Biodegradable and multifunctional surgical face masks: A brief review on demands during COVID-19 pandemic, recent developments, and future perspectives

Enhanced and copper concentration dependent virucidal effect against SARS-CoV-2 of electrospun poly(vinylidene difluoride) filter materials

Virucidal filter materials were prepared by electrospinning a solution of 28 wt % poly(vinylidene difluoride) in N,N-dimethylacetamide without and with the addition of 0.25 wt %, 0.75 wt %, 2.0 wt %, or 3.5 wt % Cu(NO3)2 · 2.5H2O as virucidal agent. The fabricated materials had a uniform and defect free fibrous structure and even distribution of copper nanoclusters. X-ray diffraction analysis showed that during the electrospinning process, Cu(NO3)2 · 2.5H2O changed into Cu2(NO3)(OH)3. Electrospun filter materials obtained by electrospinning were essentially macroporous. Smaller pores of copper nanoclusters containing materials resulted in higher particle filtration than those without copper nanoclusters. Electrospun filter material fabricated with the addition of 2.0 wt % and 3.5 wt % of Cu(NO3)2 · 2.5H2O in a spinning solution showed significant virucidal activity, and there was 2.5 ± 0.35 and 3.2 ± 0.30 logarithmic reduction in the concentration of infectious SARS-CoV-2 within 12 h, respectively. The electrospun filter materials were stable as they retained virucidal activity for three months.

Preparation of an innovative series of respiratory nano-filters using polystyrene fibrous films containing KCC-1 dendrimer and ZnO nanostructures for environmental assessment of SO2, NO2 and CO2

Air pollution has become a major challenge that threatens human health. The use of respiratory filters is one of the proposed solutions. In this study, using polystyrene (PS) fibers and various nanomaterials, improved respiratory filters were fabricated to remove air pollutants. In this context, ZnO nanoparticles (ZnO NPs) integrated into dendritic structures of KCC-1 silica were used to improve the filters' ability to absorb pollutants. For the first time, the removal of gasses by modified filters with a novel polymeric nanocomposite (PS/ZnO-KCC-1) stabilized on the surface of respiratory filters was investigated. Moreover, two different methods including stabilized- and solution-based techniques were used to prepare the filters with different amounts of ZnO NPs and their efficiency was evaluated. All synthesized nanocomposites and developed filters were characterized by FT-IR, FESEM, TGA and XRD methods. The successful stabilization of nanostructures on the fibers was proved and the performance of the fibers was investigated with some tests, such as pressure drop and removal of suspended particles and CO2 (89%), NO2 (86%), and SO2 (83%) gases. PS/KCC-1-ZnO (5%) has better performance than other prepared fibers. The results showed that the removal of suspended particles in the filter containing ZnO and KCC-1 (M5) nanostructures was improved by 18% compared to the filter consisting of polystyrene fibers. The pressure drop increased with the addition of nanostructures and reached 180 Pa in the M5 filter. The filter containing ZnO NPs showed antibacterial activity against Staphylococcus (S.) aureus and Escherichia (E.) coli as Gram-positive and Gram-negative model bacteria using the Agar disk-diffusion method. Based on the results, the use of improved respiratory filters is recommended as an effective solution for combating air pollution and protecting human health.

Identification of new pharmacophore against SARS-CoV-2 spike protein by multi-fold computational and biochemical techniques

COVID-19 appeared as a highly contagious disease after its outbreak in December 2019 by the virus, named SARS-CoV-2. The threat, which originated in Wuhan, China, swiftly became an international emergency. Among different genomic products, spike protein of virus plays a crucial role in the initiation of the infection by binding to the human lung cells, therefore, SARS-CoV-2's spike protein is a promising therapeutic target. Using a combination of a structure-based virtual screening and biochemical assay, this study seeks possible therapeutic candidates that specifically target the viral spike protein. A database of ~ 850 naturally derived compounds was screened against SARS-CoV-2 spike protein to find natural inhibitors. Using virtual screening and inhibitory experiments, we identified acetyl 11-keto-boswellic acid (AKBA) as a promising molecule for spike protein, which encouraged us to scan the rest of AKBA derivatives in our in-house database via 2D-similarity searching. Later 19 compounds with > 85% similarity with AKBA were selected and docked with receptor binding domain (RBD) of spike protein. Those hits declared significant interactions at the RBD interface, best possess and excellent drug-likeness and pharmacokinetics properties with high gastrointestinal absorption (GIA) without toxicity and allergenicity. Our in-silico observations were eventually validated by in vitro bioassay, interestingly, 10 compounds (A3, A4, C3, C6A, C6B, C6C, C6E, C6H, C6I, and C6J) displayed significant inhibitory ability with good percent inhibition (range: > 72-90). The compounds C3 (90.00%), C6E (91.00%), C6C (87.20%), and C6D (86.23%) demonstrated excellent anti-SARS CoV-2 spike protein activities. The docking interaction of high percent inhibition of inhibitor compounds C3 and C6E was confirmed by MD Simulation. In the molecular dynamics simulation, we observed the stable dynamics of spike protein inhibitor complexes and the influence of inhibitor binding on the protein's conformational arrangements. The binding free energy ΔGTOTAL of C3 (-38.0 ± 0.08 kcal/mol) and C6E (-41.98 ± 0.08 kcal/mol) respectively indicate a strong binding affinity to Spike protein active pocket. These findings demonstrate that these molecules particularly inhibit the function of spike protein and, therefore have the potential to be evaluated as drug candidates against SARS-CoV-2.

