Virucidal and biodegradable specialty cellulose nonwovens as personal protective equipment against COVID-19 pandemic

Recent Advances in Superhydrophobic and Antibacterial Cellulose-Based Fibers and Fabrics: Bio-inspiration, Strategies, and Applications

Cellulose-based fabrics are ubiquitous in our daily lives. They are the preferred choice for bedding materials, active sportswear, and next-to-skin apparels. However, the hydrophilic and polysaccharide characteristics of cellulose materials make them vulnerable to bacterial attack and pathogen infection. The design of antibacterial cellulose fabrics has been a long-term and on-going effort. Fabrication strategies based on the construction of surface micro-/nanostructure, chemical modification, and the application of antibacterial agents have been extensively investigated by many research groups worldwide. This review systematically discusses recent research on super-hydrophobic and antibacterial cellulose fabrics, focusing on morphology construction and surface modification. First, natural surfaces showing liquid-repellent and antibacterial properties are introduced and the mechanisms behind are explained. Then, the strategies for fabricating super-hydrophobic cellulose fabrics are summarized, and the contribution of the liquid-repellent function to reducing the adhesion of live bacteria and removing dead bacteria is elucidated. Representative studies on cellulose fabrics functionalized with super-hydrophobic and antibacterial properties are discussed in detail, and their potential applications are also introduced. Finally, the challenges in achieving super-hydrophobic antibacterial cellulose fabrics are discussed, and the future research direction in this area is proposed.

Graphical Abstract

The figure summarizes the natural surfaces and the main fabrication strategies of superhydrophobic antibacterial cellulose fabrics and their potential applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42765-023-00297-1.

Nano-copper ions assembled cellulose-based composite with antibacterial activity for biodegradable personal protective mask

The current SARS-CoV-2 pandemic has resulted in the widespread use of personal protective equipment, particularly face masks. However, the use of commercial disposable face masks puts great pressure on the environment. In this study, nano-copper ions assembled cotton fabric used in face masks to impart antibacterial activity has been discussed. To produce the nanocomposite, the cotton fabric was modified by sodium chloroacetate after its mercerization, and assembled with bactericidal nano-copper ions (about 10.61 mg·g-1) through electrostatic adsorption. It demonstrated excellent antibacterial activity against Staphylococcus aureus and Escherichia coli because the gaps between fibers in the cotton fabric allow the nano-copper ions to be fully released. Moreover, the antibacterial efficiency was maintained even after 50 washing cycles. Furthermore, the face mask constructed with this novel nanocomposite upper layer exhibited a high particle filtration efficiency (96.08% ± 0.91%) without compromising the air permeability (28.9 min·L-1). This green, economical, facile, and scalable process of depositing nano-copper ions onto modified cotton fibric has great potential to reduce disease transmission, resource consumption, and environmental impact of waste, while also expanding the range of protective fabrics.

Functional Fiber Membranes with Antibacterial Properties for Face Masks

Reusable face masks are an important alternative for minimizing costs of disposable and surgical face masks during pandemics. Often complementary to washing, a prolonged lifetime of face masks relies on the incorporation of self-cleaning materials. The development of self-cleaning face mask materials requires the presence of a durable catalyst to deactivate contaminants and microbes after long-term use without reducing filtration efficiency. Herein, we generate self-cleaning fibers by functionalizing silicone-based (polydimethylsiloxane, PDMS) fibrous membranes with a photocatalyst. Coaxial electrospinning is performed to fabricate fibers with a non-crosslinked silicone core within a supporting shell scaffold, followed by thermal crosslinking and removal of the water-soluble shell. Photocatalytic zinc oxide nanoparticles (ZnO NPs) are immobilized on the PDMS fibers by colloid-electrospinning or post-functionalization procedures. The fibers functionalized with ZnO NPs can degrade a photo-sensitive dye and display antibacterial properties against Gram-positive and Gram-negative bacteria (Escherichia coli and Staphylococcus aureus) due to the generation of reactive oxygen species upon irradiation with UV light. Furthermore, a single layer of functionalized fibrous membrane shows an air permeability in the range of 80-180 L/m2s and 65% filtration efficiency against fine particulate matter with a diameter less than 1.0 µm (PM1.0).

