## 3 Results
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Sample Name**} & **BET Specific Surface Area** & **Average Pore Size (nm)** \\  & **(m\({}^{2}\)/g)** & **Average Pore Size (nm)** \\ \hline S1\_15 & 18.0301 \(\pm\) 0.0694 & 4.6153 \(  
The FTIR spectra recorded for the analyzed powders are comparatively presented in Figure 10. These spectra show a well-defined absorption band, characteristic of the Zn-O bond stretching vibration at wavenumbers lower than 1000 cm\({}^{-1}\)[31]. A slight shift towards higher wavenumbers and a broadening of this band can be observed with the increase in reaction time for both Zn\({}^{2+}\) concentrations varied during the synthesis (Figure 10a,b). Thus, for a short reaction time (15 min, corresponding to S1_15 and S2_12 samples), the absorption maximum is recorded around 317 cm\({}^{-1}\), then shifting to wavenumbers of approximately 357 cm\({}^{-1}\) for the samples S1_30 and S2_30, respectively, of 369 cm\({}^{-1}\) for the samples S1_60 and S2_60. Moreover, with the increase in Zn\({}^{2+}\) concentration, a significant increase in the absorbance of the band specific to the Zn-O bond stretching vibration is observed (Figure 10c). These phenomena may be due to morphological and dimensional changes that occur with the modification of synthesis parameters, as well as additional stress that may occur in the hexagonal structure with the increase in the degree of crystallinity, the FTIR results being consistent with previous analyses. Figure 8: Comparative representation of ZnO sample size distribution (by length and thickness). Results are represented as mean \(\pm\) SD. Figure 2:0 Comparative representation of ZnO sample true density. Results are represented as mean \(\pm\) SD; different letters indicate significant differences between each sample (\(p\) < 0.05). The results regarding the antimicrobial activity of all ZnO powders are presented in Figure 2:1 Different letters (a, b, c) were used to mark statistically significant differences between samples. For all variables with the same letter, the difference between the means is not statistically significant. If two variables have different letters, it means that they are significantly different [29]. Preliminary studies showed that all strains were sensitive to interaction with ZnO, with inhibition zone diameters above 10 mm, especially for the samples with smaller precursor concentrations. Overall, enhanced antimicrobial activity was registered for the _S. aureus_ Gram-positive bacteria compared with _E. coli_ or _C. albicans_. An important role seems to be played in this case by the reaction time variation in the ZnO synthesis, registering statistically significant differences between samples with 15, 30, or 60 min reaction time (higher reaction time is associated with decreased inhibition zone diameter). This behavior tends to be less visible when decreasing the Zn\({}^{2+}\) precursor concentration, with no statistically significant differences between S3_15, S4_15, and S5_15. Incubation of cells in the presence of all ZnO powders showed good viability compared to the control (100%). The results of the study are summarized in Figure 2:2 It can be observed that both Zn precursor concentration and reaction time influence the cell viability of ZnO nanoparticles. Thus, increasing the synthesis time leads to an increase in cell viability, while increasing the Zn\({}^{2+}\) concentration leads to a decrease in cell viability. In all cases, values above 85% of viable cells compared with the Control were registered, and therefore the obtained materials cannot be considered cytotoxic. Figure 2:3 FTIR spectra for ZnO powders: (**a**) Zn\({}^{2+}\) concentration of 0.3488 mol/L, after 15, 30, and 60 min; (**b**) Zn\({}^{2+}\) concentration of 0.1744 mol/L, after 15, 30, and 60 min; (**c**) Zn\({}^{2+}\) concentration of 0.3488 mol/L and 0.1744 mol/L after 60 min.