Influence of Electrospinning Parameters on the Morphology of Electrospun Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Fibrous Membranes and Their Application as Potential Air Filtration Materials

A large number of non-degradable materials have severely damaged the ecological environment. Now, people are increasingly pursuing the use of environmentally friendly materials to replace traditional chemical materials. Polyhydroxyalkonates (PHAs) are receiving increasing attention because of the unique biodegradability and biocompatibility they offer. However, the applications of PHAs are still limited due to high production costs and insufficient study. This project examines the optimal electrospinning parameters for the production of PHA-based fibrous membranes for air filtration. A common biodegradable polyester, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), was electrospun into a nanofibrous membrane with a well-controlled surface microstructure. In order to produce smooth, bead-free fibers with micron-scale diameters, the effect of the process parameters (applied electric field, solution flow rate, inner diameter of hollow needle, and polymer concentration) on the electrospun fiber microstructure was optimized. The well-defined fibrous structure was optimized at an applied electric field of 20 kV, flow rate of 0.5 mL/h, solution concentration of 12 wt.%, and needle inner diameter of 0.21 mm. The morphology of the electrospun PHBV fibrous membrane was observed by scanning electron microscopy (SEM). Fourier transform infrared (FTIR) and Raman spectroscopy were used to explore the chemical signatures and phases of the electrospun PHBV nanofiber. The ball burst strength (BBS) was measured to assess the mechanical strength of the membrane. The small pore size of the nanofiber membranes ensured they had good application prospects in the field of air filtration. The particle filtration efficiency (PFE) of the optimized electrospun PHBV fibrous membrane was above 98% at standard atmospheric pressure.

An insight into the benefits of substituting polypropylene with biodegradable polylactic acid face masks for combating environmental emissions

Mask waste can affect the natural environment and human health. In this study, the life cycle assessment (LCA) of two types of face masks (Polylactic acid (PLA) and Polypropylene (PP)) was first performed to evaluate the environmental impacts from production to end-of-life, and then, greenhouse gas (GHG) emissions were estimated for each life stage. The GHG emissions for one functional unit of PP and PLA face masks were estimated to be 6.27E+07 and 5.06E+07 kg CO2 eq, respectively. Explicitly, PLA mask production emissions are 37 % lower as compared to those for PP masks. Packaging has been recognized as a major GHG source throughout the product's life cycle. This study may provide a new insight into the environmental benefits of reducing GHG emissions within PLA face mask life cycles. Biodegradable and environmentally friendly materials can be used in the manufacturing and packaging of face masks.

Preparation and Application of High-Efficiency, Antibacterial, and Antiviral PET-PTHP Fibers

Transmission through the respiratory tract is one of the most important ways for bacteria and viruses to infect the human body; the use of high-performance antibacterial and antiviral protective equipment is the most effective way to prevent the spread of respiratory diseases. However, at present, most personal protective equipment lacks the ability to kill pathogens. In this paper, a kind of polytetrahydropyrimidine-polyethylene terephthalate functional fiber (PET-PTHP fibers) with highly sustained antibacterial and antiviral properties was prepared. The inactivation rate of the fibers against Staphylococcus aureus and Escherichia coli was as high as 99.99%, and the antibacterial time was more than 72 h. The fibers have an obvious destructive effect on lentiviruses and can reduce the infection rate of lentiviruses in BxPC-3 cells from 25.4 to 9.7%. The cytotoxicity test, cell live/dead staining test, and cell proliferation test all confirmed that PET-PTHP fibers have no obvious cytotoxicity and good cytocompatibility. By applying the functional fibers to the inner layer of the masks, a new type of mask with adsorption, filtration, and killing properties against pathogens was prepared. The filtration efficiency of the new masks was 99.3%, and the pressure drop was 104 Pa. The new masks have excellent air permeability and filtration effect, meet the practical application conditions, and are of grade A; therefore, these masks provide medical protection as well as kill pathogens at the same time, further reducing the risk of human infection.

