Antibacterial, Antiviral, and Self-Cleaning Mats with Sensing Capabilities Based on Electrospun Nanofibers Decorated with ZnO Nanorods and Ag Nanoparticles for Protective Clothing Applications

Comparison of Photocatalytic and Adsorption Properties of ZnS@ZnO, CdS@ZnO, and PbS@ZnO Nanocomposites to Select the Best Material for the Bifunctional Removal of Methylene Blue

In this study, photocatalytic- and adsorption-based removal processes were conducted, which are frequently preferred in wastewater treatment due to their ease of control and high removal efficiency. An innovative method aimed at wastewater treatment was developed by combining the advantages of these two distinct approaches within the same material. The study synthesized ZnO, ZnS, CdS, PbS, and their composite structures (ZnS@ZnO, CdS@ZnO, and PbS@ZnO) using a hydrothermal synthesis method. Characterization of the samples was performed through field emission-scanning electron microscopy (FE-SEM), FE-SEM-energy dispersive X-ray (FE-SEM-EDX), X-ray diffraction (XRD), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR) measurement. Additionally, the optical properties of all samples (absorption spectra and band gap) were investigated by using absorbance measurements obtained from ultraviolet (UV)-visible absorption spectroscopy. Although ZnO nanoparticles are among the materials with high photocatalytic properties (exhibiting a photodegradation efficiency of 95.8% in a short duration of 90 min), their adsorption properties are low. Therefore, with the aim of enhancing both the low adsorption values and the photocatalytic properties of pure metal sulfides (ZnS, CdS, PbS), nanocomposites ZnS@ZnO, CdS@ZnO, and PbS@ZnO with different morphologies were synthesized, and their photocatalytic and adsorption-based removal performances on methylene blue (MB) dye were investigated. FE-SEM images indicated that ZnS nanoparticles exhibit a spherical morphology, CdS nanoparticles have a flower-like morphology, and PbS nanoparticles display a dendritic-like structure. The results obtained from experimental studies demonstrated that the highest efficiency in both photocatalytic- and adsorption-based removal was achieved with the ZnS@ZnO nanocomposite. The degradation rates of MB were found to be 95.3, 90.5, and 89.4% for the heterojunction composites ZnS@ZnO, CdS@ZnO, and PbS@ZnO, respectively, over a time range of 0-480 min. The optimal amount of photocatalyst that could effectively degrade MB was determined to be 100 mg, and the reusability studies revealed that the ability of the ZnS@ZnO semiconductor heterojunction photocatalyst to decompose MB into simpler molecules was limited after the fourth cycle. The adsorption-based removal rates were 96.0, 30.5, and 19.4% for the heterojunction composites ZnS@ZnO, CdS@ZnO, and PbS@ZnO, respectively. Finally, parameters influencing the adsorption-based removal of MB, such as pH, mass, and contact time, were examined, indicating that the adsorption capacity of ZnS@ZnO remained unchanged after reaching a value of 40 mg·g-1.

Antibacterial nonwoven materials in medicine and healthcare

Bacterial infection has always been a severe challenge for mankind. The use of antibacterial nonwoven materials provides a lot of convenience in daily life and clinical practice grammar revision, it has become an important solution to avoid bacterial infection in clinical and daily life. This review systematically examines the spin bonding, melt blown, hydroneedling and electrospinning methods of nonwoven fabrication materials, and summarizes the antibacterial nonwoven materials fabrication methods. Finally, the review discusses the applications of antibacterial nonwoven materials for medical protection, external medical and healthcare, external circulation medical care implantable medical and healthcare and intelligent protection and detection. This comprehensive overview aims to provide valuable insights for the advancement of antibacterial nonwoven materials in the domain of medicine and health care. In the future, antibacterial nonwoven materials are expected to evolve towards biodegradability, composite materials, functionalization, minimally invasive techniques, diversification, and intelligence, thereby holding immense potential in healthcare.

Nanomaterial-functionalized electrospun scaffolds for tissue engineering

Tissue engineering has emerged as a biological alternative aimed at sustaining, rehabilitating, or enhancing the functionality of tissues that have experienced partial or complete loss of their operational capabilities. The distinctive characteristics of electrospun nanofibrous structures, such as their elevated surface-area-to-volume ratio, specific pore sizes, and fine fiber diameters, make them suitable as effective scaffolds in tissue engineering, capable of mimicking the functions of the targeted tissue. However, electrospun nanofibers, whether derived from natural or synthetic polymers or their combinations, often fall short of replicating the multifunctional attributes of the extracellular matrix (ECM). To address this, nanomaterials (NMs) are integrated into the electrospun polymeric matrix through various functionalization techniques to enhance their multifunctional properties. Incorporation of NMs into electrospun nanofibrous scaffolds imparts unique features, including a high surface area, superior mechanical properties, compositional variety, structural adaptability, exceptional porosity, and enhanced capabilities for promoting cell migration and proliferation. This review provides a comprehensive overview of the various types of NMs, the methodologies used for their integration into electrospun nanofibrous scaffolds, and the recent advancements in NM-functionalized electrospun nanofibrous scaffolds aimed at regenerating bone, cardiac, cartilage, nerve, and vascular tissues. Moreover, the main challenges, limitations, and prospects in electrospun nanofibrous scaffolds are elaborated.

A narrative review of personal protective equipment gowns: lessons from COVID-19

This narrative review evaluates the evidence regarding the protection offered by isolation gowns, approaches to imparting antimicrobial activity to gowns, and the environmental impacts of gown use, particularly during the COVID-19 pandemic. We conducted a search of the Medline, PubMed, and Google Scholar databases for articles published between January 1, 2019 to February 20, 2024. We found that current standards pertaining to isolation gowns might be irrelevant to the protection of healthcare workers from pathogen transmission, as they focus primarily on fluid barrier resistance values that are not reflective of all transmission conditions in hospitals. Although most available isolation gowns are disposable, reusable gowns could offer greater barrier protection and are more environmentally sustainable. Several techniques have been studied for their ability to impart antimicrobial properties to isolation gowns, extending their lifespan and reducing environmental impacts. However, evidence of the effectiveness of such techniques in clinical settings is scarce. We advocate for standardised guidelines inclusive of common pathogen survival tests, comfort, and durability, which reflect the actual infection risks encountered by healthcare workers, to improve the safety and efficacy of isolation gowns in hospital settings. Further research into the clinical effectiveness of antimicrobial gowns and their long-term implications on the environment is also warranted.

Electrospun multifunctional nanofibers for advanced wearable sensors

The multifunctional extension of fiber-based wearable sensors determines their integration and sustainable development, with electrospinning technology providing reliable, efficient, and scalable support for fabricating these sensors. Despite numerous studies on electrospun fiber-based wearable sensors, further attention is needed to leverage composite structural engineering for functionalizing electrospun fibers. This paper systematically reviews the research progress on fiber-based multifunctional wearable sensors in terms of design concept, device fabrication, mechanism exploration, and application potential. Firstly, the basics of electrospinning are briefly introduced, including its development, principles, parameters, and material selection. Tactile sensors, as crucial components of wearable sensors, are discussed in detail, encompassing their performance parameters, transduction mechanisms, and preparation strategies for pressure, strain, temperature, humidity, and bioelectrical signal sensors. The main focus of the article is on the latest research progress in multifunctional sensing design concepts, multimodal decoupling mechanisms, sensing mechanisms, and functional extensions. These extensions include multimodal sensing, self-healing, energy harvesting, personal thermal management, EMI shielding, antimicrobial properties, and other capabilities. Furthermore, the review assesses existing challenges and outlines future developments for multifunctional wearable sensors, highlighting the need for continued research and innovation.

