ساخت فیلتر نانو جدید برای جلوگیری از گسترش ویروس کرونا در هوا

محققان با استفاده از نانورشته‌های پلیمری فیلتر نانو جدیدی را ساختند که قادر است ۹۹.۹ درصد از ذرات معلق حاوی ویروس کرونا را جذب کند.

به گزارش ایرنا از پایگاه خبری ساینس، محققان دانشگاه کالیفرنیا ریورساید واقع در آمریکا برای ساخت این فیلتر، یک ولتاژ الکتریکی بالا را از درون یک قطره پلی وینیلیدین فلوراید عبور دادند تا نانوالیافی با قطر ۳۰۰ نانومتر تشکیل شود. این فرایند منافذی به قطر چند میکرومتر روی سطح نانوالیاف ایجاد کرده است که باعث جذب ۹۹.۹ درصد از ذرات معلق حاوی ویروس کرونا می‌شود.

این تکنیک ساخت که با عنوان الکتروریسی شناخته می‌شود، یک شیوه مقرون به صرفه است که امکان تولید انبوه فیلترهای نانوفیبر را برای ساخت تجهیزات محافظت شخصی و سیستم‌های فیلترسازی فراهم می‌کند.

ویروس کرونا عامل بیماری کووید ۱۹ از اواخر سال ۲۰۱۹ در شهر ووهان چین مشاهده و در مدت کوتاهی در همه جهان منتشر شد؛ به طوری که سازمان بهداشت جهانی در اسفند ۹۸ (فوریه ۲۰۲۰) بروز پاندمی (همه‌گیری جهانی) این بیماری را تأیید کرد.

ویروس کرونا با دست آلوده یا عطسه، سرفه و حتی قطرات تنفسی از طریق دهان، بینی و چشم به افراد منتقل می‌شود. تنگی نفس، خستگی و بدن درد، اختلال در بویایی و چشایی و مشکلات گوارشی از جمله علائم بیماری کووید ۱۹ است. بیش از ۸۰ درصد مبتلایان به ویروس نیز دچار بیماری خفیف می‌شوند.

جهش ویروس کرونا در انگلیس، بزریل، هندوستان و آفریقا که موجب افزایش سرایت، بیماری‌زایی و مرگ و میر آن شده، نگرانی‌های جدیدی را در جهان به وجود آورده است.

گزارش کامل این تحقیقات در نشریه Environmental Science & Technology Letters منتشر شده است.

Abstract

Airborne transmission of SARS-CoV-2 plays a critical role in spreading COVID-19. To protect public health, we designed and fabricated electrospun nanofibrous air filters that hold promise for applications in personal protective equipment (PPE) and the indoor environment. Due to ultrafine nanofibers (∼300 nm), the electrospun air filters had a much smaller pore size in comparison to the surgical mask and cloth masks (a couple of micrometers versus tens to hundreds of micrometers). A coronavirus strain served as a SARS-CoV-2 surrogate and was used to generate aerosols for filtration efficiency tests, which can better represent SARS-CoV-2 in comparison to other agents used for aerosol generation in previous studies. The electrospun air filters showed excellent performance by capturing up to 99.9% of coronavirus aerosols, which outperformed many commercial face masks. In addition, we observed that the same electrospun air filter or face mask removed NaCl aerosols equivalently or less effectively in comparison to the coronavirus aerosols when both aerosols were generated from the same system. Our work paves a new avenue for advancing air filtration by developing electrospun nanofibrous air filters for controlling SARS-CoV-2 airborne transmission

Introduction

The ongoing COVID-19 pandemic has raised serious public health concerns. More evidences have highlighted the importance of the airborne transmission of SARS-CoV-2, the causative agent of COVID-19. 1 2 Aerosols (< 5 μm) can suspend in the air for a long duration, accumulate in a closed environment, remain infectious (the half-life of SARS-CoV-2 in aerosols is 1.1 h), 3 and thus involve in the long-range transmission of airborne diseases. Therefore, there is an urgent need to control the airborne transmission of SARS-CoV-2.

One accepted strategy to control the airborne transmission of SARS-CoV-2 is to wear face masks and respirators as personal protective equipment (PPE). However, cloth masks do not always have satisfactory aerosol removal efficiency, droplet repulsion, and/or breathability. 4 SARS-CoV-2 in the indoor environment can also potentially spread through heating, ventilation, and air conditioning (HVAC) systems, 5 and effective air filtration is promising to control the spread of airborne diseases. However, most air filters used in residential, commercial, and industrial buildings (minimum efficiency reporting value (MERV) <13) other than high-efficiency particulate air (HEPA) filters used in healthcare facilities only capture larger particles like dusts, mold spores, or bacteria but not airborne viruses. 6 Nanotechnology holds promise for developing effective, scalable, and affordable air filters for both mask/respirator and HVAC system applications.

Electrospinning has emerged as a new technology to synthesize non-woven nanofibrous membranes that are ideal for air filtration. 7–11 During electrospinning, a polymer solution is ejected into a strong electric field to form fine nanofibers. Electrospun air filters have a reduced pore size (submicrometers to several micrometers) than conventional filters, which enable effective capture of small airborne particles. The large porosity of electrospun air filters can also reduce air pressure drop in filtration as well as enhance the breathability of masks/respirators. 12 More importantly, electrospinning is operated under a strong electric field (i.e., 1-5 kV cm-1), and it produces filters with retained surface and volume charges that can last for weeks or even months. The presence of the retained charges can significantly promote aerosol capture through electrostatic attraction. 13 Electrospun nanofibrous membranes have shown excellent performance for removing aerosols generated from polystyrene beads, NaCl, and bacteria (e.g., Staphylococcus epidermidis, Staphylococcus aureus). 12, 14–18

To date, many studies have evaluated the filtration efficiency of air filters and face masks by using surrogate aerosols instead of coronavirus aerosols. 12, 14–20 However, it remains elusive whether the reported filtration performance can be used to understand coronavirus control because of distinct properties between the surrogate and coronavirus. Moreover, developing electrospun air filters for capturing viral aerosols is still at its nascent stage and no report is available yet. In this work, we systematically compared the filtration efficiency of coronavirus and NaCl aerosols for a broad spectrum of electrospun air filters and face masks, and concluded that NaCl is an eligible surrogate for coronavirus during aerosol filtration tests for the first time. Murine hepatitis virus A59 (MHV-A59), a β-coronavirus in the same family as SARS-CoV-2, was selected for aerosol generation and filtration. In addition, we developed advanced electrospun air filters for capturing coronavirus aerosols that outperformed many commercially available face masks.

https://pubs.acs.org/doi/full/10.1021/acs.estlett.1c00337