Post-Pandemic: Investigation of the Degradation of Various Commercial Masks in the Marine Environment

During COVID-19, personal protective equipment such as face masks was in urgent demand in the daily life. As the pandemic may have withdrawn from public attention, the disposal of face masks is a significant issue, especially plastic pollution. To address the degradation of the polymers in the marine environment, seven commercial masks were investigated via artificial weathering procedures in substitute ocean water. A suite of structural and chemical characterization techniques was employed, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), and contact angle goniometry, to probe the treatment impact on commercially available N95, surgical, polyurethane, polyester, nylon, silk, and cotton masks. This work provides insights into the comprehensive analysis of material degradation in nature and raises public awareness of environmental issues post-pandemic.

Advancement of Nonwoven Fabrics in Personal Protective Equipment

While nonwoven fabrics have existed for several decades, their usage in personal protective equipment (PPE) has been met with a rapid surge of demands, in part due to the recent COVID-19 pandemic. This review aims to critically examine the current state of nonwoven PPE fabrics by exploring (i) the material constituents and processing steps to produce fibers and bond them, and (ii) how each fabric layer is integrated into a textile, and how the assembled textiles are used as PPE. Firstly, filament fibers are manufactured via dry, wet, and polymer-laid fiber spinning methods. Then the fibers are bonded via chemical, thermal, and mechanical means. Emergent nonwoven processes such as electrospinning and centrifugal spinning to produce unique ultrafine nanofibers are discussed. Nonwoven PPE applications are categorized as filters, medical usage, and protective garments. The role of each nonwoven layer, its role, and textile integration are discussed. Finally, the challenges stemming from the single-use nature of nonwoven PPEs are discussed, especially in the context of growing concerns over sustainability. Then, emerging solutions to address sustainability issues with material and processing innovations are explored.

Design and fabrication of a biodegradable face shield by using cleaner technologies for the protection of direct splash and airborne pathogens during the COVID-19 pandemic

Due to global supply chain disruptions and high demand for personal protective equipment (PPE), the rapidly expanding COVID-19 crisis left millions of front-line fighters unprotected. The disposal of PPE in the environment caused significant environmental pollution. Hence, indigenous initiatives have been taken to fabricate antiviral and biodegradable face shields with the help of neoteric and cleaner technologies. This paper describes a novel endeavor to design, manufacture, and performance analysis of a face shield made by plastic injection molding and LASER Cutting. Because of the requirement of permanent wear, the face shield's ergonomic design is considered low weight and easy head fixation, alongside high production ability. Here, face shield frames are made with lightweight, biodegradable plastic called Poly Lactic Acid (PLA), whereas an optical grade PLA sheet is used as the visor for better clarity. Visors PLA Sheet is coated with Nano-Silver disinfectant spray to incorporate antiviral properties to the Faceshield. Partially circumferential adjustable elastic straps are used for comfortable head fixation. To evaluate the product, clinical fit tests along with statistical survey were conducted, and the feedback from the end-users on comfort (41% Excellent, 30% Good, 26% Average and 3% Poor), clear view (33% Excellent, 38% Good, 24% Average, and 5% Poor), design features (43% Excellent, 35% Good, and 22% Average), simplicity of installation and disassembly (29% Excellent, 33% Good, and 38% Average), and ease of wearing/removing (45% Excellent, 40% Good, and 15%Average) are encouraging.

Challenges and future opportunities to unlock the critical supply chain of personal and protective equipment (PPE) encompassing decontamination and reuse under emergency use authorization (EUA) conditions during the COVID-19 pandemic: Through a reflective circularity and sustainability lens

Severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2), and the resulting coronavirus disease (COVID-19), was declared a public health emergency of global concern by the World Health Organization (WHO) in the early months of 2020. There was a marked lack of knowledge to inform national pandemic response plans encompassing appropriate disease mitigation and preparation strategies to constrain and manage COVID-19. For example, the top 16 "most cited" papers published at the start of the pandemic on core knowledge gaps collectively constitute a staggering 29,393 citations. Albeit complex, appropriate decontamination modalities have been reported and developed for safe reuse of personal and protective equipment (PPE) under emergency use authorization (EUA) where critical supply chain shortages occur for healthcare workers (HCWs) caused by the COVID-19 pandemic. Commensurately, these similar methods may provide solutions for the safe decontamination of enormous volumes of PPE waste promoting opportunities in the circular bioeconomy that will also protect our environment, habitats and natural capital. The co-circulation of the highly transmissive mix of COVID-19 variants of concern (VoC) will continue to challenge our embattled healthcare systems globally for many years to come with an emphasis placed on maintaining effective disease mitigation strategies. This viewpoint article addresses the rationale and key developments in this important area since the onset of the COVID-19 pandemic and provides an insight into a variety of potential opportunities to unlock the long-term sustainability of single-use medical devices, including waste management.

