1186/s12951-020-00685-4
9. Chan J.F-W, Yuan S., Kok K-H., et al. (2020). A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: a study of a family cluster. Lancet https://doi.org/10.1016/S0140-6736(20)30154-9.
10. Chen W-H, Strych U., Hotez P.J. and Bottazzi M.E. (2020). The SARS-CoV-2 vaccine pipeline: an overview. Curr Trop Med Rep. 7:61–4.
11. Conlon, M. (2014). A facemask having one or more nanofiber layers. 2014. https://paten ts.googl e.com/paten t/WO201 41430 39A1/en. Accessed 27 Apr 2020.
12. Dai M., Li H., Yan N., Huang J., Zhao L., Xu S., Wu J., Jiang S., Pan C. And Liao M. (2021). Long-term survival of SARS-CoV-2 on salmon as a source for international transmission. J. Infect. Dis. 223, 537–539. https://doi.org/10.1093/infdis/jiaa712.
13. Dowell S.F., Simmerman J.M., Erdman D.D., Wu J.S., Chaovavanich A., Javadi M., et al. (2004). Severe acute respiratory syndrome coronavirus on hospital surfaces. Clin Infect Dis; 39: 652e7.
14. Elston, D.M. (2020). Occupational skin disease among health care workers during the coronavirus (COVID-19) epidemic. J Am Acad Dermatol. 82: 1085–6.
15. Fact Sheet. Personal Protective Equipment for Engineered Nanoparticles. Sponsored by the AIHA® Nanotechnology Working Group, Date Reviewed: October 2018.
16. Feynman, R. P. (1960). There’s plenty of room at the bottom Engineering and Science 23 22–36
17. Gholipour S., Mohammadi F., Nikaeen M., Shamsizadeh Z., Khazeni A., Sahbaei Z.,Mousavi S.M., Ghobadian M. and Mirhendi H. (2021). COVID-19 infection risk from exposure to aerosols of wastewater treatment plants. Chemosphere 273, 129701. https://doi.org/10.1016/j.chemosphere.2021.129701.
18. Giacobbo A., Rodrigues M.A.S., Ferreira J.Z., Bernardes A.M. and de Pinho, M.N. (2021). A critical review on SARS-CoV-2 infectivity in water and wastewater. What do we know? Sci. Total Environ. 145721 https://doi.org/10.1016/j.scitotenv.2021.145721
19. Gorbalenya A.E., Baker S.C., Baric R.S., de Groot R.J., Drosten C., Gulyaeva A.A., Haagmans B.L., Lauber C., Leontovich A.M., Neuman B.W.; Penzar, D., Perlman S., Poon L.L.M., Samborskiy, D.V., Sidorov I.A., Sola I. and Ziebuhr J. (2020). Coronaviridae Study Group of the International Committee on Taxonomy of Viruses. The Species Severe Acute Respiratory Syndrome-Related Coronavirus: Classifying 2019-nCoV and naming it SARS-CoV-2. Nat. Microbiol. 5, 536−544.
20. Hadrup N., Sharma A.K., Loeschner K. and Jacobsen N.R. (2020). Pulmonary toxicity of silver vapours, nanoparticles and fine dusts: a review, Regul. Toxicol. Pharmacol. 115, 104690.
21. Herron J.B.T., Hay-David A.G.C., Gilliam A.D. and Brennan P.A. (2020). Personal protective equipment and Covid 19—a risk to healthcare staff? Br J Oral Maxillofac Surg. 58(5):500–2.
22. Huang C., Wang Y., Li X., Ren L., Zhao J., Hu Y., Zhang L., et al. (2020). Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet 2020; 395: 497–506, https://doi.org/10.1016/S0140-6736(20)30183-5.
23. Innocenzi P. and Stagi L. (2020). Carbon-based antiviral nanomaterials: graphene, C-dots, and fullerenes. A perspective. Chem Sci. 2020;11(26):6606–22.