Nanostructured Surfaces with Plasmonic Activity and Superhydrophobicity: Review of Fabrication Strategies and Applications

Plasmonics and superhydrophobicity have garnered broad interest from academics and industry alike, spanning fundamental scientific inquiry and practical technological applications. Plasmonic activity and superhydrophobicity rely heavily on nanostructured surfaces, providing opportunities for their mutually beneficial integration. Engineering surfaces at microscopic and nanoscopic length scales is necessary to achieve superhydrophobicity and plasmonic activity. However, the dissimilar surface energies of materials commonly used in fabricating plasmonic and superhydrophobic surfaces and different length scales pose various challenges to harnessing their properties in synergy. In this review, an overview of various techniques and materials that researchers have developed over the years to overcome this challenge is provided. The underlying mechanisms of both plasmonics and superhydrophobicity are first overviewed. Next, a general classification scheme is introduced for strategies to achieve plasmonic and superhydrophobic properties. Following that, applications of multifunctional plasmonic and superhydrophobic surfaces are presented. Lastly, a future perspective is presented, highlighting shortcomings, and opportunities for new directions.

Fluorescence Analysis of Antibacterial Activity of ZnO/TiO2 Electrospun Nanofibers: A Molecular Approach to Reveals the Insights of Physiochemical Interactions of Materials with Bacteria

Fluorescence spectroscopy employed to compute the antibacterial potential of pure ZnO and Titania (TiO2) loaded ZnO (TiO2: 2%, 4%, 6%, and 8%) electrospun nanofibers. The study of electrospun nanofibers followed by their structural, morphological and antibacterial properties has been revealed through fluorescence spectroscopy. X-ray diffraction (XRD) analysis of nanofibers calcinated at 600 °C revealed the presence of polycrystalline wurtzite hexagonal crystallographic planes of ZnO with preferred orientation along (101) direction. Scanning electron microscopy (SEM) confirmed that calcination of electrospun nanofibers resulted in smooth and pure ZnO nanofibers due to ethanol evaporation and polyvinylpyrrolidone (PVP) decomposition. Two bacterial strains Escherichia coli and Pseudomonas aeruginosa were used for fluorescence spectroscopy-based evaluation of antibacterial activity of ZnO and TiO2-ZnO nanofibers. Agar well technique was employed to investigate the antibacterial activity and functioning mechanism of nanofibers against Escherichia coli and Pseudomonas aeruginosa. The consistent zones of inhibition have been observed for pure ZnO and Titania loaded ZnO nanofibers. Fluorescence spectroscopy revealed the insights of bacterial killing with nanofibers. The mechanistic study of interaction between nanofibers and bacterial cells leads to cell membrane breakdown and confirmed with SEM imaged micrographs. Furthermore, the nanofibers calcinated at 600 °C efficiently ruptured the bacteria resulting in higher antibacterial phenomenon as compare to the other nanofiber structures.

Zinc Oxide-Loaded Recycled PET Nanofibers for Applications in Healthcare and Biomedical Devices

Polyethylene terephthalate (PET) is a widely utilized synthetic polymer, favored in various applications for its desirable physicochemical characteristics and widespread accessibility. However, its extensive utilization, coupled with improper waste disposal, has led to the alarming pollution of the environment. Thus, recycling PET products is essential for diminishing global pollution and turning waste into meaningful materials. Therefore, this study proposes the fabrication of electrospun membranes made of recycled PET nanofibers as a cost-effective valorization method for PET waste. ZnO nanoparticles were coated onto polymeric materials to enhance the antimicrobial properties of the PET fibers. Morphostructural investigations revealed the formation of fibrillar membranes made of unordered nanofibers (i.e., 40-100 nm in diameter), on the surface of which zinc oxide nanoparticles of 10-20 nm were attached. PET@ZnO membranes demonstrated effective antimicrobial and antibiofilm activity against Gram-positive and Gram-negative bacteria, yeasts, and molds, while imparting no toxicity to amniotic fluid stem cells. In vivo tests confirmed the materials' biocompatibility, as no side effects were observed in mice following membrane implantation. Altogether, these findings highlight the potential of integrating ZnO nanoparticles into recycled PET to develop multifunctional materials suitable for healthcare facilities (such as antimicrobial textiles) and biomedical devices, including applications such as textiles, meshes, and sutures.

Review on need for designing sustainable and biodegradable face masks: Opportunities for nanofibrous cellulosic filters

The surge in microbial illnesses, notably seen during the COVID-19 pandemic, has led to the global use of face masks-cloth, surgical, medical, and respirator types-to curb respiratory pathogen spread. Widely used by the public, patients, and healthcare workers, masks play a key role in reducing airborne transmission. However, synthetic, non-biodegradable materials in these masks have sparked environmental concerns due to disposal issues. Moreover, challenges like limited microbial filtration, poor fit, breathing resistance, and low reusability raise further issues, as does the failure to neutralize trapped microbes. Addressing these issues calls for high-performance, biodegradable masks crafted from renewable nanofibrous materials using advanced technology. Antimicrobial nanomaterial coatings can further reduce contamination risks for users and the environment. Nanofibrous materials, with their high surface area, enhance filtration, allow customization, and improve capture efficiency. Research is progressing on sustainable, biodegradable filters, particularly with cellulose materials. This review outlines mask types and limitations, spotlighting nanofibrous filters for their filtration efficiency, breathability, and sustainability. It also delves into nanofiber manufacturing and assesses bacterial cellulose-a promising renewable nanofibrous material suited for air filtration.

Fighting the flu: a brief review on anti-influenza agents

The influenza virus causes one of the most prevalent and lethal infectious viral diseases of the respiratory system; the disease progression varies from acute self-limiting mild fever to disease chronicity and death. Although both the preventive and treatment measures have been vital in protecting humans against seasonal epidemics or sporadic pandemics, there are several challenges to curb the influenza virus such as limited or poor cross-protection against circulating virus strains, moderate protection in immune-compromised patients, and rapid emergence of resistance. Currently, there are four US-FDA-approved anti-influenza drugs to treat flu infection, viz. Rapivab, Relenza, Tamiflu, and Xofluza. These drugs are classified based on their mode of action against the viral replication cycle with the first three being Neuraminidase inhibitors, and the fourth one targeting the viral polymerase. The emergence of the drug-resistant strains of influenza, however, underscores the need for continuous innovation towards development and discovery of new anti-influenza agents with enhanced antiviral effects, greater safety, and improved tolerability. Here in this review, we highlighted commercially available antiviral agents besides those that are at different stages of development including under clinical trials, with a brief account of their antiviral mechanisms.

Research Advances in Electrospun Nanofiber Membranes for Non-Invasive Medical Applications

Non-invasive medical nanofiber technology, characterized by its high specific surface area, biocompatibility, and porosity, holds significant potential in various medical domains, including tissue repair and biosensing. It is increasingly becoming central to healthcare by offering safer and more efficient treatment options for contemporary medicine. Numerous studies have explored non-invasive medical nanofibers in recent years, yet a comprehensive overview of the field remains lacking. In this paper, we provide a comprehensive summary of the applications of electrospun nanofibers in non-invasive medical fields, considering multiple aspects and perspectives. Initially, we introduce electrospinning nanofibers. Subsequently, we detail their applications in non-invasive health, including health monitoring, personal protection, thermal regulation, and wound care, highlighting their critical role in improving human health. Lastly, this paper discusses the current challenges associated with electrospun nanofibers and offers insights into potential future development trajectories.

Cu-ZnO Embedded in a Polydopamine Shell for the Generation of Antibacterial Surgical Face Masks

A new easy protocol to functionalize the middle layer of commercial surgical face masks (FMs) with Zn and Cu oxides is proposed in order to obtain antibacterial personal protective equipment. Zinc and copper oxides were synthesized embedded in a polydopamine (PDA) shell as potential antibacterial agents; they were analyzed by XRD and TEM, revealing, in all the cases, the formation of metal oxide nanoparticles (NPs). PDA is a natural polymer appreciated for its simple and rapid synthesis, biocompatibility, and high functionalization; it is used in this work as an organic matrix that, in addition to stabilizing NPs, also acts as a diluent in the functionalization step, decreasing the metal loading on the polypropylene (PP) surface. The functionalized middle layers of the FMs were characterized by SEM, XRD, FTIR, and TXRF and tested in their bacterial-growth-inhibiting effect against Klebsiella pneumoniae and Staphylococcus aureus. Among all functionalizing agents, Cu2O-doped-ZnO NPs enclosed in PDA shell, prepared by an ultrasound-assisted method, showed the best antibacterial effect, even at low metal loading, without changing the hydrophobicity of the FM. This approach offers a sustainable solution by prolonging FM lifespan and reducing material waste.