Photoactive decontamination and reuse of face masks

The corona virus disease 2019 (COVID-19) pandemic has led to global shortages in disposable respirators. Increasing the recycling rate of masks is a direct, low-cost strategy to mitigate COVID-19 transmission. Photoactive decontamination of used masks attracts great attention due to its fast response, remarkable virus inactivation effect and full protection integrity. Here, we review state-of-the-art situation of photoactive decontamination. The basic mechanism of photoactive decontamination is firstly discussed in terms of ultraviolet, photothermal or photocatalytic properties. Among which, ultraviolet radiation damages DNA and RNA to inactivate viruses and microorganisms, and photothermal method damages them by destroying proteins, while photocatalysis kills them by destroying the structure. The practical applications of photoactive decontamination strategies are then fully reviewed, including ultraviolet germicidal irradiation, and unconventional masks made of functional nanomaterials with photothermal or photocatalytic properties. Their performance requirements are elaborated together with the advantages of long-term recycle use. Finally, we put forward challenges and prospects for further development of photoactive decontamination technology.

Droplets Adhesion to Surgical Masks during Standard Oral Surgery

The most common routes of transmission of coronavirus disease 2019 are droplet and contact infections. During dental treatment, several instruments and procedures used generate droplets of saliva and blood, such as during the extraction of an impacted third molar (M3). Surgical masks are often used during tooth extraction. However, the surface structures of surgical masks against droplets are not fully understood. Therefore, we analyzed the droplets that adhered to the surgical masks during impacted M3 extraction using electron microscopy. The surgical mask was divided into three layers and observed using electron microscopy. The outer and inner layers had a similar mesh-like structure, whereas the middle layer had a denser three-dimensional structure. Droplets ranging from 20-100 µm in size, generated during the extraction, adhered to the fibers of the outer layer of the mask. Fewer droplets adhered to the middle layer than to the outer layer. Droplets did not reach the inner layer. In conclusion, we suggest that a surgical mask can prevent droplet infection when performing impacted M3 extraction. This study is expected to contribute to the study of infection control strategies during dental treatments in the future.

Biodegradable Electrospun Nanofiber Membranes as Promising Candidates for the Development of Face Masks

Aerosol particles, such as the widespread COVID-19 recently, have posed a great threat to humans. Combat experience has proven that masks can protect against viruses; however, the epidemic in recent years has caused serious environmental pollution from plastic medical supplies, especially masks. Degradable filters are promising candidates to alleviate this problem. Degradable nanofiber filters, which are developed by the electrospinning technique, can achieve superior filtration performance. This review focuses on the basic introduction to air filtration, the general aspects of face masks, and nanofibers. Furthermore, the progress of the state of art degradable electrospun nanofiber filters have been summarized, such as silk fibroin (SF), polylactic acid (PLA), chitosan, cellulose, and zein. Finally, the challenges and future development are highlighted.

The anti SARS-CoV-2 activity of nanofibrous filter materials activated with metal clusters

Nanofibrous filter materials were prepared by electrospinning a solution of 28 wt% poly(vinylidene fluoride) in N,N-dimethylacetamide with and without the addition of 2 wt% AgNO₃, Cu(NO₃)₂·2.5H₂O or ZnCl₂. X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectroscopy, thermogravimetric analysis, contact angle measurement, nitrogen sorption, and mercury intrusion porosimetry methods were used for the characterization of physical structure as well as the chemical composition of the electrospun materials. Particle filtration efficiency and antiviral activity against the SARS-CoV-2 alpha variant were tested in order to estimate the suitability of the prepared electrospun filter materials for application as indoor air filtration systems with virucidal properties. All filter materials prepared with salts demonstrated very high particle filtration efficiency (≥98.0%). The best antiviral activity was demonstrated by a material containing Cu(NO₃)₂·2.5H₂O in the spinning solution, which displayed the decrease in the number of infectious virions by three orders of magnitude after a contact time of 12 h. Materials with the addition of AgNO₃ and ZnCl₂ decreased the number of infectious virions after the same contact time by only ∼8 and ∼11 times, respectively.

Electrospun Filtering Membrane Designed as Component of Self-Decontaminating Protective Masks

The 2019 coronavirus outbreak and worsening air pollution have triggered the search for manufacturing effective protective masks preventing both particulate matter and biohazard absorption through the respiratory tract. Therefore, the design of advanced filtering textiles combining efficient physical barrier properties with antimicrobial properties is more newsworthy than ever. The objective of this work was to produce a filtering electrospun membrane incorporating a biocidal agent that would offer both optimal filtration efficiency and fast deactivation of entrapped viruses and bacteria. After the eco-friendly electrospinning process, polyvinyl alcohol (PVA) nanofibers were stabilized by crosslinking with 1,2,3,4-butanetetracarboxylic acid (BTCA). To compensate their low mechanical properties, nanofiber membranes with variable grammages were directly electrospun on a meltblown polypropylene (PP) support of 30 g/m². The results demonstrated that nanofibers supported on PP with a grammage of around only 2 g/m² presented the best compromise between filtration efficiencies of PM_0.3, PM_0.5, and PM_3.0 and the pressure drop. The filtering electrospun membranes loaded with benzalkonium chloride (ADBAC) as a biocidal agent were successfully tested against E. coli and S. aureus and against human coronavirus strain HCoV-229E. This new biocidal filter based on electrospun nanofibers supported on PP nonwoven fabric could be a promising solution for personal and collective protection in a pandemic context.

