Electrospun Nanofibrous Membranes for Controlling Airborne Viruses: Present Status, Standardization of Aerosol Filtration Tests, and Future Development

Abstract

The global COVID-19 pandemic has raised great public concern about the airborne transmission of viral pathogens. Virus-laden aerosols with small size could be suspended in the air for a long duration and remain infectious. Among a series of measures implemented to mitigate the airborne spread of infectious diseases, filtration by face masks, respirators, and air filters is a potent nonpharmacologic intervention. Compared with conventional air filtration media, nanofibrous membranes fabricated via electrospinning are promising candidates for controlling airborne viruses due to their desired characteristics, i.e., a reduced pore size (submicrometers to several micrometers), a larger specific surface area and porosity, and retained surface and volume charges. So far, a wide variety of electrospun nanofibrous membranes have been developed for aerosol filtration, and they have shown excellent filtration performance. However, current studies using electrospinning for controlling airborne viruses vary significantly in the practice of aerosol filtration tests, including setup configurations and operations. The discrepancy among various studies makes it difficult, if not impossible, to compare filtration performance. Therefore, there is a pressing need to establish a standardized protocol for evaluating the electrospun nanofibrous membranes’ performance for removing viral aerosols. In this perspective, we first reviewed the properties and performance of diverse filter media, including electrospun nanofibrous membranes, for removing viral aerosols. Next, aerosol filtration protocols for electrospun nanofibrous membranes were discussed with respect to the aerosol generation, filtration, collection, and detection. Thereafter, standardizing the aerosol filtration test system for electrospun nanofibrous membranes was proposed. In the end, the future advancement of electrospun nanofibrous membranes for enhanced air filtration was discussed. This perspective provides a comprehensive understanding of status and challenges of electrospinning for air filtration, and it sheds light on future nanomaterial and protocol development for controlling airborne viruses, preventing the spread of infectious diseases, and beyond.

Application of Electrospun Water-Soluble Synthetic Polymers for Multifunctional Air Filters and Face Masks

“…The relative humidity in exhaled breath was also found to vary depending on environmental and subject factors [85]. In addition, air humidity was found to significantly influence the aerosol filtration performance in terms of changes in filtration efficiency and pressure drop, depending on the hygroscopicity and size of the aerosol particles and the hydrophilicity of the filter media [86]. Finally, as already stated in the introduction, moisture is also a critical factor affecting the duration of electret meltblown nonwoven filters.…”

Recent advances and future perspectives in engineering biodegradable face masks

“…68 In response, electrospinning has been recognised in recent years as a versatile and feasible process for producing membranes with nanoscale diameters, decreased pore size, greater specic surface area, and porosity, allowing for high aerosol ltering efficiency and low pressure drop. 68,69 However, despite the promising characteristics, the uptake of electrospinning by the face mask industry is still limited due to the higher infrastructure and production costs, challenges in the manufacturing (ex: use of solvents) and turning of electrospun nanobers into physical products. 70 To develop face masks with high ltration efficiency, it is vital to have synergistic properties of small pore size and high porosity, high surface area, good mechanical toughness and strength.…”

“…75,138,227 However, since electrospinning is a solvent-based method, it is inevitable to apply organic solvents like N , N -dimethylformamide (DMF) for electrospinning which are volatile and hazardous. 69,228 Also, some of the biopolymers are completely insoluble in organic solvents and others, like collagen, can be irreversibly damaged as their structure can be permanently denatured resulting in a much lower level of applicability than originally expected. 229 It is critical to developing green electrospinning techniques, such as utilizing non-hazardous solvents or enhancing machinery performance to cut back on dangerous gas emissions.…”

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

“…In addition to filtration efficiency, the overall layers constituting either a surgical mask or a facepiece respirator must be both comfortable and breathable for the users. Indeed, the fabric fibers used to make a mask have to provide an effective barrier against airborne particles, but they also must ensure the person to breath properly [ 39 , 58 , [62] , [63] , [64] ]. The pressure drop is the most commonly used parameter to quantify a mask breathability, being an index of the air flow resistance of the filter for a specific material surface, which makes it a suitable indicator to assess the filter performance.…”