Morinda citrifolia leaf assisted synthesis of ZnO decorated Ag bio-nanocomposites for in-vitro cytotoxicity, antimicrobial and anticancer applications

This study used Morinda citrifolia leaf (MCL) extract to synthesise Zinc oxide nanoparticles (ZnO NPs) and ZnO decorated silver nanocomposites (ZnO/Ag NCs). The synthesized nanomaterials structural morphology and crystallinity were characterized using a Field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) analysis. The antimicrobial activity of ZnO NPs and ZnO/Ag NCs was evaluated using human nosocomial bacterial pathogens. The highest antimicrobial activity was recorded for ZnO/Ag NCs at the minimum inhibitory concentration (MIC) at 80 and 100 μg/mL for Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis, Staphylococcus aureus than ZnO NPs at the MIC of 120 and 140 μg/mL for Bacillus subtilis and Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus. Furthermore, ROS detection, viability assay and bacterial membrane integrity analysis of ZnO/Ag NCs treated P. aeruginosa and S. aureus revealed the fundamental bactericidal mechanism involving cell wall, cell membrane interaction and release of cytoplasmic contents. In addition, ZnO/Ag NCs and ZnO NPs showed higher toxicity towards A549 lung cancer cells than the non-cancerous RAW264 macrophage cells, with IC50 of 242 and 398 µg/mL respectively, compared to IC50 of 402 and 494 µg/mL for the macrophage cells. These results suggest that the ZnO/Ag NCs can be effectively used to develop antimicrobial and anticancer materials.

Preparation and Property Analysis of Antibacterial Fiber Membranes Based on Hyperbranched Polymer Quaternary Ammonium Salts

Due to their excellent properties, antimicrobial fiber membranes are widely applied in bioprotective materials. This work addresses the preparation of thermoplastic polyurethane (TPU)-based fiber membranes with active antimicrobial properties. 2-hydroxypropyl trimethyl ammonium chloride-terminated hyperbranched polymer (HBP-HTC) was synthesized and used as an antimicrobial agent. The fiber membranes were obtained by electrospinning a mixed solution of HBP-HTC and TPU. Different electrospinning conditions were investigated, such as the spinning voltage and drum rotation speed. The fiber membrane prepared under a 22 kV anode voltage and 100 rpm rotation speed had an average fiber diameter of 1.66 μm with a concentrated diameter distribution. Antibacterial tests showed that when the fiber membrane was loaded with 1500 mg/kg of HBP-HTC, the antibacterial rates of E. coli as well as S. aureus both reached 99.99%, exhibiting excellent proactive antimicrobial performance. Moreover, the protective performance of the fiber membrane was outstanding, with a filtration efficiency of 99.9%, a hydrostatic pressure resistance greater than 16,758 Pa, and a moisture permeability of 2711.0 g⋅(m2⋅d)-1.

Apt-Conjugated PDMS-ZnO/Ag-Based Multifunctional Integrated Superhydrophobic Biosensor with High SERS Activity and Photocatalytic Sterilization Performance

Sensitive detection and efficient inactivation of pathogenic bacteria are crucial for halting the spread and reproduction of foodborne pathogenic bacteria. Herein, a novel Apt-modified PDMS-ZnO/Ag multifunctional biosensor has been developed for high-sensitivity surface-enhanced Raman scattering (SERS) detection along with photocatalytic sterilization towards Salmonella typhimurium (S. typhimurium). The distribution of the electric field in PDMS-ZnO/Ag with different Ag sputtering times was analyzed using a finite-difference time-domain (FDTD) algorithm. Due to the combined effect of electromagnetic enhancement and chemical enhancement, PDMS-ZnO/Ag exhibited outstanding SERS sensitivity. The limit of detection (LOD) for 4-MBA on the optimal SERS substrate (PZA-40) could be as little as 10-9 M. After PZA-40 was modified with the aptamer, the LOD of the PZA-40-Apt biosensor for detecting S. typhimurium was only 10 cfu/mL. Additionally, the PZA-40-Apt biosensor could effectively inactivate S. typhimurium under visible light irradiation within 10 min, with a bacterial lethality rate (Lb) of up to 97%. In particular, the PZA-40-Apt biosensor could identify S. typhimurium in food samples in addition to having minimal cytotoxicity and powerful biocompatibility. This work provides a multifunctional nanoplatform with broad prospects for selective SERS detection and photocatalytic sterilization of pathogenic bacteria.

A one-step method for generating antimicrobial nanofibre meshes via coaxial electrospinning

Respiratory diseases, including influenza, infectious pneumonia, and severe acute respiratory syndrome (SARS), are a leading cause of morbidity and mortality worldwide. The recent COVID-19 pandemic claimed over 6.9 million lives globally. With the possibility of future pandemics, the creation of affordable antimicrobial meshes for protective gear, such as facemasks, is essential. Electrospinning has been a focus for much of this research, but most approaches are complex and expensive, often wasting raw materials by distributing antiviral agents throughout the mesh despite the fact they can only be active if at the fibre surface. Here, we report a low cost and efficient one-step method to produce nanofibre meshes with antimicrobial activity, including against SARS-CoV-2. Cetrimonium bromide (CTAB) was deposited directly onto the surface of polycaprolactone (PCL) fibres by coaxial electrospinning. The CTAB-coated samples have denser meshes with finer nanofibres than non-coated PCL fibres (mean diameter: ∼300 nm versus ∼900 nm, with mean pore size: ∼300 nm versus > 600 nm). The formulations have > 90% coating efficiency and exhibit a burst release of CTAB upon coming into contact with aqueous media. The CTAB-coated materials have strong antibacterial activity against Staphylococcus aureus (ca. 100%) and Pseudomonas aeruginosa (96.5 ± 4.1%) bacteria, as well as potent antiviral activity with over 99.9% efficacy against both respiratory syncytial virus and SARS-CoV-2. The CTAB-coated nanofibre mesh thus has great potential to form a mask material for preventing both bacterial and viral respiratory infections.

Progress in the Preparation and Application of Breathable Membranes

Breathable membranes with micropores enable the transfer of gas molecules while blocking liquids and solids, and have a wide range of applications in medical, industrial, environmental, and energy fields. Breathability is highly influenced by the nature of a material, pore size, and pore structure. Preparation methods and the incorporation of functional materials are responsible for the variety of physical properties and applications of breathable membranes. In this review, the preparation methods of breathable membranes, including blown film extrusion, cast film extrusion, phase separation, and electrospinning, are discussed. According to the antibacterial, hydrophobic, thermal insulation, conductive, and adsorption properties, the application of breathable membranes in the fields of electronics, medicine, textiles, packaging, energy, and the environment are summarized. Perspectives on the development trends and challenges of breathable membranes are discussed.

Zn/Al layered double hydroxide and carboxymethyl cellulose composite beads as support for the catalytic gold nanoparticles and their applications in the reduction of nitroarenes

Until now, many efficient catalysts have been reported that are used for the reduction of nitroarenes. However, a catalyst reusability is a challenge that is often faced in practical environment. In this report, we designed a hydrogel composite (CMC-LDH), which act as support and making it possible to address this challenge. In this research work, zinc/aluminum based layered double hydroxides (Zn/Al LDH) have been assembled with carboxymethyl cellulose (CMC) to prepare CMC/LDH hydrogel beads. The CMC/LDH hydrogel beads were prepared by the ionotropic gelation method. For CMC/LDH/Au preparation, the already prepared CMC/LDH beads were kept in gold ion (Au3+) solution, and their subsequent reduction with sodium borohydride (NaBH4). For the characterization of the prepared samples different instrumental techniques, such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy, and scanning electron microscopy (SEM) were adopted. For the catalytic evaluation of CMC/LDH/Au, it was utilized as a catalyst in 4-NP and 4-NA reduction reactions. The continuity of the reaction was monitored by a UV-visible spectrophotometer. Rate constant (kapp) of 0.48474 min-1 and 0.7486 min-1 were obtained for 4-NP and 4-NA reduction, respectively. The hydrogel beads were recycled and reused for up to five successive cycles without significantly changing their catalytic efficiency.