Upcycling face mask wastes generated during COVID-19 into value-added engineering materials: A review

Billions of disposable face masks (i.e., single-use masks) are used and discarded worldwide monthly due to the COVID-19 outbreak. The immethodical disposal of these polymer-based wastes containing non-biodegradable constituents (e.g., polypropylene) has provoked marked and severe damage to the ecosystem. Meanwhile, their ever-growing usage significantly strains the present-day waste management measures such as landfilling and incineration, resulting in large quantities of used face-covering masks landing in the environment as importunate contaminants. Hence, alternative waste management strategies are crucially demanded to decrease the negative impacts of face mask contamination. In this venue, developing high-yield, effective, and green routes toward recycling or upcycling face mask wastes (FMWs) into value-added materials is of great importance. While existing recycling processes assist the traditional waste management, they typically end up in materials with downgraded physicochemical, structural, mechanical, and thermal characteristics with reduced values. Therefore, pursuing potential economic upcycling processes would be more beneficial than waste disposal and/or recycling processes. This paper reviews recent advances in the FMWs upcycling methods. In particular, we focus on producing value-added materials via various waste conversion methods, including carbonization (i.e., extreme pyrolysis), pyrolysis (i.e., rapid carbonization), catalytic conversion, chemical treatment, and mechanical reprocessing. Generally, the upcycling methods are promising, firming the vital role of managing FMWs' fate and shedding light on the road of state-of-the-art materials design and synthesis.

A road map on synthetic strategies and applications of biodegradable polymers

Biodegradable polymers have emerged as fascinating materials due to their non-toxicity, environmentally benign nature and good mechanical strength. The toxic effects of non-biodegradable plastics paved way for the development of sustainable and biodegradable polymers. The engineering of biodegradable polymers employing various strategies like radical ring opening polymerization, enzymatic ring opening polymerization, anionic ring opening polymerization, photo-initiated radical polymerization, chemoenzymatic method, enzymatic polymerization, ring opening polymerization and coordinative ring opening polymerization have been discussed in this review. The application of biodegradable polymeric nanoparticles in the biomedical field and cosmetic industry is considered to be an emerging field of interest. However, this review mainly highlights the applications of selected biodegradable polymers like polylactic acid, poly(ε-caprolactone), polyethylene glycol, polyhydroxyalkanoates, poly(lactide-co-glycolide) and polytrimethyl carbonate in various fields like agriculture, biomedical, biosensing, food packaging, automobiles, wastewater treatment, textile and hygiene, cosmetics and electronic devices.

Unraveling the potential human health risks from used disposable face mask-derived micro/nanoplastics during the COVID-19 pandemic scenario: A critical review

With the global spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), disposable face masks (DFMs) have caused negative environmental impacts. DFMs will release microplastics (MPs) and nanoplastics (NPs) during environmental degradation. However, few studies reveal the release process of MPs/NPs from masks in the natural environment. This review presents the current knowledge on the abiotic and biotic degradation of DFMs. Though MPs and NPs have raised serious concerns about their potentially detrimental effects on human health, little attention was paid to their impacts on human health from DFM-derived MPs and NPs. The potential toxicity of mask-derived MPs/NPs, such as gastrointestinal toxicity, pneumotoxicity, neurotoxicity, hepatotoxicity, reproductive and transgenerational toxicity, and the underlying mechanism will be discussed in the present study. MPs/NPs serve as carriers of toxic chemicals and pathogens, leading to their bioaccumulation and adverse effects of biomagnification by food chains. Given human experiments are facing ethical issues and animal studies cannot completely reveal human characteristics, advanced human organoids will provide promising models for MP/NP risk assessment. Moreover, in-depth investigations are required to identify the release of MPs/NPs from discarded face masks and characterize their transportation through the food chains. More importantly, innovative approaches and eco-friendly strategies are urgently demanded to reduce DFM-derived MP/NP pollution.

The face behind the Covid-19 mask - A comprehensive review

The threat of epidemic outbreaks like SARS-CoV-2 is growing owing to the exponential growth of the global population and the continual increase in human mobility. Personal protection against viral infections was enforced using ambient air filters, face masks, and other respiratory protective equipment. Available facemasks feature considerable variation in efficacy, materials usage and characteristic properties. Despite their widespread use and importance, face masks pose major potential threats due to the uncontrolled manufacture and disposal techniques. Improper solid waste management enables viral propagation and increases the volume of associated biomedical waste at an alarming rate. Polymers used in single-use face masks include a spectrum of chemical constituents: plasticisers and flame retardants leading to health-related issues over time. Despite ample research in this field, the efficacy of personal protective equipment and its impact post-disposal is yet to be explored satisfactorily. The following review assimilates information on the different forms of personal protective equipment currently in use. Proper waste management techniques pertaining to such special wastes have also been discussed. The study features a holistic overview of innovations made in face masks and their corresponding impact on human health and environment. Strategies with SDG3 and SDG12, outlining safe and proper disposal of solid waste, have also been discussed. Furthermore, employing the CFD paradigm, a 3D model of a face mask was created based on fluid flow during breathing techniques. Lastly, the review concludes with possible future advancements and promising research avenues in personal protective equipment.