24. Jackman J.A., Lee J. and Cho N-J. (2016). Nanomedicine for infectious disease applications: innovation towards broad-spectrum treatment of viral infections. Small, 12:1133–9.
25. Kampf G., Todt D., Pfaender S. and Steinmann E. (2020). Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents. J. Hosp. Infect. 104, 246–251. https://doi.org/10.1016/j.jhin.2020.01.022.
26. Karunanayake L.I., Waniganayake Y.C., Gunawardena K.D.N., Padmaraja S.A.D., Peter D., Jayasekera R., et al. (2019). Use of silicon nanoparticle surface coating in infection control: experience in a tropical healthcare setting. Infect Dis Health. 24:201–7.
27. Kramer A., Schwebke I. and Kampf G., (2006). How long do nosocomial pathogens persist on inanimate surfaces? A systematic review. BMC Infect. Dis. 6, 130. https://doi.org/ 10.1186/1471-2334-6-130.
28. Lednicky J.A., Lauzardo M., Alam M.M., Elbadry M.A., Stephenson C.J., Gibson J.C. and Morris J.G. (2021). Isolation of SARS-CoV-2 from the air in a car driven by a COVID patient with mild illness. Int. J. Infect. Dis. 103108. https://doi.org/10.1016/j.ijid.2021.04.063.
29. Lednicky J.A., Lauzard M., Fan Z.H., Jutla A., Tilly T.B., Gangwar M., Usmani M., et al. (2020). Viable SARS-CoV-2 in the air of a hospital room with COVID-19 patients. Int. J. Infect. Dis. 100, 476–482. https://doi.org/10.1016/j.ijid.2020.09.025
30. Lee Y.J., Kim J.H., Choi B.S., Choi J.H. and Jeong Y.I. (2020). Characterization of severe acute respiratory syndrome coronavirus 2 stability in multiple water matrices. J. Kor. Med. Sci. 35, 1–5. https://doi.org/10.3346/jkms.2020.35.e330.
31. Luo Z., Li Z., Xie Z., Sokolova I.M, Song L., Peijnenburg W.J.G.M., Hu M. and Wang Y. (2020). Rethinking nano‐TiO2 safety: overview of toxic effects in humans and aquatic animals, Small 2002019.
32. Mahl M.C. and Sadler C. (1975). Virus survival on inanimate surfaces. Can. J. Microbiol. 21, 819–823. https://doi.org/10.1139/m75-121.
33. Mohammadi P.P, Fakhri S., Asgary S., Farzaei M.H. and Echeverrнa J. (2019). The signaling pathways, and therapeutic targets of antiviral agents: focusing on the antiviral approaches and clinical perspectives of anthocyanins in the management of viral diseases. Front Pharmacol. 10:1207.
34. Mohapatra H.S., Chatterjee A. and Maity S. (2013). Nanotechnology in Fibres and Textiles. International Journal of Recent Technology and Engineering (IJRTE) ISSN: 2, 5:2277-3878.
35. Newey C.R., Olausson A.T., Applegate A., Reid A-A., Robison R.A. and Grose J.H. (2022). Presence and stability of SARS-CoV-2 on environmental currency and money cards in Utah reveals a lack of live virus. PLoS ONE 17(1): e0263025. https://doi.org/10.1371/journal.pone.0263025.
36. Orti-Lucas R.M. and Muсoz-Miguel J. (2017). Effectiveness of surface coatings containing silver ions in bacterial decontamination in a recovery unit. Antimicrob Resist Infect Control. 6:61.
37. Otter J.A., Donskey C., Yezli S., Douthwaite S., Goldenberg S.D. and Weber D.J. (2016). Transmission of SARS and MERS coronaviruses and influenza virus in healthcare settings: the possible role of dry surface contamination. J Hosp Infect. 92:235e50.