Nanofiberous facemasks as protectives against pandemic respiratory viruses

INTRODUCTION

Wearing protective face masks and respirators has been a necessity to reduce the transmission rate of respiratory viruses since the outbreak of the coronavirus (COVID-19) disease. Nevertheless, the outbreak has revealed the need to develop efficient air filter materials and innovative anti-microbial protectives. Nanofibrous facemasks, either loaded with antiviral nanoparticles or not, are very promising personal protective equipment (PPE) against pandemic respiratory viruses.

AREAS COVERED

In this review, multiple types of face masks and respirators are discussed as well as filtration mechanisms of particulates. In this regard, the limitations of traditional face masks were summarized and the advancement of nanotechnology in developing nanofibrous masks and air filters was discussed. Different methods of preparing nanofibers were explained. The various approaches used for enhancing nanofibrous face masks were covered.

EXPERT OPINION

Although wearing conventional face masks can limit viral infection spread to some extent, the world is in great need for more protective face masks. Nanofibers can block viral particles efficiently and can be incorporated into face masks in order to enhance their filtration efficiency. Also, we believe that other modifications such as addition of antiviral nanoparticles can significantly increase the protection power of facemasks.

Electrospinning Silk-Fibroin-Based Fibrous Membranes with AgNPs for Antimicrobial Application

Silk fibroin (SF) has excellent biocompatibility and is one of the most commonly used polymer materials. However, SF fibers have serious drawbacks as antibacterial materials due to their lack of stability and bacterial resistance. Therefore, it is of paramount significance to enhance the stability and bolster the bacterial resistance of SF fibers. In this study, SF fibers were fabricated and loaded with Ag nanoparticles (AgNPs) to improve the antimicrobial properties of the fibers. The impact of reduction conditions on the size of AgNPs was also investigated. In an antibacterial test, the fibers that were prepared exhibited over 98% bacterial resistance against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Therefore, as an efficient antibacterial material, these fibers are expected to become a candidate material in medical and textile fields. This study offers a novel approach for the utilization of SF fibers in the realm of antibacterial applications.

Graphene-Wrapped ZnO Nanocomposite with Enhanced Room-Temperature Photo-Activated Toluene Sensing Properties

Graphene-wrapped ZnO nanocomposites were fabricated by a simple solvothermal technology with a one-pot route. The structure and morphology of these as-fabricated samples were systematically characterized. The adding of graphene enhanced the content of the oxygen vacancy defect of the sample. All gas-sensing performances of sensors based on as-prepared samples were thoroughly studied. Sensors displayed an ultrahigh response and exceptional selectivity at room temperature under blue light irradiation. This excellent and enhanced toluene gas-sensing property was principally attributed to the synergistic impacts of the oxygen vacancy defect and the wrapped graphene in the composite sensor. The photo-activated graphene-wrapped ZnO sensor illustrated potential application in the practical detection of low concentrations of toluene under explosive environments.

Silver Nanoparticles In Situ Synthesized and Incorporated in Uniaxial and Core-Shell Electrospun Nanofibers to Inhibit Coronavirus

In the present study, we sought to develop materials applicable to personal and collective protection equipment to mitigate SARS-CoV-2. For this purpose, AgNPs were synthesized and stabilized into electrospinning nanofiber matrices (NMs) consisting of poly(vinyl alcohol) (PVA), chitosan (CHT), and poly-ε-caprolactone (PCL). Uniaxial nanofibers of PVA and PVA/CHT were developed, as well as coaxial nanofibers of PCL[PVA/CHT], in which the PCL works as a shell and the blend as a core. A crucial aspect of the present study is the in situ synthesis of AgNPs using PVA as a reducing and stabilizing agent. This process presents few steps, no additional toxic reducing agents, and avoids the postloading of drugs or the posttreatment of NM use. In general, the in situ synthesized AgNPs had an average size of 11.6 nm, and the incorporated nanofibers had a diameter in the range of 300 nm, with high uniformity and low polydispersity. The NM's spectroscopic, thermal, and mechanical properties were appropriate for the intended application. Uniaxial (PVA/AgNPs and PVA/CHT/AgNPs) and coaxial (PCL[PVA/CHT/AgNPs]) NMs presented virucidal activity (log's reduction ≥ 5) against mouse hepatitis virus (MHV-3) genus Betacoronavirus strains. In addition to that, the NMs did not present cytotoxicity against fibroblast cells (L929 ATCC® CCL-1TM lineage).

Fabrication of biodegradable cellulose acetate nanofibers containing Rose Bengal dye by electrospinning technique and their antiviral efficacy under visible light irradiation

Biodegradable cellulose acetate (CA) nanofibers containing Rose Bengal (RB) dye were fabricated by electrospinning technique. RB dye, an anionic photosensitizer, has been used in photodynamic therapy due to its excellent biocompatibility and ability to absorb light to generate reactive oxygen species (ROS), but has a decisive disadvantage of water solubility on infection prevention. Firstly, water-insoluble RB dye was synthesized through complexation with cationic ionic liquid (IL) for antiviral agents. The synthesized water-insoluble RB dyes were embedded into biodegradable CA nanofibers by electrospinning. The electrospun nanofibers passed both antiviral test for φx174 virus under visible light irradiation and biodegradability-test using enzymes. The fabricated RB nanofibers absorbed light and generated ROS to inactivate the virus. As a result, the log reduction (-Log10(N/N0)) of φx174 titer under visible light reached a detection limit of 5.00 within 30 min. Also, the fabricated nanofibers were degraded up to 34 wt % in 9 weeks by lipase and cellulase enzymes compared with non-biodegradable nanofibers.

Biosurfactant-capped CuO nanoparticles coated cotton/polypropylene fabrics toward antimicrobial textile applications

The global COVID-19 pandemic has led to an increase in the importance of implementing effective measures to prevent the spread of microorganisms. Consequently, there is a growing demand for antimicrobial materials, specifically antimicrobial textiles and face masks, because of the surge in diseases caused by bacteria and viruses like SARS-CoV-2. Face masks that possess built-in antibacterial properties can rapidly deactivate microorganisms, enabling reuse and reducing the incidence of illnesses. Among the numerous types of inorganic nanomaterials, copper oxide nanoparticles (CuO NPs) have been identified as cost-effective and highly efficient antimicrobial agents for inactivating microbes. Furthermore, biosurfactants have recently been recognized for their potential antimicrobial effects, in addition to inorganic nanoparticles. Therefore, this research's primary focus is synthesizing biosurfactant-mediated CuO NPs, integrating them into natural and synthetic fabrics such as cotton and polypropylene and evaluating the resulting fabrics' antimicrobial activity. Using rhamnolipid (RL) as a biosurfactant and employing a hydrothermal method with a pH range of 9-11, RL-capped CuO NPs are synthesized (RL-CuO NPs). To assess their effectiveness against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) microorganisms, the RL-CuO NPs are subjected to antibacterial testing. The RL-capped CuO NPs exhibited antimicrobial activity at much lower concentrations than the individual RL, CuO. RL-CuO NPs have shown a minimum inhibitory concentration (MIC) of 1.2 mg ml-1and minimum bactericidal concentration (MBC) of 1.6 mg ml-1forE. coliand a MIC of 0.8 mg ml-1and a MBC of 1.2 mg ml-1forS. aureus, respectively. Furthermore, the developed RL-CuO NPs are incorporated into cotton and polypropylene fabrics using a screen-printing technique. Subsequently, the antimicrobial activity of the coated fabrics is evaluated, revealing that RL-CuO NPs coated fabrics exhibited remarkable antibacterial properties against both gram-positive and gram-negative bacteria.