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s42765-023-00291-7.

Advancements of Nanotechnology and Nanomaterials in Environmental and Human Protection for Combatting the COVID-19 During and Post-pandemic Era: A Comprehensive Scientific Review

In December 2019, an outbreak of unknown pneumonia emerged in Wuhan City, Hubei Province, China. It was later identified as the SARS-CoV-2 virus and has since infected over 9 million people in more than 213 countries worldwide. Massive papers on the topic of SARS-CoV-2 that have already been published are necessary to be analyzed and discussed. This paper used the combination of systematic literature network analysis and content analysis to develop a comprehensive discussion related to the use of nanotechnology and materials in environmental and human protection. Its is shown that various efforts have been made to control the transmission of this pandemic. Nanotechnology plays a crucial role in modern vaccine design, as nanomaterials are essential tools for antigen delivery, adjuvants, and mimics of viral structures. In addition, nanomaterials and nanotechnology also reported a crucial role in environmental protection for defence and treating the pandemic. To eradicate pandemics now and in the future, successful treatments must enable rapid discovery, scalable manufacturing, and global distribution. In this review, we discuss the current approaches to COVID-19 development and highlight the critical role of nanotechnology and nanomaterials in combating the virus in the human body and the environment.

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.

A critical review on the interaction of polymer particles and co-existing contaminants: Adsorption mechanism, exposure factors, effects on plankton species

This review considers the interaction of microplastics (MPs)/nanoplastics (NPs) and co-existing contaminants, including organic contaminants, potentially toxic elements (PTEs), and metal/metal-oxide nanoparticles. Stronger adsorption between plastic particles and co-existing contaminants can either facilitate or prevent more contaminants to enter plankton. The characteristics of MPs/NPs, such as polymer type, size, functional groups, and weathering, affect combined effects. Mixture toxicity is affected by those factors simultaneously and also affected by the type of co-existing contaminants, their concentrations, exposure time, dissolved organic matter, and surfactant. For co-exposure involving organics and metal nanoparticles, marine Skeletonema costatum generally had antagonistic effects, while marine Chlorella pyrenoidosa, Platymonas subcordiformis, and Tetraselmis chuii, showed synergistic effects. For co-exposure involving organics and PTEs, both Chlorella sp. and Microcystis aeruginosa generally demonstrated antagonistic effects. Freshwater Chlorella reinhardtii and Scenedesmus obliquus had synergistic effects for co-exposure involving metal/metal oxide nanoparticles. Zooplankton shows more unpredicted sensitivity towards the complex system. Different co-existing contaminants have different metabolism pathways. Organic contaminants could be biodegraded, which may enhance or alleviate mixture toxicity. PTEs could be adsorbed and desorbed under changing environments, and further affect the combined effects. The presence of metal/metal-oxide nanoparticles is more complicated, since some may release ion metals, increasing contaminant composition.

Antimicrobial surface processing of polymethyl methacrylate denture base resin using a novel silica-based coating technology

OBJECTIVES

This study investigated the surface characteristics of denture base resin coatings prepared using a novel silica-based film containing hinokitiol and assessed the effect of this coating on Candida albicans adhesion and growth.

METHODS

Silica-based coating solutions (control solution; CS) and CS containing hinokitiol (CS-H) were prepared. C. albicans biofilm formed on denture base specimens coated with each solution and these uncoated specimens (control) were analyzed using colony-forming unit (CFU) assay, fluorescence microscopy, and scanning electron microscopy (SEM). Specimen surfaces were analyzed by measuring the surface roughness and wettability and with Fourier-transform infrared (FT-IR) and proton nuclear magnetic resonance (¹H NMR). Stability of coated specimens was assessed via immersion in water for 1 week for each group (control-1w, CS-1w, and CS-H-1w) followed by CFU assay, measurement of surface roughness and wettability, and FT-IR.