38. Palmieri V., De Maiod F., De Spiritob M. and Papib M. (2021). Face masks and nanotechnology: Keep the blue side up. Elsevier, Nano Today 37 (2021) 101077. https://doi.org/10.1016/j.nantod.2021.101077
39. Park S., Ko Y-S., Lee S.J., Lee C., Woo K. and Ko G. (2018). Inactivation of influenza A virus via exposure to silver nanoparticle-decorated silica hybrid composites. Environ Sci Pollut Res. 25: 27021–30.
40. Perry K.A., Coulliette A.D., Rose L.J., Shams A.M., Edwards J.R. and Noble-Wang J.A. (2016). Persistence of Influenza A (H1N1) virus on stainless steel surfaces. Appl. Environ. Microbiol. 82, 3239–3245. https://doi.org/10.1128/AEM.04046-15.
41. Praditya D., Kirchhoff L., Brьning J., Rachmawati H., Steinmann J. and Steinmann E. (2019). Anti-infective properties of the golden spice curcumin. FrontMicrobiol. 10: 912.
42. Ray S.S. and Bandyopadhyay J. (2021). Nanotechnology-enabled biomedical engineering: Current trends, future scopes, and perspectives. Nanotechnology Reviews 2021; 10: 728–743 https://doi.org/10.1515/ntrev-2021-0052
43. Ren G., Oxford P.J.S., Reip P.W., Lambkin-Williams R. and Mann A. (2020). Anti-viral formulations nanomaterials and nanoparticles. 2013. https ://patents.googl e.com/paten t/US201 30091 611/de. Accessed 27 Apr 2020.
44. Ren T. and Tang Y. (2020). Accelerate the promotion of mobile payments during the COVID- 19 epidemic. Innovation 1, 100039. https://doi.org/10.1016/j.xinn.2020.100039.
45. Report of clustering pneumonia of unknown etiology in Wuhan City. Wuhan Municipal Health Commission, 2019. (http://wjw .wuhan .gov .cn/ front/ web/ showDetail/ 2019123108989).
46. Salata, O.V. (2004). Applications of nanoparticles in biology and medicine.Journal of Nanobiotechnology, 2:3 http://www.jnanobiotechnology.com/content/2/1/3
47. Singh S., Shauloff N., Sharma C.P., Shimoni R., Arnusch C.J. and Jelinek R. (2021). Carbon dot-polymer nanoporous membrane for recyclable sunlight-sterilized facemasks. J Colloid Interface Sci. 592(5):342–8.
48. Sizun J., Yu M.W. and Talbot P.J. (2000). Survival of human coronaviruses 229E and OC43 in suspension and after drying onsurfaces: a possible source ofhospital-acquired infections. J. Hosp. Infect. 46, 55–60. https://doi.org/10.1053/jhin.2000.0795.
49. Soares S., Sousa J., Pais A. and Vitorino C. (2018). Nanomedicine: principles, properties, and regulatory issues. Front Chem. 6:360.
50. Spagnol C., Fragal E.H., Pereira A.G.B., Nakamura C.V., Muniz E.C., Follmann H.D.M., et al. (2018). Cellulose nanowhiskers decorated with silver nanoparticles as an additive to antibacterial polymers membranes fabricated by electrospinning. J Colloid Interface Sci. 531: 705–15.
51. (2020). Mineral nanocrystal-based coating activated by light kills coronavirus STATNANO. 2020. https://nanotouch.com/; Accessed 7 Aug 2020.
52. (2020). Coronavirus: nanotech surface sanitizes Milan with nanomaterials remaining self-sterilized for years | Coronavirus: Nanotech Surface Sanitizes Milan with Nanomaterials Remaining Self-sterilized for Years | STATNANOAccessed 28 Apr 2020.
53. Tiwari A., Patnayak D.P., Chander Y., Parsad M. and Goyal S.M. (2006). Survival of two avian respiratory viruses on porous and nonporous surfaces. Avian Dis. 50, 284–287. https://doi.org/10.1637/7453-101205R.1.
