## 3 Results and Discussion
### Biological Assessments
#### 3.3.2 Antibacterial Activity  
An antibacterial bioassay of biosynthesized metallic/bimetallic oxide nanoparticles via _Beta vulgaris_ extract was conducted against Gram-positive (_E. faecalis_ ATTC 29212 and _S. aureus_ ATTC 25923) and Gram-negative (_E. coli_ ATTC 8739 and _S. enterica_ ATTC 14028) human pathogens. The agar diffusion method was applied at 100 ug/mL. Generally, all tested nanoparticles showed antibacterial activity to various degrees. However, the Ag-SeO\({}_{2}\) bmNPs had superiority compared to the other ones, followed by the Ag-TiO\({}_{2}\) NPs (Table 2 and Figure S1). The Gram-positive bacteria were more sensitive to the tested nanoparticles than the Gram-negative ones. Among bacteria, _S. aureus_ is greatly affected by nanoparticles, especially the Ag-SeO\({}_{2}\) bmNPs followed by _E. faecalis_ and _S. enterica_. On the other hand, _E. coli_ was shown to be less susceptible to the tested nanoparticles, except for the Ag-NPs, which showed more potentiality than the other ones.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Material** & **Total Antioxidant Capacity (mg AAE/100 gm DS)****(a)** \\ \hline
**Plant extract** & 2388.524 \(\pm\) 7.226 \\ \hline
**Ag-mNPs** & 1326.292 \(\pm\) 8.835 \\ \hline
**Ag-SeO\({}_{2}\) bmNPs** & 497.994 \(\pm\) 2.364 \\ \hline
**Ag-TiO\({}_{2}\) bmNPs** & 1142.639 \(\pm\) 5.901 \\ \hline \hline \end{tabular} \({}^{(\mathrm{a)}}\) mg ascorbic acid equivalent/100 gm dry sample. Values are average (\(n\) = 3) \(\pm\) SD.  
\end{table}
Table 1: The antioxidant results using phosphomolybdate assay.  
Figure 7: The planned free radical reaction between the antioxidants and DPPH\({}^{\star}\).  
The activity of silver nanoparticles was observed against _Streptococcus mutans_, _Escherichia coli_, and _Staphylococcus aureus_[59]. The kinetic process of silver nanoparticles against bacterial species could be hypothesized for different mechanisms: (i) Penetration into bacterial cell membranes, changing the structure of the cell membrane, and even resulting in cell death. (ii) The efficacy of nanoparticle activity could not depend upon the nanoscale but was also due to their large ratio of surface area to volume. (iii) Another hypothesis is that, during the penetration of nanoparticles into the cell membrane, the reactive oxygen species are generated and interrupt the replication of deoxyribonucleic acid via the released silver ions [60]. (iv) Additionally, the titanium nanotube surfaces containing silver, copper, zinc, or selenium showed antibacterial activity toward _Staphylococcus epidermis_ DSM3269 [61]. Our results matched with the previous study of [PERSON], et al. [62] that found that selenium nanoparticles were found to have antimicrobial activity against _Staphylococcus aureus_ (ATCC6538), _E. coli_ (ATCC8739), _Enterococcus faecalis_ (ATCC29212), _Basillus subtilis_ (ATCC6633), _Salmonella_ sp., _Klebsiella pneumoniae_ (NCIMB9111), and _Pseudomonas aeruginosa_ (ATCC027).  
The successful synthesis of these eco-friendly nanoparticles with potent antibacterial properties opens up new avenues for medical applications. These nanoparticles have the potential to revolutionize alternate therapies and contribute to the development of environmentally sustainable nanomedicines for combating bacterial infections. Additionally, the study paves the way for future research into utilizing nature-inspired approaches for green and effective medical advancements.