RESULTS

CS-H and CS-H-1w contained significantly lower CFUs than those present in the control and control-1w, which was also confirmed via SEM. Fluorescence microscopy from the CS-H group identified several dead cells. The values of surface roughness from coating groups were significantly less than those from the control and control-1w. The surface wettability from all coating groups exhibited high hydrophobicity. FT-IR analyses demonstrated that specimens were successfully coated, and ¹H NMR analyses showed that hinokitiol was incorporated inside CS-H.

CONCLUSIONS

A silica-based denture coating that incorporates hinokitiol inhibits C. albicans growth on denture.

CLINICAL RELEVANCE

We provide a novel antifungal denture coating which can be helpful for the treatment of denture stomatitis.

Generation and consequence of nano/microplastics from medical waste and household plastic during the COVID-19 pandemic

Since the end of 2019, the world has faced a major crisis because of the outbreak of COVID-19 disease which has created a severe threat to humanity. To control this pandemic, the World Health Organization gave some guidelines like wearing PPE (personal protective equipment) (e.g., face masks, overshoes, gloves), social distancing, hand hygiene and shutting down all modes of public transport services. During this pandemic, plastic products (e.g., household plastics, PPE and sanitizer bottles) have substantially prevented the spread of this virus. Since the outbreak, approximately 1.6 million tons of plastic waste have been generated daily. However, single-use PPE like face masks (N95), surgical masks and hand gloves contain many non-biodegradable plastics materials. These abandoned products have created a huge number of plastic debris which ended up as microplastics (MPs) followed by nanoplastics (NPs) in nature that are hazardous to the eco-system. These MPs and NPs also act as vectors for the various pathogenic contaminants. The goal of this review is to offer an extensive discussion on the formation of NPs and MPs from all of these abandoned plastics and their long-term impact on the environment as well as human health. This review paper also attempts to assess the present global scenario and the main challenge of waste management to reduce the potential NP/MPs pollution to improve the eco-systems.

Polymeric Materials as Indispensable Tools to Fight RNA Viruses: SARS-CoV-2 and Influenza A

Towards the end of 2019 in Wuhan, suspicions of a new dangerous virus circulating in the air began to arise. It was the start of the world pandemic coronavirus disease 2019 (COVID-19). Since then, considerable research data and review papers about this virus have been published. Hundreds of researchers have shared their work in order to achieve a better comprehension of this disease, all with the common goal of overcoming this pandemic. The coronavirus is structurally similar to influenza A. Both are RNA viruses and normally associated with comparable infection symptoms. In this review, different case studies targeting polymeric materials were appraised to highlight them as an indispensable tool to fight these RNA viruses. In particular, the main focus was how polymeric materials, and their versatile features could be applied in different stages of viral disease, i.e., in protection, detection and treatment.

Inspired by the Periodontium: A Universal Bacteria-Defensive Hydrogel for Preventing Percutaneous Device-Related Infection

Percutaneous device-related infection has greatly shortened the service period of devices and seriously reduced the quality of life of patients. Bacteria are one of the main pathogenic factors and cannot be effectively and conveniently eradicated by traditional strategies (e.g., construct coatings and introduce antibiotics), due to the complex interface among medical devices, surrounding tissue, and colonizing bacteria. Inspired by the periodontium, a universal bacteria-defensive hydrogel adapting to the complicated interface is fabricated by introducing phenol-amine chemistry to a polymeric matrix of N-hydroxyethyl acrylamide (HPC hydrogels). The HPC hydrogels with excellent toughness (2.1 MJ/m3), adhesion (10.2 and 13.2 kPa for pigskin and Ti-6Al-4V alloy, respectively), and antibacterial property (up to 99.9% for both Escherichia coli and Staphylococcus aureus) contributed to the innate microbe barrier via sealing the tissue-device interface and adaptive defense to eradicate bacteria. Meanwhile, bacterial invasion experiments demonstrate HPC hydrogels possess both a bacteria-defensive property (up to 24 h) and cell-protecting function at the same time. Furthermore, the biocompatibility of HPC hydrogels is verified in tests for in vitro cytotoxicity and in vivo irritation. Hence, the designed HPC hydrogels are considered as an emerging and universal candidate for preventing bacterial infection and can protect the deep tissue around a percutaneous device.