Antibacterial and Antiviral Activities of Silver Nanocluster/Silica Composite Coatings Deposited onto Air Filters

The indoor air quality should be better controlled and improved to avoid numerous health issues. Even if different devices are developed for air filtration, the proliferation of microorganisms under certain conditions must be controlled. For this purpose, a silver nanocluster/silica composite coating was deposited via a cosputtering technique onto fiber glass and polymeric based substrates. The aim of this work is focused on the evaluation of the antibacterial and antiviral effects of the developed coating. The preliminary results of the compositional and morphological tests showed an evenly distributed coating on filters surfaces. Several antibacterial tests were performed, confirming strong effect both in qualitative and quantitative methods, against S. epidermidis and E. coli. To understand if the coating can stop the proliferation of bacteria colonies spread on it, simulation of everyday usage of filters was performed, nebulizing bacteria solution with high colonies concentration and evaluating the inhibition of bacteria growth. Additionally, a deep understanding of the virucidal action and mechanism of Ag nanoclusters of the coating was performed. The effect of the coating both in aqueous medium and in dry methods was evaluated, in comparison with analysis on ions release. The virucidal performances are assessed against the human coronavirus OC43 strain (HCoV-OC43).

Selenium nanoparticles incorporated in nanofibers media eliminate H1N1 activity: a novel approach for virucidal antiviral and antibacterial respiratory mask

The consecutive viral infectious outbreaks impose severe complications on public health besides the economic burden which led to great interest in antiviral personal protective equipment (PPE). Nanofiber-based respiratory mask has been introduced as a significant barrier to eliminate the airborne transmission from aerosols toward reduction the viral infection spreading. Herein, selenium nanoparticles incorporated in polyamide 6 nanofibers coated on spunbond nonwoven were synthesized via electrospinning technique (PA6@SeNPs), with an average diameter of 180 ± 2 nm. The nanofiber-coated media were tested for 0.3 μm particulate filtration efficiency based on Standard NIOSH (42 CFR 84). PA6@SeNPs had a pressure drop of 45 ± 2 Pa and particulate filtration efficiency of more than 97.33 which is comparable to the N95 respiratory mask. The bacterial killing efficiency of these nanofibers was 91.25% and 16.67% against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), respectively. Furthermore, the virucidal antiviral test for H1N1 infected Madin-Darby Canine Kidney cells (MDCK) exhibited TCID50 of 108.13, 105.88, and 105.5 for 2, 10, and 120 min of exposure times in comparison with 108.5, 107.5, and 106.5 in PA6 nanofibers as control sample. MTT assay indicated excellent biocompatibility of electrospun PA6@SeNP nanofibers on L292 cells. These results propose the PA6@SeNP nanofibers have a high potential to be used as an efficient layer in respiratory masks for protection against respiratory pathogens.

A tailored slow-release film with synergistic antibacterial and antioxidant activities for ultra-persistent preservation of perishable products

Rapid decrease in antibacterial efficacy of existing active packages is difficult to promisingly prevent microbial infection during the storage of perishable products. Here, we pioneered an advanced ZnO-doped hollow carbon-encapsulated curcumin (ZHC-Cur)-chitosan (CS) slow-release film (ZHC-Cur-CS) with "nano-barricade" structure through demand-oriented tailoring of the structure and components of zeolitic imidazolate framework-8 (ZIF-8) carrier. Such an exquisite structure realized the effective sustained release of Curcumin through the dual complexity of diffusion pathway by the disordered hierarchical pore structure and steric hindrance. Prepared ZHC-Cur-CS film exhibited boosting bactericidal and antioxidant abilities by virtue of the functional synergy between curcumin and ZnO. Thus, ZHC-Cur-CS film demonstrated excellent preservation performance by significantly prolonging the shelf life of Citrus (∼2.4 times). Furthermore, the upgraded mechanical strength, improved barrier ability, and proven safety laid the foundation for its practical application. These satisfactory properties underscore the applicability of ZHC-Cur-CS film for the efficient preservation of perishable products.

Preparation of arginine-loaded mesoporous silica nanoparticles (Arg@MSNs) to improve the mechanical and antibacterial properties of denture base resin

STATEMENT OF PROBLEM

Whether the incorporation of arginine-loaded mesoporous silica nanoparticles (Arg@MSNs) into denture base resin can improve the mechanical and antibacterial properties is unclear.

PURPOSE

The purpose of this in vitro study was to synthesis Arg@MSNs and explore how Arg@MSNs incorporation affects the mechanical and antibacterial properties of denture base resin.

MATERIAL AND METHODS

Arg@MSNs were synthesized via a sol-gel process and characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD). The prepared Arg@MSNs at different weight ratio concentrations were added into denture base resin as the experimental group, and unmodified denture base resin was the control. The fracture surface and arginine release behavior of each specimen were detected using scanning electron microscopy (SEM) and ultra-high-performance liquid chromatography-tandem mass spectrometer (UHPLC-HESI-MS/MS), respectively. Three-point bend tests were applied using a universal testing machine for evaluation of the mechanical properties of each group (n=5). Antibacterial efficiency (n=3) was evaluated by both quantitative and qualitative analysis using Streptococcus mutans. The cytotoxic effect of the Arg@MSN-modified denture base resin was investigated using a cell counting kit (CCK)-8 test. Data were subjected to 1-way analysis of variance followed by the post hoc Tukey honestly significant difference test (ɑ=.05).

RESULTS

The prepared Arg@MSNs had good monodispersity and spherical morphology. Arg@MSN concentration at 0.5 wt%, 1 wt%, and 2.5 wt% resulted in enhanced mechanical properties, while those at 5 wt% were adversely impacted. Biofilm pH values increased with the incorporation of Arg@MSNs, and the antibacterial performance was improved. The CCK-8 test revealed that all formulations were not cytotoxic.

CONCLUSIONS

The addition of Arg@MSNs into denture base resin can enhance its mechanical properties and improve its antibacterial performance without any apparent cytotoxic effect.

Antibacterial and Photocatalytic Activity of ZnO/Au and ZnO/Ag Nanocomposites

The use of a combination of nanoparticles as antimicrobial agents can be one strategy to overcome the tendency of microbes to become resistant to antibiotic action. Also, the optimization of nano-photocatalysts to efficiently remove persistent pollutants from wastewater is a hot topic. In this study, two composites ZnO/Au (1% wt.) and ZnO/Ag (1% wt.) were synthesized by simple aqueous solution methods. The structure and morphology of the r nanocomposites were analyzed by structural and optical characterization methods. The formation of AuNPs and AgNPs in these experiments was also discussed. The antimicrobial properties of ZnO, ZnO/Au, and ZnO/Ag nanomaterials were investigated against Gram-negative bacteria (Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus). The results showed an increase of 80% in the antimicrobial activity of ZnO/Au against Pseudomonas aeruginosa compared with 30% in the case of ZnO/Ag. Similarly, in the case of the S. aureus strain tests, ZnO/Au increased the antimicrobial activity by 55% and ZnO/Ag by 33%. The photocatalytic tests indicated an improvement in the photocatalytic degradation of methylene blue (MB) under UV irradiation using ZnO/Au and ZnO/Ag nanocomposites compared to bare ZnO. The photocatalytic degradation efficiency of ZnO after 60 min of UV irradiation was ∼83%, while the addition of AuNPs enhanced the degradation rate to ∼95% (ZP2), and AgNP presence enhanced the efficiency to ∼98%. The introduction of noble metallic nanoparticles into the ZnO matrix proved to be an effective strategy to increase their antimicrobial activity against P. aeruginosa and S. aureus, and their photocatalytic activity was evaluated through the degradation of MB dye. Comparing the enhancing effects of Au and Ag, it was found that ZnO/Au was a better antimicrobial agent while ZnO/Ag was a more effective photocatalyst under UV irradiation.