Nanotechnology Transition Roadmap toward Multifunctional Stimuli-Responsive Face Masks

In recent times, the use of personal protective equipment, such as face masks or respirators, is becoming more and more critically important because of common pollution; furthermore, face masks have become a necessary element in the global fight against the COVID-19 pandemic. For this reason, the main mission of scientists has become the development of face masks with exceptional properties that will enhance their performance. The versatility of electrospun polymer nanofibers has determined their suitability as a material for constructing "smart" filter media. This paper provides an overview of the research carried out on nanofibrous filters obtained by electrospinning. The progressive development of the next generation of face masks whose unique properties can be activated in response to a specific external stimulus is highlighted. Thanks to additional components incorporated into the fiber structure, filters can, for example, acquire antibacterial or antiviral properties, self-sterilize the structure, and store the energy generated by users. Despite the discovery of several fascinating possibilities, some of them remain unexplored. Stimuli-responsive filters have the potential to become products of large-scale availability and great importance to society as a whole.

Migration of Microplastics and Phthalates from Face Masks to Water

Since the outbreak of COVID-19, face masks have been introduced in the complex strategy of infection prevention and control. Face masks consist of plastic polymers and additives such as phthalates. The aim of this study was to evaluate the migration of microplastics (MP) and phthalates from face masks to water. Four types of masks including FFP2 masks and surgical were studied. Masks were first characterized to determine the different layers and the material used for their fabrication. Then, masks were cut into 20 pieces of 0.5 cm2, including all their layers, placed in water, and the migration of MP and phthalates was evaluated according to the conditions stated in EU Regulation No 10/2011 on plastic materials and articles intended to come into contact with food. For MP, the morphological analysis (shape, dimension, particle count) was performed using a stereomicroscope, while the identification of both masks and MP released was conducted using μ-Fourier-transform infrared spectroscopy (µ-FT-IR). Migration of phthalates was assessed by ultra-high-performance liquid chromatography coupled to triple quadrupole mass spectrometer (UPLC-MS/MS). Face masks analyzed in the present study were made of atactic polypropylene (PP) as stated by the manufacturer. The μ-FT-IR confirmed that PP and polyamide (PA) were released as fragments, while both PP and polyester (PES) were released as fibers. In addition, 4 phthalates were identified at concentrations between 2.34 and 21.0 µg/mask. This study shows that the migration study can be applied to evaluate the potential release of MP and phthalates from face masks to water and could give a hint for the potential impact of their incorrect disposal on the aquatic resources.

Uncovering the disposable face masks as vectors of metal ions (Pb(Ⅱ), Cd(Ⅱ), Sr(Ⅱ)) during the COVID-19 pandemic

The demand for disposable face masks (DFMs) increased sharply in response to the COVID-19 pandemic. However, information regarding the underlying roles of the largely discarded DFMs in the environment is extremely lacking. This study focused on the pristine and UV-aged DFMs as vectors of metal ions (Pb(Ⅱ), Cd(Ⅱ), and Sr(Ⅱ)). Further, the aging mechanism of DFMs with UV radiation as well as the interaction mechanisms between DFMs and metal ions were investigated. Results revealed that the aging process would help to promote more metal ions adsorbed onto DFMs, which was mainly attributed to the presence of oxygen-containing groups on the aged DFMs. The adsorption affinity of pristine and aged DFMs for the metal ions followed Pb(Ⅱ) > Cd(Ⅱ) > Sr(Ⅱ), which was positively corrected with the electronegativity of the metals. Interestingly, we found that even if DFMs were not disrupted, DFMs had similar or even higher adsorption affinity for metals compared with other existing microplastics. Besides, regarding environmental factors, including salinity and solution pH played a crucial role in the adsorption processes, with greater adsorption capacities for pristine and aged DFMs at higher pH values and low salinity. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory further confirmed that the pristine DFMs interacted with the metals mainly through electrostatic interaction, while electrostatic interaction and surface complexation jointly regulated the adsorption of the metals onto aged DFMs. Overall, these findings would help to evaluate environmental behaviors and risks of DFMs associated with metals.

