# Polyacrylonitrile Nanofibers Containing Viroblock as Promising Material for Protective Clothing
## 1 Introduction  
The outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-COV-2 or COVID-19) in Wuhan in 2019 is a global health emergency with many cases of death and huge economic losses [1]. The worldwide health crisis has affected all sectors of life and spread at a rapid pace. An unprecedented challenge is upon the scientific world to find effective medical treatments for the disease. COVID-19 infections are transmitted mainly through the inhalation of droplets produced by coughing and sneezing [2]. The droplets of variable sizes are dispersed through the air or rest on varied material surfaces. Droplets more than 20 \(\upmu\)m easily fall onto objects, and viruses from these droplets have been reported to last anywhere from a few hours up to several days on plastic, glass, stainless steel, cardboard, and clothing surfaces. Smaller droplets of less than 10 \(\upmu\)m arecapable of airborne transmission; particularly, droplets less than 1 \(\upmu\)m can linger in the air for more than 12 h [3]. Recent research suggested that the airborne transmission of COVID-19 is the primary propagating route, similar to previous SARS-CoV1. Before a vaccine is commonly accessed, wearing facial masks as a safety procedure is recommended by health organizations and governments to curb the rapid spread of the COVID-19 disease [4]. Nanofibrous membranes can be used as an effective protective layer against the coronavirus disease due to tiny pore sizes and high air permeability. Micro- and nanofiber masks have been developed recently with reusable, particle filtering, and antiviral properties by immobilizing antivirus agents [5]. With suitable polymer materials and disinfectants, masks can have recyclable properties and can prevent transmission of aerosol droplets with microbes after several washing cycles. Thus, exploiting active compounds and infusing them into nanofibrous masks are an efficient virus inactivation system [6]. Recently, electrospun nanofibers have been a hot topic due to their versatility and straightforwardness [7]. Productivity has largely increased in several countries including Japan, China, the USA, and Korea with the applications of multi-nozzles and other techniques [8]. The nanofibers have a wide range of morphologies and diameters, from micro- to nanometer; particularly, random orientation and porosity have the potential to capture the virus. Moreover, controllable pore size gives easy passing for water vapors. The characteristics of electrospun membranes are a high surface area, controllable porosity, and pore size [9]. Thus, the applications have been exploited in varied fields including water and air filters, tissue engineering, medical machines, environmental engineering, drug delivery, and energy storage [10]. A nanofiber-based filter with excellent capture efficiency and high blocking ability against fine dust, bacteria, and viruses shows promise in mass-produced face masks [11; 12]. Polyacrylonitrile (PAN) nanofibers obtain advantages of spinnability and excellent mechanical properties. PAN nanofibers have been used extensively for various applications such as filtration and carbon fiber mass-production [13]. PAN-based carbon fibers account for 90% of all worldwide production [14]. Nanoscale PAN membranes can be used for mask applications with easily tuned pore size, porosity, and hydrophilicity. PAN also exhibits particularly good thermal stability, solvent resistance, and good mechanical properties, and has been employed for carrying bioactive agents for antibacterial applications. PAN electrospun nanofibers, in the range of a few hundred nanometers, are promising air filters with breathable properties and filterability against viruses and fine particles [15]. Viroblock is a combination of aliphatic lipidic chains and particular cyclodext, which can deplete the cholesterol present in viral membranes. The silver penetration then inhibits the viral replication and kills bacteria and viruses.