Copper-thiosemicarbazone complexes conjugated-cellulose fibers: Biodegradable materials with antibacterial capacity

Personal protective equipment (PPE) is vital in battling bacteria crisis, but conventional PPE materials lack antimicrobial activities and environmental friendliness. Our work focused on developing biodegradable and antibacterial fibers as promising bioprotective materials. Here, we grafted highly effective antibacterial copper-thiosemicarbazone complexes (CT1-4) on cellulose fibers via covalent linkages. Multiple methods were used to characterize the chemical composition or morphology of CT1-4 conjugated-fibers. Conjugation of CT1-4 maintains the mechanical properties (Breaking strength: 2.35-2.45 cN/dtex, Breaking elongation: 7.19 %-7.42 %) and thermal stability of fibers. CT1 can endow cellulose fibers with the excellent growth inhibition towards Escherichia coli (E. coli) (GIR: 61.5 % ± 1.28 %), Staphylococcus aureus (S. aureus) (GIR: 85.7 % ± 1.93 %), and Bacillus subtilis (B. subtilis) (GIR: 87.6 % ± 1.44 %). We believe that the application of CT1 conjugated-cellulose fibers is not limited to the high-performance PPE, and also can be extended to various types of protective equipment for food and medicine safety.

Polypropylene Modified with Ag-Based Semiconductors as a Potential Material against SARS-CoV-2 and Other Pathogens

The worldwide outbreak of the coronavirus pandemic (COVID-19) and other emerging infections are difficult and sometimes impossible to treat, making them one of the major public health problems of our time. It is noteworthy that Ag-based semiconductors can help orchestrate several strategies to fight this serious societal issue. In this work, we present the synthesis of α-Ag₂WO₄, β-Ag₂MoO₄, and Ag₂CrO₄ and their immobilization in polypropylene in the amounts of 0.5, 1.0, and 3.0 wt %, respectively. The antimicrobial activity of the composites was investigated against the Gram-negative bacterium Escherichia coli, the Gram-positive bacterium Staphylococcus aureus, and the fungus Candida albicans. The best antimicrobial efficiency was achieved by the composite with α-Ag₂WO₄, which completely eliminated the microorganisms in up to 4 h of exposure. The composites were also tested for the inhibition of SARS-CoV-2 virus, showing antiviral efficiency higher than 98% in just 10 min. Additionally, we evaluated the stability of the antimicrobial activity, resulting in constant inhibition, even after material aging. The antimicrobial activity of the compounds was attributed to the production of reactive oxygen species by the semiconductors, which can induce high local oxidative stress, causing the death of these microorganisms.

Zinc Oxide Nanoparticle-Loaded Electrospun Polyvinylidene Fluoride Nanofibers as a Potential Face Protector against Respiratory Viral Infections

ZnO-NPs loaded polyvinylidene fluoride (PVDF) composite nanofibers were fabricated by electrospinning and optimized using different concentrations (0, 2, and 5 wt %) of ZnO-NPs. Characterization techniques, for example, FTIR, SEM, XRD, and tensile strength analysis were performed to analyze the composite nanofibers. Molecular docking calculations were performed to evaluate the binding affinity of PVDF and ZnO@PVDF against the hexon protein of adenovirus (PDB ID: 6CGV). The cytotoxicity of tested materials was evaluated using MTT assay, and nontoxic doses subjected to antiviral evaluation against human adenovirus type-5 as a human respiratory model were analyzed using quantitative polymerase chain reaction assay. IC₅₀ values were obtained at concentrations of 0, 2, and 5% of ZnO-loaded PVDF; however, no cytotoxic effect was detected for the nanofibers. In 5% ZnO-loaded PVDF nanofibers, both the viral entry and its replication were inhibited in both the adsorption and virucidal antiviral mechanisms, making it a potent antiviral filter/mask. Therefore, ZnO-loaded PVDF nanofiber is a potentially prototyped filter embedded in a commercial face mask for use as an antiviral mask with a pronounced potential to reduce the spreading of infectious respiratory diseases, for example, COVID-19 and its analogues.