Assessing the contribution of semiconductors to the sustainable development goals (SDGs) from 2017 to 2022

Semiconductor development is a major driving force for global economic growth. However, synchronizing it with the Sustainable Development Goals (SDGs) set by the United Nations remains a critical challenge. To gain insight into this, we analyzed SDG-related publications on semiconductors from 2017 to 2022 using the SciVal database. The study found 77,706 documents related to SDGs in the field of semiconductor research, with an overall increase in the number of publications each year. The main focus of these publications was SDG 7 (Affordable and Clean Energy), accounting for 68.9 % of the total publication count. Additionally, the results indicate that semiconductors have multifaceted potential in advancing a range of SDGs. From fostering innovations in healthcare (SDG 3), ensuring clean water access (SDG 6), catalyzing transformative industrial growth (SDG 9), to contributing to climate mitigation strategies (SDG 13), semiconductors emerge as versatile drivers of sustainable development. The respective publication percentages for these goals were 7.3 %, 5.9 %, 9.7 %, and 4.4 %, underscoring their capacity to make substantial contributions across various facets of sustainability. It's worth noting that only 2.9 % of these publications stem from academia-industry collaborations. This indicates a pressing need to facilitate collaboration between academia and industry, as such partnerships have the potential to amplify the impact of semiconductor innovations on the SDGs. The novelty of this study lies in its specific exploration through a comprehensive analysis spanning five years, revealing the alignment between semiconductor advancements and the latest SDGs. It uncovers the significance of collaborative ecosystems involving research institutions, businesses, and governments. Through these results, our study addresses a gap in the existing literature and advances semiconductor contributions to the SDGs.

A wearable colorimetric sweat pH sensor-based smart textile for health state diagnosis

Sweat pH is an important indicator for diagnosing disease states, such as cystic fibrosis. However, conventional pH sensors are composed of large brittle mechanical parts and need additional instruments to read signals. These pH sensors have limitations for practical wearable applications. In this study, we propose wearable colorimetric sweat pH sensors based on curcumin and thermoplastic-polyurethane (C-TPU) electrospun-fibers to diagnose disease states by sweat pH monitoring. This sensor aids in pH monitoring by changing color in response to chemical structure variation from enol to di-keto form via H-atom separation. Its chemical structure variation changes the visible color due to light absorbance and reflectance changes. Furthermore, it can rapidly and sensitively detect sweat pH due to its superior permeability and wettability. By O2 plasma activation and thermal pressing, this colorimetric pH sensor can be easily attached to various fabric substrates such as swaddling and patient clothing via surface modification and mechanical interlocking of C-TPU. Furthermore, the diagnosable clothing is durable and reusable enough to neutral washing conditions due to the reversible pH colorimetric sensing performance by restoring the enol form of curcumin. This study contributes to the development of smart diagnostic clothing for cystic fibrosis patients who require continuous sweat pH monitoring.

Emulsion Nanofibres as a Composite for a Textile Touch Sensor

The combination of a nanofibre net and textile support represents an interesting composite capable of conferring various properties. Nanofibres are so thin that they can be easily damaged by human touch. In this study, we hypothesised that dyeing nanofibres with different colours from their textile supports would result in a colour difference upon their degradation, providing evidence that the composite has been touched and acting as a touch sensor. Two different methods were studied: directly inserting the dye into the polymer via electrospinning or creating a coloured liquid emulsion encapsulated by the polymer via electrospinning. Two black dyes were studied. Colour index (CI) Acid Black 194 was added directly to polyvinyl alcohol (PVA) as the polymer. Sage oil was used for CI Solvent Black 3. The nanofibre nets were conveniently electrospun on a white polyester fabric; the fabrics were then characterised by colour coordinate analysis, FTIR, and SEM. The results showed that the dyed solution in oil was encapsulated, and the black colour could only be observed when rubbed, whereas the dyed polymer showed a black colour that was removed when rubbed. Therefore, the hypothesis was confirmed, and both samples demonstrated the desired touch sensor behaviour.

An Overview of Polymer Composite Films for Antibacterial Display Coatings and Sensor Applications

The escalating presence of pathogenic microbes has spurred a heightened interest in antimicrobial polymer composites tailored for hygiene applications. These innovative composites ingeniously incorporate potent antimicrobial agents such as metals, metal oxides, and carbon derivatives. This integration equips them with the unique ability to offer robust and persistent protection against a diverse array of pathogens. By effectively countering the challenges posed by microbial contamination, these pioneering composites hold the potential to create safer environments and contribute to the advancement of public health on a substantial scale. This review discusses the recent progress of antibacterial polymer composite films with the inclusion of metals, metal oxides, and carbon derivatives, highlighting their antimicrobial activity against various pathogenic microorganisms. Furthermore, the review summarizes the recent developments in antibacterial polymer composites for display coatings, sensors, and multifunctional applications. Through a comprehensive examination of various research studies, this review aims to provide valuable insights into the design, performance, and real-time applications of these smart antimicrobial coatings for interactive devices, thus enhancing their overall user experience and safety. It concludes with an outlook on the future perspectives and challenges of antimicrobial polymer composites and their potential applications across diverse fields.

Improved Antibacterial Properties of Polylactic Acid-Based Nanofibers Loaded with ZnO-Ag Nanoparticles through Pore Engineering

In the post-epidemic era, bio-based protective fiber materials with active protective functions are of utmost importance, not only to combat the spread of pathogens but also to reduce the environmental impact of petroleum-based protective materials. Here, efficient antibacterial polylactic acid-based (PLA-based) fibers are prepared by solution blow spinning and their pore structures are regulated by controlling the ratio of the solvent components in the spinning solutions. The porous PLA-based fibers exhibit antibacterial efficiencies of over 99% against Escherichia coli and over 98% against Bacillus subtilis, which are significantly higher than that of the nonporous PLA-based fibers. The excellent antibacterial property of the porous PLA-based fibers can be attributed to their high porosity, which allows antibacterial nanoparticles to be released more easily from the fibers, thus effectively killing pathogenic microorganisms. Moreover, pore structure regulation can also enhance the mechanical property of the PLA-based fiber materials. Our approach of regulating the microstructure and properties of the PLA-based fibers through pore engineering can be extended to other polymer fiber materials and is suitable for polymer-based composite systems that require optimal performance through sufficient exposure of doped materials.

Highly active nanoparticle enhanced rapid adsorption-killing mechanism to combat multidrug-resistant bacteria

Contact-killing surfaces with the ability to rapidly adsorb and kill microorganisms are desperately needed since the rapid outbreak of multidrug-resistant (MDR) bacteria poses a serious threat to human health. Therefore, a series of amphiphilic nanoengineered polyquaterniums (ANPQs) were synthesized, and immobilizing ANPQs onto equipment surfaces provided a simple method for preventing microbial infections. The strong charge-positive property of ANPQ offered the possibility of rapid adsorption and efficient killing, such that all bacteria are adsorbed after 10 seconds of contact with ANPQ-treated fabrics, and more than 99.99% of pathogens are killed within 30 seconds. Surprisingly, the adsorption-killing mechanism made it difficult for bacteria to develop resistance to ANPQ coating, even after long-term repeated treatment. Importantly, in a Methicillin-resistant Staphylococcus aureus infection model, ANPQ-treated fabrics exhibited a potent anti-infectious performance while remaining nontoxic. It is envisaged that the strategy of using ANPQ coating undoubtedly provides a promising candidate for fighting MDR strains.

Recent Progress and Trends in the Development of Electrospun and 3D Printed Polymeric-Based Materials to Overcome Antimicrobial Resistance (AMR)

Antimicrobial resistance (AMR) developed by microorganisms is considered one of the most critical public health issues worldwide. This problem is affecting the lives of millions of people and needs to be addressed promptly. Mainly, antibiotics are the substances that contribute to AMR in various strains of bacteria and other microorganisms, leading to infectious diseases that cannot be effectively treated. To avoid the use of antibiotics and similar drugs, several approaches have gained attention in the fields of materials science and engineering as well as pharmaceutics over the past five years. Our focus lies on the design and manufacture of polymeric-based materials capable of incorporating antimicrobial agents excluding the aforementioned substances. In this sense, two of the emerging techniques for materials fabrication, namely, electrospinning and 3D printing, have gained significant attraction. In this article, we provide a summary of the most important findings that contribute to the development of antimicrobial systems using these technologies to incorporate various types of nanomaterials, organic molecules, or natural compounds with the required property. Furthermore, we discuss and consider the challenges that lie ahead in this research field for the coming years.