Virucidal and Bactericidal Filtration Media from Electrospun Polylactic Acid Nanofibres Capable of Protecting against COVID-19

Electrospun nanofibres excel at air filtration owing to diverse filtration mechanisms, thereby outperforming meltblown fibres. In this work, we present an electrospun polylactide acid nanofibre filter media, FilterLayrTM Eco, displaying outstanding bactericidal and virucidal properties using Manuka oil. Given the existing COVID-19 pandemic, face masks are now a mandatory accessory in many countries, and at the same time, they have become a source of environmental pollution. Made by NanoLayr Ltd., FilterLayrTM Eco uses biobased renewable raw materials with products that have end-of-life options for being industrially compostable. Loaded with natural and non-toxic terpenoid from manuka oil, FilterLayr Eco can filter up to 99.9% of 0.1 µm particles and kill >99% of trapped airborne fungi, bacteria, and viruses, including SARS-CoV-2 (Delta variant). In addition, the antimicrobial activity, and the efficacy of the filter media to filtrate particles was shown to remain highly active following several washing cycles, making it a reusable and more environmentally friendly option. The new nanofibre filter media, FilterLayrTM Eco, met the particle filtration efficiency and breathability requirements of the following standards: N95 performance in accordance with NIOSH 42CFR84, level 2 performance in accordance with ASTM F2100, and level 2 filtration efficiency and level 1 breathability in accordance with ASTM F3502. These are globally recognized facemask and respirator standards.

Development of Monodispersed Polystyrene Particles as Thailand Reference Materials (TRM)

The purpose of this study was to develop monodispersed polystyrene particles as certified reference materials in accordance with the ISO 17034: 2016 and the ISO Guide 35. It can play a significant role especially during the COVID-19 pandemic since several covering items such as filtering facepiece respirators or medical masks must be investigated for the quality of operation by various sizes of polystyrene. The polystyrene particles were prepared in-house by National Nanotechnology Center (NANOTEC) using polymerization of styrene. Each batch was preliminary check for distribution, aggregation and averaged size by using dynamic light scattering. Then polystyrene particles were prepared to 1% solid suspension in deionized water for homogeneity testing, stability assessment and characterization using transmission electron microscope with ImageJ software. The 100 nm polystyrene as an example has been successfully synthesized fulfilled the criteria of size deviation from nominal value less than ± 10 nm and polydispersity index less than 0.05. Then, the particle size of polystyrene was statistically analyzed for screening test with the results of the coefficient of variation less than 10%. Stability assessment consisting of short-term stability testing with three different temperatures and long-term stability testing within 6 months observed was carried out. The results of short-term and long-term stability were presented within the maximum acceptable. The homogeneity tests for within bottle standard deviation and between bottle standard deviation were performed with randomly sampling. The results of homogeneity tests satisfied the criteria and therefore assigned the value as the certify value. Consequently, the certify value of 105.5 ± 4.6 nm of monodispersed polystyrene particles has been successfully developed as Thailand reference materials which were similar level of quality and accuracy to the standard commercial products.

Face Masks to Combat Coronavirus (COVID-19)-Processing, Roles, Requirements, Efficacy, Risk and Sustainability

Increasingly prevalent respiratory infectious diseases (e.g., COVID-19) have posed severe threats to public health. Viruses including coronavirus, influenza, and so on can cause respiratory infections. A pandemic may potentially emerge owing to the worldwide spread of the virus through persistent human-to-human transmission. However, transmission pathways may vary; respiratory droplets or airborne virus-carrying particles can have a key role in transmitting infections to humans. In conjunction with social distancing, hand cleanliness, and other preventative measures, the use of face masks is considered to be another scientific approach to combat ubiquitous coronavirus. Different types of face masks are produced using a range of materials (e.g., polypropylene, polyacrylonitrile, polycarbonate, polyurethane, polystyrene, polyester and polyethylene) and manufacturing techniques (woven, knitted, and non-woven) that provide different levels of protection to the users. However, the efficacy and proper disposal/management of the used face masks, particularly the ones made of non-biodegradable polymers, pose great environmental concerns. This review compiles the recent advancements of face masks, covering their requirements, materials and techniques used, efficacy, challenges, risks, and sustainability towards further enhancement of the quality and performance of face masks.

The environmental impact of mass coronavirus vaccinations: A point of view on huge COVID-19 vaccine waste across the globe during ongoing vaccine campaigns

The vaccine innovation is a ubiquitous preventive measure to the transmission of highly infectious SARS-COV-2. The ongoing mass coronavirus vaccination programmes have inadvertently become the bulk producers of biomedical and plastic waste triggering severe impact on the environment. The sustainable management of bio hazardous vaccine waste in particular; syringes, needles, used/un-used vials and single-use plastic equipment is of utmost importance. This perspective presents a critical point of view in terms of the generated vaccine waste and the subsequent knock-on effect on all aspects of ecosystem. The discussion includes dire consequences due to the release of huge amount of plastic-based personal protective equipment into marine environment. The pivotal crisis of CO₂ emission during the manufacture and storage of different vaccines has contributed to global warming. The unavoidable generation of microfibers upon incineration, autoclaving, pyrolysis and open dumping of vaccine waste has further jeopardized the environment. In this vein, exploration of biodegradable materials for vaccine inoculation and development of green technologies for sound waste management is suggested to mitigate the environment pollution.

