# Antiviral Filtering Capacity of GO-Coated Textiles
## 3 Results  
### Characterization of GO Nano Sheets  
GO nanosheet characterization is shown in Table 1 and Figures 1 and 2.  
Figure 1A,B show the morphology of GO nanosheets, while their area and thickness have been quantified by AFM, reported in Table 1.  
The functionalization of GO was highlighted by the Raman study, shown in Figure 1C, where the presence of a more intense D band compared to the one exhibited by the graphite sample and the highest \(\rm I_{D}/I_{G}\) ratio confirmed the presence of oxygenated functionalities on the GO surface, edge and sides. The FTIR study (Figure 1D) shows the different functional groups in graphite and GO samples. The peak centered at 3413 cm\({}^{-1}\) is mainly due to the O-H stretching modes that combined with the signal recorded at 1722 cm\({}^{-1}\) (mainly related to the C(=O) stretching modes) reveals the functionalization of GO, mainly by the anchored carboxylic groups (i.e., C(=O)-OH). Absorption bands around 2355 cm\({}^{-1}\) represented the symmetric and asymmetric C-H stretching modes, while the signals recorded at 1618 and 1076 cm\({}^{-1}\) are representative of C=C groups from unoxidized sp\({}^{2}\) C=C bonds of graphite stretching vibration modes and C-O vibrations of GO sample respectively [16; 17]. The FTIR investigation highlights the formation of GO and its hygroscopic features due to the presence of oxygenated functional groups. The FTIR results were confirmed by XPS characterization reported in Table 1 and published in our previous paper [18].  
The oxygenated functional groups on GO samples have been also investigated by Z-potential measurements, reported in Table 2. As shown in Table 2, the GO appears as a negatively charged material (due to carboxylates groups, C=(O)-OH), while viral capsule alone was positively charged. Conjugation of GO and HHV-6A resulted in a more positively charged GO/HHV-6A new composite material.  
The XRD spectrum (Figure 2A) shows both profiles for GO and Graphite. The dry GO and Graphite powders were directly used in the X-ray diffraction (XRD) analysis. The XRD measurement shows that the (002) diffraction peak of Graphite (Figure 2A appears at ca. 26.6\({}^{\circ}\), and the interlay space is ca. 0.34 nm. After oxidation, the interlay space of GO  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Samples** & **Z-Potential** \\  & \(\zeta\) **(mV)** \\ \hline GO & \(-\)40.5 \(\pm\) 0.2 \\ human herpesvirus 6A (HHV-6A) & +18.7 \(\pm\) 0.5 \\ GO/6A (HHV-6A) conjugation & +16.9 \(\pm\) 1.0 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Z-potential of the functionalized GO, the human herpesvirus 6A (HHV-6A), and the subsequent conjugation with the GO.  
Figure 2: (**A**): XRD profiles of Graphite (a) and GO (b); (**B**): TGA curves for GO (pink curve line) and graphite (black curve line).  
(11.8\({}^{\circ}\), 0.75 nm, Figure 2B is larger than that of the pure graphite as a consequence of the introduction of oxygenated functional groups on carbon sheets.  
TGA performed on natural graphite and GO heated to 900\({}^{\circ}\) C at a heating rate of 5 \({}^{\circ}\)C min\({}^{-1}\) under N\({}_{2}\), evidenced that GO is thermally unstable and starts to lose mass when heated even below 100 \({}^{\circ}\)C, and there are two significant drops in mass at around 226 \({}^{\circ}\)C and 541 \({}^{\circ}\)C, respectively. The above drops in mass are due to the decomposition of the labile oxygen-containing functional groups, yielding CO, CO\({}_{2}\), and steam. The final part of the TGA curve, starting from 600 \({}^{\circ}\)C up to 1000 \({}^{\circ}\)C, is related to the pyrolysis of the GO carbon (C sp\({}^{2}\)) skeleton. The natural graphite shows a typical TGA profile, where at 800 \({}^{\circ}\)C, the carbon-based materials pyrolysis event, significantly occurs. Regarding the natural graphite TGA profile, the only significant mass loss appears at around 800 \({}^{\circ}\)C, related to pyrolysis.