Biomedical equipments, vaccine and drug in the prevention, diagnosis and treatment of COVID-19

SARS-CoV-2 virus caused an infectious disease, named COVID-19. Biomedical equipments, vaccine and drug have played a crucial role in the prevention, diagnosis and treatment. Nevertheless, up to now, there still has been no literature summarizing the diagnosis, prevention and treatment of this infectious disease from the perspective of biomedical equipments. Thus, this review wants to give an overview on the biomedical equipments, vaccine and drug in the prevention, diagnosis and treatment of this disease, and avoids the overlap with previous research, more emphasis on biomedical equipments, and less emphasis on biomaterials. The existing problems in the current research and application were summarized, and the future research direction was proposed, so as to provide reference to deal with similar viral infections in the future.

Nanostructures for prevention, diagnosis, and treatment of viral respiratory infections: from influenza virus to SARS-CoV-2 variants

Viruses are a major cause of mortality and socio-economic downfall despite the plethora of biopharmaceuticals designed for their eradication. Conventional antiviral therapies are often ineffective. Live-attenuated vaccines can pose a safety risk due to the possibility of pathogen reversion, whereas inactivated viral vaccines and subunit vaccines do not generate robust and sustained immune responses. Recent studies have demonstrated the potential of strategies that combine nanotechnology concepts with the diagnosis, prevention, and treatment of viral infectious diseases. The present review provides a comprehensive introduction to the different strains of viruses involved in respiratory diseases and presents an overview of recent advances in the diagnosis and treatment of viral infections based on nanotechnology concepts and applications. Discussions in diagnostic/therapeutic nanotechnology-based approaches will be focused on H1N1 influenza, respiratory syncytial virus, human parainfluenza virus type 3 infections, as well as COVID-19 infections caused by the SARS-CoV-2 virus Delta variant and new emerging Omicron variant.

Electrospun nanofibers for medical face mask with protection capabilities against viruses: State of the art and perspective for industrial scale-up

Face masks have proven to be a useful protection from airborne viruses and bacteria, especially in the recent years pandemic outbreak when they effectively lowered the risk of infection from Coronavirus disease (COVID-19) or Omicron variants, being recognized as one of the main protective measures adopted by the World Health Organization (WHO). The need for improving the filtering efficiency performance to prevent penetration of fine particulate matter (PM), which can be potential bacteria or virus carriers, has led the research into developing new methods and techniques for face mask fabrication. In this perspective, Electrospinning has shown to be the most efficient technique to get either synthetic or natural polymers-based fibers with size down to the nanoscale providing remarkable performance in terms of both particle filtration and breathability. The aim of this Review is to give further insight into the implementation of electrospun nanofibers for the realization of the next generation of face masks, with functionalized membranes via addiction of active material to the polymer solutions that can give optimal features about antibacterial, antiviral, self-sterilization, and electrical energy storage capabilities. Furthermore, the recent advances regarding the use of renewable materials and green solvent strategies to improve the sustainability of electrospun membranes and to fabricate eco-friendly filters are here discussed, especially in view of the large-scale nanofiber production where traditional membrane manufacturing may result in a high environmental and health risk.

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.

Totally-green cellulosic fiber with prominent sustained antibacterial and antiviral properties for potential use in spunlaced non-woven fabric production

The worldwide spread of COVID-19 has put a higher requirement for personal medical protective clothing, developing protective clothing with sustained antibacterial and antiviral performance is the priority for safe and sustaining application. For this purpose, we develop a novel cellulose based material with sustained antibacterial and antiviral properties. In the proposed method, the chitosan oligosaccharide (COS) was subjected to a guanylation reaction with dicyandiamide in the presence of Scandium (III) triflate; because of the relatively lower molecular weight and water solubility of the COS, GCOS (guanylated chitosan oligosaccharide) with high substitution degree (DS) could be successfully synthetized without acid application. In this instance, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the GCOS were only 1/8 and 1/4 of that of COS. The introduction of GCOS onto the fiber endowed the fiber with extremely high antibacterial and antiviral performance, showing 100% bacteriostatic rate against Staphylococcus aureus and Escherichia coli and 99.48% virus load reduction of bacteriophage MS2. More importantly, the GCOS modified cellulosic fibers (GCOS-CFs) exhibit excellent sustained antibacterial and antiviral properties; namely, 30 washing cycles had negligible effect on the bacteriostatic rate (100%) and inhibition rate of bacteriophage MS2 (99.0%). Moreover, the paper prepared from the GCOS-CFs still exhibited prominent antibacterial and antiviral activity; inferring that the sheeting forming, press, and drying process have almost no effect on the antibacterial and antiviral performances. The insensitive of antibacterial and antiviral activity to water washing (spunlace) and heat (drying) make the GCOS-CFs a potential material applicable in the spunlaced non-woven fabric production.

Electrospinning in personal protective equipment for healthcare work

Protection in many service areas is mandatory for good performance in daily activities of workers, especially health areas. Personal protective equipment (PPE) is used to protect patients and health workers from contamination by harmful pathogens and body fluids during clinical attendance. The pandemic scenario caused by SARS-CoV-2 has shown that the world is not prepared to face global disease outbreaks, especially when it comes to the PPE of healthcare workers. In the last years, the world has faced a deficiency in the development of advanced technologies to produce high-quality PPE to attend to the exponential increasing demand. Electrospinning is a technology that can be used to produce high-quality PPE by improving the protective action of clothing. In the face of this concern, this manuscript presents as focus the potential of electrospinning to be applied in protective clothing. PPE mostly used by healthcare workers are also presented. The physico-chemical characteristics and production processes of medical textiles for PPE are addressed. Furthermore, an overview of the electrospinning technique is shown. It is important to highlight most research about electrospinning applied to PPE for health areas presents gaps and challenges; thus, future projections are also addressed in this manuscript.

Synergistic Enhancement of Filtering Efficiency and Antibacterial Performance of a Nanofiber Air Filter Decorated with Electropolarized Lithium-Doped ZnO Nanorods

According to clinical case reports, bacterial co-infection with COVID-19 can significantly increase mortality, with Staphylococcus aureus (S. aureus) being one of the most common pathogens causing complications such as pneumonia. Thus, during the pandemic, research on imparting air filters with antibacterial properties was actively initiated, and several antibacterial agents were investigated. However, air filters with inorganic nanostructures on organic nanofibers (NFs) have not been investigated extensively. This study aimed to demonstrate the efficiency of electropolarized poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) NFs decorated with Li-doped ZnO nanorods (NRs) to improve the filtering ability and antibacterial activity of the ultrathin air filter. The surfactant was loaded onto the ZnO─known for its biocompatibility and low toxicity─nanoparticles (NPs) and transferred to the outer surface of the NFs, where Li-doped ZnO NRs were grown. The Li-doped ZnO NR-decorated NF effectively enhanced the physical filtration efficiency and antibacterial properties. Additionally, by exploiting the ferroelectric properties of Li-doped ZnO NRs and PVDF-TrFE NFs, the filter was electropolarized to increase its Coulombic interaction with PMs and S. aureus. As a result, the filter exhibited a 90% PM1.0 removal efficiency and a 99.5% sterilization rate against S. aureus. The method proposed in this study provides an effective route for simultaneously improving the air filter performance and antibacterial activity.

Magnetically retrievable Fe3O4@SiO2@ZnO piezo-photocatalyst: Synthesis and multiple catalytic properties

The piezo-/photocatalytic effects of ZnO have been in the limelight because of their great potential in environmental remediation and energy conversion. However, the poor recyclability of the suspended catalysts can cause inevitable secondary pollution, which is one of the major issues that limit the practical application of these materials. To address this problem, a magnetically retrievable Fe₃O₄@SiO₂@ZnO nanocomposite was designed and successfully synthesized by multi-step reactions. The ZnO nanorods were vertically grown on the surface of the magnetic Fe₃O₄@SiO₂ microspheres, while SiO₂ served as an insulator to protect the inner core and to inhibit charge transfer across the core/shell interface. The Fe₃O₄@SiO₂@ZnO nanocomposite can be easily collected and separated by using a magnetic field. Along with the good recyclability, the material also exhibited high efficiencies in piezocatalytic, photocatalytic and piezo-photocatalytic dye degradation processes. The rate constant of piezo-photocatalysis reached 95.9 × 10^-3 min^-1, which was 2.2 and 6.1 times that of the individual piezocatalysis and photocatalysis, respectively. The present result confirmed the existence of a synergetic effect between piezo- and photocatalytic processes. Hereby, we demonstrated that incorporation of a magnetic carrier is a feasible strategy to achieve retrievable and highly efficient piezo-/photocatalyst.

