Green synthesis of antioxidant and low-toxicity gold and silver nanoparticles using floral extracts

In this study, gold (AuNPs) and silver (AgNPs) nanoparticles were synthesized using floral extracts of H. sabdariffa and P. domesticum , aiming to develop eco-friendly nanomaterials with antioxidant and low toxicity properties. The green synthesis method produced stable nanoparticles larger than 30 nm, which were characterized by high antioxidant activity, low cytotoxicity, and minimal ecotoxic effects compared to those obtained via conventional chemical reducers (trisodium citrate and tannic acid). Among the most promising results, promising results, AuNPs and AgNPs synthesized with H. sabdariffa exhibited the highest antioxidant capacity (up to 43.13% more than P. domesticum ) and negligible cytotoxicity in both A549 and HFF cell lines, with AuNPs even enhancing cell viability. AgNPs from P. domesticum showed improved resistance to UV exposure buy slightly higher cytotoxicity. In contrast, chemically synthesized NPs (Q1 and Q2) induced significant cell death and exhibited increased oxidative states under UV-Vis-NIR radiation. Toxicity tests on cyanobacteria ( Fisherella musicola ) confirmed the biocompatibility of green synthesis NPs, with no significant growth inhibition observed for AuNPs:Hs and AgNPs:Hs. Overall, this work confirms that anthocyanin rich floral extracts can act as effective reducing and stabilizing agents, producing multifunctional nanoparticles suitable for biomedical and cosmetic applications. These findings highlight the potential of green nanotechnology to deliver safer and more sustainable nanoparticle formulations.