# Antiviral Filtering Capacity of GO-Coated Textiles
## 1 Introduction  
Pathogenic microorganisms, such as viruses in the environment, use different routes to bring about infection and cause disease that may seriously compromise public health; the SARS-CoV2 virus, for example, can be easily transmitted through droplets or aerosol and can be inhaled or deposited on the surface of objects with which people may come into contact. New solutions are therefore needed to protect people from inhaling viral agents or to disinfect surfaces better. Nanomaterials are useful in the fight against viral infection. Carbon-based nanomaterials in particular, by virtue of their low cytotoxicity, high biocompatibility, and wide spectrum of applications, are important as virucidal substances and for preventing infection. Graphene derivatives have been shown to have antibacterial activity in a number of ways [1]; for example, the authors have recently demonstrated that GO disrupted the bacterial wall and induced oxidative stress in a dose-dependent mode [2]. Although researchers are interested in knowing the antiviral properties of GO, there are still few studies that report its direct antiviral effects. Some reports demonstrate thatGO's negative charges may disrupt viral envelope proteins [3]. According to these authors, the physical interaction of the viruses with GO's sharp edges is at the origin of the antiviral activity [4]. The impact of the charge on GO anti-viral function seems to be related to the link with ionic and/or nonionic polymers [5]. In particular, the interaction of GO functionalized with ionic polyglycerol sulfate and/or fatty amine functionalities platform with Herpes Simplex Virus type 1 (HSV-1) has been widely studied, where the HSV-1 is a virus model system similar to the one used in this study. The combination of sulfate and alkyl chains produces binding of the virus through electrostatic interaction with the polyglycerol sulfate (ionic polymer), while the alkyls (the non-ionic counterpart of polymers) induce a high level of antiviral activity through secondary hydrophobic interaction. Longer alkyl chains exhibited the highest level of antiviral activity, but they are also toxic against Vero cells [6]. For GO functionalization aimed at virus inhibition, it is, therefore, best to use polymers with C6 and C9 as hydrocarburic alkyl chains. Nanoparticle size and shape both have a significant impact on inhibitory efficiency. Regarding size, a higher inhibitory effect has mainly been observed in the presence of the small GO sheets, when compared to medium and large GO nanosheets [7]. This effect can be explained considering both aspects, as the bending and the cooperative encapsulation. Regarding shape, some authors report [8] that virus destruction and deactivation mainly occur only in the presence of negatively charged sharp-edged GO nanosheets. [PERSON] et al. [8] report about the antiviral activity of GO against two different viruses, showing that low non-cytotoxic concentrations of GO suppress infection of target cells by deactivating the virus particles prior to entry into the cell. The same authors also analyzed GO structure and concluded that nanosheets were able to inactivate both viruses by structural destruction before entry into cells. The shape parameter of nanomaterials is also taken into consideration in other studies because different antiviral effects have been observed when the nanomaterial shape changes from nanosheets to spherical nanoparticles. As shown with gold nanoparticles, different phases of viral infection can be inhibited by nanoparticles [9]. The application of gold nanoparticles derivatized with mercaptoethanesulfonate (AuMES NPs) as effective inhibitors of Herpes simplex virus type 1 infection based on their ability to mimic cell-surface-receptor heparan sulfate has been fully described. Several characterization studies have shown that Au-MES NPs interfere with viral bonding/interaction, entry, and cell-to-cell spread, preventing subsequent viral infection in different ways.