Electrospun PVB/AVE NMs as mask filter layer for win-win effects of filtration and antibacterial activity

The COVID-19 pandemic has caused serious social and public health problems. In the field of personal protection, the facial masks can prevent infectious respiratory diseases, safeguard human health, and promote public safety. Herein, we focused on preparing a core filter layer for masks using electrospun polyvinyl butyral/apocynum venetum extract nanofibrous membranes (PVB/AVE NMs), with durable interception efficiency and antibacterial properties. In the spinning solution, AVE acted as a salt to improve electrical conductivity, and achieve long-lasting interception efficiency with adjustable pore size. It also played the role of an antibacterial agent in PVB/AVE NMs to achieve win-win effects. The hydrophobicity of PVB-AVE-6% was 120.9° whereas its filterability reached 98.3% when the pressure drop resistance was 142 Pa. PVB-AVE-6% exhibited intriguing properties with great antibacterial rates of 99.38% and 98.96% against S. aureus and E. coli, respectively. After a prolonged usability test of 8 h, the filtration efficiency of the PVB/AVE masks remained stable at over 97.7%. Furthermore, the antibacterial rates of the PVB/AVE masks on S. aureus and E. coli were 96.87% and 96.20% respectively, after using for 2 d. These results indicate that PVB/AVE NMs improve the protective performance of ordinary disposable masks, which has certain application in air filtration.

Advanced and Smart Textiles during and after the COVID-19 Pandemic: Issues, Challenges, and Innovations

The COVID-19 pandemic has hugely affected the textile and apparel industry. Besides the negative impact due to supply chain disruptions, drop in demand, liquidity problems, and overstocking, this pandemic was found to be a window of opportunity since it accelerated the ongoing digitalization trends and the use of functional materials in the textile industry. This review paper covers the development of smart and advanced textiles that emerged as a response to the outbreak of SARS-CoV-2. We extensively cover the advancements in developing smart textiles that enable monitoring and sensing through electrospun nanofibers and nanogenerators. Additionally, we focus on improving medical textiles mainly through enhanced antiviral capabilities, which play a crucial role in pandemic prevention, protection, and control. We summarize the challenges that arise from personal protective equipment (PPE) disposal and finally give an overview of new smart textile-based products that emerged in the markets related to the control and spread reduction of SARS-CoV-2.

Cellular uptake of metal oxide-based nanocomposites and targeting of chikungunya virus replication protein nsP3

Emergence of new pathogenic viruses along with adaptive potential of RNA viruses has become a major public health concern. Therefore, it is increasingly crucial to investigate and assess the antiviral potential of nanocomposites, which is constantly advancing area of medical biology. In this study, two types of nanocomposites: Ag/NiO and Ag₂O/NiO/ZnO with varying molar ratios of silver and silver oxide, respectively have been synthesised and characterised. Three metal/metal oxide (Ag/NiO) composites having different amounts of Ag nanoparticles (NPs) anchored on NiO octahedrons are AN-5 % (5 % Ag), AN-10 % (10 % Ag) and AN-15 % (15 % Ag)) and three ternary metal oxide nanocomposites (Ag₂O/NiO/ZnO) i.e., A/N/Z-1, A/N/Z-2, and A/N/Z-3 with different molar ratios of silver oxide (10 %, 20 % and 30 %, respectively) were evaluated for their antiviral potential. Cellular uptake of nanocomposites was confirmed by ICP-MS. Intriguingly, molecular docking of metal oxides in the active site of nsP3 validated the binding of nanocomposites to chikungunya virus replication protein nsP3. In vitro antiviral potential of nanocomposites was tested by performing plaque reduction assay, cytopathic effect (CPE) analysis and qRT-PCR. The nanocomposites showed significant reduction in virus titre. Half-maximal inhibitory concentration (IC₅₀) for A/N/Z-3 and AN-5 % were determined to be 2.828 and 3.277 µg/mL, respectively. CPE observation and qRT-PCR results were consistent with the data obtained from plaque reduction assay for A/N/Z-3 and AN-5 %. These results have opened new avenues for development of nanocomposites based antiviral therapies.

Antibacterial and antiviral chitosan oligosaccharide modified cellulosic fibers with durability against washing and long-acting activity

The worldwide outbreak of SARS-CoV-2 has attracted extensive attention to antibacterial and antivirus materials. Cellulose is the most potential candidate for the preparation of green, environmentally friendly antibacterial and antiviral materials. Herein, modified cellulosic fibers with sustained antibacterial and antiviral performance was prepared by introducing chitosan oligosaccharide onto the fibers. The two-step method is proved to be more effective than the one-step method for enhanced chitosan oligosaccharide loadings and antibacterial and antiviral activity. In this instance, the modified fibers with 61.77 mg/g chitosan oligosaccharide loadings can inhibit Staphylococcus aureus and Escherichia coli by 100 % after contacting with bacteria for 12 h and reduce the bacteriophage MS2 by 99.19 % after 1 h of contact. More importantly, the modified fibers have washing durable antibacterial and antiviral activity; the modified fibers have 100 % antibacterial and 98.38 % antiviral activity after 20 washing cycles. Benefiting from the excellent performance of the individual fibers, the paper prepared from the modified fibers show great antibacterial (100 %) and antiviral performance (99.01 %) and comparable mechanical strength. The modified fibers have potential applications in the manufacture of protective clothing and protective hygiene products.

Disintegration and Machine-Learning-Assisted Identification of Bacteria on Antimicrobial and Plasmonic Ag-CuxO Nanostructures

Bacteria cause many common infections and are the culprit of many outbreaks throughout history that have led to the loss of millions of lives. Contamination of inanimate surfaces in clinics, the food chain, and the environment poses a significant threat to humanity, with the increase in antimicrobial resistance exacerbating the issue. Two key strategies to address this issue are antibacterial coatings and effective detection of bacterial contamination. In this study, we present the formation of antimicrobial and plasmonic surfaces based on Ag-CuxO nanostructures using green synthesis methods and low-cost paper substrates. The fabricated nanostructured surfaces exhibit excellent bactericidal efficiency and high surface-enhanced Raman scattering (SERS) activity. The CuxO ensures outstanding and rapid antibacterial activity within 30 min, with a rate of >99.99% against typical Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. The plasmonic Ag nanoparticles facilitate the electromagnetic enhancement of Raman scattering and enables rapid, label-free, and sensitive identification of bacteria at a concentration as low as 103 cfu/mL. The detection of different strains at this low concentration is attributed to the leaching of the intracellular components of the bacteria caused by the nanostructures. Additionally, SERS is coupled with machine learning algorithms for the automated identification of bacteria with an accuracy that exceeds 96%. The proposed strategy achieves effective prevention of bacterial contamination and accurate identification of the bacteria on the same material platform by using sustainable and low-cost materials.

Silver Nanoparticles: Review of Antiviral Properties, Mechanism of Action and Applications

New antiviral drugs and new preventive antiviral strategies are a target of intense scientific interest. Thanks to their peculiar properties, nanomaterials play an important role in this field, and, in particular, among metallic materials, silver nanoparticles were demonstrated to be effective against a wide range of viruses, in addition to having a strong antibacterial effect. Although the mechanism of antiviral action is not completely clarified, silver nanoparticles can directly act on viruses, and on their first steps of interaction with the host cell, depending on several factors, such as size, shape, functionalization and concentration. This review provides an overview of the antiviral properties of silver nanoparticles, along with their demonstrated mechanisms of action and factors mainly influencing their properties. In addition, the fields of potential application are analyzed, demonstrating the versatility of silver nanoparticles, which can be involved in several devices and applications, including biomedical applications, considering both human and animal health, environmental applications, such as air filtration and water treatment, and for food and textile industry purposes. For each application, the study level of the device is indicated, if it is either a laboratory study or a commercial product.