## 4 Conclusions  
Graphene oxide was successfully synthesized using the modified Hummers' method. The GO was then coated with different concentrations of Zn (OH)x to study the effect of Zn (OH)x coating on the antibacterial activity of GO against Gram-positive _B. megaterium_ and Gram-negative _E. coli_ bacteria. The GO/Zn (OH)x nanocomposites were characterized using different methods. The GO/Zn (OH)x composites exhibited a hybrid stacked sheet structure with some agglomerations of Zn (OH)x on the surface. The XRD and XPS analysis effectively confirmed the presence of Zn (OH)x in the GO/Zn (OH)x nanocomposites. The antibacterial results showed inhibition on both Gram-negative _E. coli_ and Gram-positive _B. megaterium_. However, the GO/Zn (OH)x nanocomposite had larger inhibition zones against the Gram-positive _B. megaterium_. There was also a significant increase in the inhibition zone with increasing the amount of Zn (OH)x coating against the Gram-positive bacteria. The same positive trend was observed against the Gram-negative bacteria. Although there was an increase in the inhibition zone, it was not as significant as the increase for the Gram-positive bacteria case. Zinc hydroxide has been observed to perform better against Gram-positive bacteria, and the results further confirmed that behavior.  
Figure 12: Relationship between Zn (OH)x coating concentration on GO and their inhibition zone diameters.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{_B. megaterium_} & \multicolumn{2}{c}{_E. coli_} \\ \hline
**\% Coating** & **Zone of Inhibition** & **Standard Deviation** & **Zone of Inhibition** & **Standard Deviation** \\ \hline
0 & 1.9277 & 0.118541 & 1.3372 & 0.066645 \\ \hline
25 & 2.6266 & 0.08994 & 1.8097 & 0.048761 \\ \hline
50 & 2.9097 & 0.069652 & 1.9962 & 0.057996 \\ \hline
75 & 4.8273 & 0.127387 & 2.4175 & 0.08373 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Zone of Inhibition of various GO/Zn (OH)x composite NPs.  
**Author Contributions:** Conceptualization, M.A. and J.G.P.; Methodology, M.A. and J.A.S.; Formal Analysis, J.A.S., J.G.P., L.M. and M.A.; Investigation, J.A.S., L.M. and M.A.; Resources, M.A., L.M. and J.G.P.; Data Curation, M.A. and J.G.P.; Writing--Original Draft Preparation, J.A.S.; Writing--Review & Editing, M.A. and J.G.P.; Supervision, J.G.P. and M.A.; Project Administration, M.A.; Funding Acquisition, J.G.P. and M.A. All authors have read and agreed to the published version of the manuscript.  
**Funding:** [PERSON] acknowledges funding from NSF PREM (DMR-2122178), Partnership for Fostering Innovation by Bridging Excellence in Research and Student Success. [PERSON] also acknowledges the funding from the [PERSON], Jr. Endowed Chair in Engineering endowment at UTRGV. [PERSON] acknowledge and are grateful for the support provided by the UTRGV Chemistry Departmental Welch Foundation Grant (Grant No. BX-0048).  
**Institutional Review Board Statement:** This study did not require ethical approval.  
**Informed Consent Statement:** This study did not involve humans.  
**Data Availability Statement:** All the relevant data that support the findings of this study are available from the corresponding author on reasonable request.  
**Acknowledgments:** This work was supported by the [PERSON], [PERSON]. Endowed Chair in Engineering endowment at UTRGV. This work was also supported by the National Science Foundation (NSF) PREM award under grant no. DMR-2122178: UTRGV-UMN Partnership for Fostering Innovation by Bridging Excellence in Research and Student Success. [PERSON] acknowledges and is grateful for the support provided by funding from the UTRGV Chemistry Departmental Welch Foundation Grant (Grant No. BX-0048).  
**Conflicts of Interest:** The authors declare no conflict of interest.