Box Behnken design-based optimized green synthesis of lanthanum oxide submicroparticles using Quercus Infectoria galls extract and their antimicrobial activities

This study focuses on the green synthesis of lanthanum oxide submicroparticles (LO-SMPs) using the galls extract of Quercus Infectoria. Response surface methodology (RSM) based optimization using Box-Behnken design (BBD) was performed and a linear model was found to be best fitted and was used to evaluate the influence of time, the concentration of salt and volume of the extract on the synthesis of LO-SMPs. The optimized conditions for the synthesis were found to be 80 min, 2 mM and 12 mL with the absorbance of 1.74. ANOVA analysis reveals significant results based on their p-value. Synthesized LO-SMPs were characterized using various techniques such as UV–Vis, FTIR, SEM, EDX, XRD and DLS analysis. The morphology of LO-SMPs was analyzed using SEM and was found to be poly-dispersed spherical clusters. The body-centered cubic structure of LO-SMPs was confirmed by XRD. Furthermore, the nanoparticles inhibited three pathogenic microorganisms (S. aureus, E. coli, and P. multocida) and the inhibition potential of LO-SMPs showed enhanced activities compared to the plant extract. It was observed that high concentrations of LO-SMPs (30 mg/mL) showed a larger zone of inhibition against E. coli and P. multocida at 32 mm and 28 mm, respectively. The findings revealed that LO-SMPs have promising antibacterial activity, which might have potential as therapeutic agents, which need further investigation on the cytotoxicity and biocompatibility studies on cell lines.