Quercetin-conjugated gold-decorated simonkolleite nanohybrids: Insights into oxidative stress and antibacterial activity

Engineered nanomaterials (ENMs) based on Simonkolleite (SK) exhibit promising theranostic applications. The functionalization of ENMs with polyphenols holds the potential to facilitate manipulation and enhance stability, activity, and bioaccessibility. In this study, nanohybrids of SK composed of gold (Au) and quercetin were synthesized. The successful synthesis was confirmed through ultraviolet-visible, Fourier-transform infrared, Raman spectroscopy, and scanning electron microscopy. The investigation aimed to elucidate the modulation of antioxidant and oxidative parameters by these ENMs and assess their cytotoxicity and antimicrobial properties. SK nanohybrids incorporating quercetin demonstrated antioxidant properties through ORAC and DPPH evaluations, confirming the presence of the biomolecule in the inorganic matrix. SK induced ROS production and lipid peroxidation, while functionalization with Au and quercetin normalized these oxidative parameters. However, quercetin-conjugated SK promoted protein oxidation. SK and its nanocomposites diminished the viability of fibroblasts, whereas Au-doped SK and its hybrid with quercetin were cytotoxic for macrophages only at elevated concentrations (≥ 250 µg/mL). Additionally, the quercetin-conjugated ENMs exhibited antibacterial efficacy against Salmonella strains, particularly targeting S. Gallinarum and S. Enteritidis. This study demonstrated how SK nanoparticles, when functionalized with quercetin, can modulate antioxidant and oxidative mechanisms, while also showcasing their notable antibacterial activity against Salmonella strains. These findings underscore the significant role of such criteria in understanding the primary biological responses induced by ZnO-based ENMs.