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.

Preparation of hydroxypropyl starch/polyvinyl alcohol composite nanofibers films and improvement of hydrophobic properties

Starch-derived edible films have great potential as biodegradable food packaging and biomedical materials, in this study, we adopted a green method to prepare starch-based composite electrospun nanofibers films. The hydroxypropyl starches (HPS) were prepared to improve native starch solubility and properties, and a series of blend solutions were prepared with different HPS/polyvinyl alcohol (PVA) weight ratios. The comparison of the properties of HPS/PVA (HPA) nanofibers with different amylose contents were evaluated, and the fibers fabricated from hydroxypropyl high amylose starch (HP-HAS) had more continuous and homogeneous morphologies compared to the other starch fibers, it was also found that the addition of HP-HAS in the film has better mechanical properties than pure PVA film. Thus, to improve the hydrophobicity of the film, the HP-HAS/PVA (HPA(H)) nanofiber was selected for the hydrophobic study by the citric acid (CA) treatment. The hydrophobic surface was formed on the HPA(H) film by CA self-assembled coating with a water contact angle changed from 30.95° up to 100.74°. This study successfully prepared the modified starch/PVA composite nanofibers and established a simple method of self-assembled hydrophobic modification to improve water stability. Therefore, this green strategy is an alternative candidate in further study for food packaging and relative areas.

Electrospun-Based Membranes as a Key Tool to Prevent Respiratory Infections

The use of electrospun meshes has been proposed as highly efficient protective equipment to prevent respiratory infections. Those infections can result from the activity of micro-organisms and other small dust particles, such as those resulting from air pollution, that impair the respiratory tract, induce cellular damage and compromise breathing capacity. Therefore, electrospun meshes can contribute to promoting air-breathing quality and controlling the spread of such epidemic-disrupting agents due to their intrinsic characteristics, namely, low pore size, and high porosity and surface area. In this review, the mechanisms behind the pathogenesis of several stressors of the respiratory system are covered as well as the strategies adopted to inhibit their action. The main goal is to discuss the performance of antimicrobial electrospun nanofibers by comparing the results already reported in the literature. Further, the main aspects of the certification of filtering systems are highlighted, and the expected technology developments in the industry are also discussed.

Biodegradable, biomimetic, and nanonet-engineered membranes enable high-flux and highly-efficient oil/water separation

Porous membranes with fascinating super-wettable surface and tunable porous architecture for oil-water separation have been developed rapidly, however, the serious secondary marine pollution caused by the non-degradable defectiveness of membranes themselves is still a thorny problem. Herein, we create an eco-friendly membrane with biomimetic cobweb-like nanostructure via assembling two-dimensional bacterial cellulose nanonets on the starch nanofibrous membrane on a large scale. The obtained novel composite membranes exhibit integrated properties of sub-micron pore size, ultrahigh porosity, superhydrophilicity, and underwater superoleophobicity, stemming from the synergistic effect of the hydrated nanonet-skin-layer and porous starch matrix. By virtue of the narrow-distributed sub-micron pores, ultrahigh porosity, and ultrathin thickness, the resulting membrane shows outstanding performance of excellent separation efficiency (up to 99.996%), high percolation flux (maximum of 15968 L m^-2 h^-1), well surpassing the conventional microfiltration membranes. More significantly, with the advantage of biodegradability and anti-oil-fouling property, the membrane could serve as the robust platform for long-term wastewater remediation.

Review on Spinning of Biopolymer Fibers from Starch

Increasing interest in bio-based polymers and fibers has led to the development of several alternatives to conventional plastics and fibers made of these materials. Biopolymer fibers can be made from renewable, environmentally friendly resources and can be fully biodegradable. Biogenic resources with a high content of carbohydrates such as starch-containing plants have huge potentials to substitute conventional synthetic plastics in a number of applications. Much literature is available on the production and modification of starch-based fibers and blends of starch with other polymers. Chemistry and structure–property relationships of starch show that it can be used as an attractive source of raw material which can be exploited for conversion into a number of high-value bio-based products. In this review, possible spinning techniques for the development of virgin starch or starch/polymer blend fibers and their products are discussed. Beneficiation of starch for the development of bio-based fibers can result in the sustainable replacement of oil-based high-value materials with cost-effective, environmentally friendly, and abundant products.

Recent Trends in the Fabrication of Starch Nanofibers: Electrospinning and Non-electrospinning Routes and Their Applications in Biotechnology

Electrospinning a versatile and the most preferred technique for the fabrication of nanofibers has revolutionized by opening unlimited avenues in biomedical fields. Presently, the simultaneous functionalization and/or post-modification of as-spun nanofibers with biomolecules has been explored, to serve the distinct goals in the aforementioned field. Starch is one of the most abundant biopolymers on the earth. Besides, being biocompatible and biodegradable in nature, it has unprecedented properties of gelatinization and retrogradation. Therefore, starch has been used in numerous ways for wide range of applications. Keeping these properties in consideration, the present article summarizes the recent expansion in the fabrication of the pristine/modified starch-based composite scaffolds by electrospinning along with their possible applications. Apart from electrospinning technique, this review will also provide the comprehensive information on various other techniques employed in the fabrication of the starch-based nanofibers. Furthermore, we conclude with the challenges to be overcome in the fabrication of nanofibers by the electrospinning technique and future prospects of starch-based fabricated scaffolds for exploration of its applications.