Biodegradable Nanohybrid Materials as Candidates for Self-Sanitizing Filters Aimed at Protection from SARS-CoV-2 in Public Areas

The COVID-19 pandemic has raised the problem of efficient, low-cost materials enabling the effective protection of people from viruses transmitted through the air or via surfaces. Nanofibers can be a great candidate for efficient air filtration due to their structure, although they cannot protect from viruses. In this work, we prepared a wide range of nanofibrous biodegradable samples containing Ag (up to 0.6 at.%) and Cu (up to 20.4 at.%) exhibiting various wettability. By adjusting the magnetron current (0.3 A) and implanter voltage (5 kV), the deposition of TiO₂ and Ag⁺ implantation into PCL/PEO nanofibers was optimized in order to achieve implantation of Ag⁺ without damaging the nanofibrous structure of the PCL/PEO. The optimal conditions to implant silver were achieved for the PCL-Ti0.3-Ag-5kV sample. The coating of PCL nanofibers by a Cu layer was successfully realized by magnetron sputtering. The antiviral activity evaluated by widely used methodology involving the cultivation of VeroE6 cells was the highest for PCL-Cu and PCL-COOH, where the VeroE6 viability was 73.1 and 68.1%, respectively, which is significantly higher compared to SARS-CoV-2 samples without self-sanitizing (42.8%). Interestingly, the samples with implanted silver and TiO₂ exhibited no antiviral effect. This difference between Cu and Ag containing nanofibers might be related to the different concentrations of ions released from the samples: 80 μg/L/day for Cu²⁺ versus 15 µg/L/day for Ag⁺. The high antiviral activity of PCL-Cu opens up an exciting opportunity to prepare low-cost self-sanitizing surfaces for anti-SARS-CoV-2 protection and can be essential for air filtration application and facemasks. The rough cost estimation for the production of a biodegradable nanohybrid PCL-Cu facemask revealed ~$0.28/piece, and the business case for the production of these facemasks would be highly positive, with an Internal Rate of Return of 34%.

Reconciling human health with the environment while struggling against the COVID-19 pandemic through improved face mask eco-design

Surgical masks have become critical for protecting human health against the COVID-19 pandemic, even though their environmental burden is a matter of ongoing debate. This study aimed at shedding light on the environmental impacts of single-use (i.e., MD-Type I) versus reusable (i.e., MD-Type IIR) face masks via a comparative life cycle assessment with a cradle-to-grave system boundary. We adopted a two-level analysis using the ReCiPe (H) method, considering both midpoint and endpoint categories. The results showed that reusable face masks created fewer impacts for most midpoint categories. At the endpoint level, reusable face masks were superior to single-use masks, producing scores of 16.16 and 84.20 MPt, respectively. The main environmental impacts of single-use masks were linked to raw material consumption, energy requirements and waste disposal, while the use phase and raw material consumption made the most significant contribution for reusable type. However, our results showed that lower environmental impacts of reusable face masks strongly depend on the use phase since reusable face masks lost their superior performance when the hand wash scenario was tested. Improvement of mask eco-design emerged as another key factor such as using more sustainable raw materials and designing better waste disposal scenarios could significantly lower the environmental impacts.

Nanocellulose-based membrane as a potential material for high performance biodegradable aerosol respirators for SARS-CoV-2 prevention: a review

The controversy surrounding the transmission of COVID-19 in 2020 has revealed the need to better understand the airborne transmission route of respiratory viruses to establish appropriate strategies to limit their transmission. The effectiveness in protecting against COVID-19 has led to a high demand for face masks. This includes the single-use of non-degradable masks and Filtering Facepiece Respirators by a large proportion of the public, leading to environmental concerns related to waste management. Thus, nanocellulose-based membranes are a promising environmental solution for aerosol filtration due to their biodegradability, renewability, biocompatibility, high specific surface area, non-toxicity, ease of functionalization and worldwide availability. Although the technology for producing high-performance aerosol filter membranes from cellulose-based materials is still in its initial stage, several promising results show the prospects of the use of this kind of materials. This review focuses on the overview of nanocellulose-based filter media, including its processing, desirable characteristics and recent developments regarding filtration, functionalization, biodegradability, and mechanical behavior. The porosity control, surface wettability and surface functional groups resulting from the silylation treatment to improve the filtration capacity of the nanocellulose-based membrane is discussed. Future research trends in this area are planned to develop the air filter media by reinforcing the filter membrane structure of CNF with CNCs. In addition, the integration of sol-gel technology into the production of an air filter can tailor the pore size of the membrane for a viable physical screening solution in future studies.