54. Valdiglesias V. and Laffon B. (2020). The impact of nanotechnology in the current universal COVID-19 crisis. Let’s not forget nanosafety!, Nanotoxicology 14 1013–1016.
55. van Doremalen N., Bushmaker T., Morris D.H., Holbrook M.G., Gamble A., Williamson B.N., Tamin A., et al. (2020). Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. N. Engl. J. Med. 382, 1564–1567. https://doi. org/10.1056/NEJMc2004973.
56. Vaze N., Pyrgiotakis G., McDevitt J., Mena L., Melo A., Bedugnis A., et al. (2019). Inactivation of common hospital acquired pathogens on surfaces and in air utilizing engineered water nanostructures (EWNS) based nanosanitizers. Nanomed Nanotechnol Biol Med. 18:234–42.
57. Wacker M.G., Proykova A. and Santos G.M.L. (2016). Dealing with nanosafety around the globe-regulation vs. innovation. Int J Pharm. 509:95–106.
58. Wang C., Horby P.W., Hayden F.G. and Gao G.F. (2020).A novel coronavirus outbreak of global health concern. The Lancet, Vol 395, ISSUE 10223, P470-473, DOI: https://doi.org/10.1016/S0140-6736(20)30185-9
59. World Health Organization. Situation Report – 51; https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200311-sitrep-51-covid-19.pdf?sfvrsn=1ba62e57_10.
60. World Health Organization. Rational use of personal protective equipment for coronavirus disease 2019 (COVID-19). Interim guidance. 27 February 2020.
61. Xu R., Cui B., Duan X., Zhang P., Zhou X. and Yuan Q. (2020). Saliva: potential diagnostic value and transmission of 2019-nCoV. International Journal of Oral Science 12:11; https://doi.org/10.1038/s41368-020-0080-z
62. Yang A.L., Zhang C.R, Wang J., Hsu P.C, Wang H., Zhou G., Xu J., Cui Y. (2017). Thermal management in nanofiber-based face mask, Nano Lett. 17 3506–3510.
63. Yetisen A.K., Qu H., Manbachi A., Butt H., Dokmeci M.R., Hinestroza J.P., et al. (2016). Nanotechnology in textiles. ACS Nano. 10: 3042–68.
64. Zaki A.M., van Boheemen S., Bestebroer T.M., Osterhaus A.D. and Fouchier R.A. (2012). Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. N Engl J Med .367:1814-20.
65. Zaneti R.N., Girardi V., Spilki F.R., Mena K., Westphalen A.P.C., da Costa Colares E. R., Pozzebon A.G. and Etchepare R.G. (2021). Quantitative microbial risk assessment of SARS-CoV-2 for workers in wastewater treatment plants. Sci. Total Environ. 754, 142163. https://doi.org/10.1016/j.scitotenv.2020.142163.
66. Zhang D., Yang Y., Huang X., Jiang J., Li M., Zhang X., Ling H., et al. (2020). SARS-CoV-2 spillover into hospital outdoor environments. medRxiv 86, 05.12.20097105.
67. Zhong N.S., Zheng B.J., Li Y.M., et al. (2003). Epidemiology and cause of severe acute respiratory syndrome (SARS) in Guangdong, People’s Republic of China, in February, 2003. Lancet 362: 1353–58.
68. Zhu N., Zhang D., Wang W. et al. (2020). A novel coronavirus from patients with pneumonia in China, 2019. N. Engl. J. Med. 382(8), 727–733 (2020).
69. ФУДЖИMOPИ И., ДЖИКИXИPA И., CATO T., ФУКУИ Й., HAКAЯMA Ц. (2020). Virus inactivating cloth. 2015. https ://paten ts.googl e.com/paten t/RU255 0922C 2/en. Accessed 27 Apr 2020.