Green-synthesized silver nanoparticle biocomposites from Dandelion leaves: Bioactivities and metabolomics-driven mechanism study

Plant-synthesised silver nanoparticles (AgNPs) show superior bioactivity and stability to those of chemically or physically synthesised ones, and much low cost via green conversion. However, ambiguous synthetic mechanisms limit their further development. Dandelion leaves contain abundant reducing components and are readily available raw materials; however, relevant studies remain scarce. In this study, dandelion aqueous extract was used to prepare self-assembled Dandelion-AgNP solution (DAS). The AgNPs had an average size of 23.14 nm and a distinct ultraviolet (UV) absorption peak at 473 nm. Plant components in DAS enhanced stability with 74.9% intensity retention, which was higher than that achieved by traditional materials. DAS exhibited broad-spectrum antibacterial activity and advantages against drug-resistant strains. It also showed specific UV and conductivity signals upon binding Hg 2+ , with highly significant linear response (R 2 = 0.9993), indicating that it could be developed as a sensitive Hg 2+ sensor with high efficiency, excellent sensitivity, and low cost. Analysis of synthesis mechanism detected 274 upregulated and 653 downregulated chemicals with significant alterations; amino acids, organic acids, and their derivatives were key dominants as reducing agents. Oxidised phenol acid derivatives released electrons to reduce Ag + to Ag 0 and underwent demethylation and oxidation in the reaction system. The remaining chemicals adsorbed onto AgNPs surfaces, forming a stabilising organic–inorganic interface. This study developed a green and novel synthesis route for the dual-functional AgNPs and explained the complex mechanism via chemical screening and validation using data mining scheme for plant metabolomics, holding significant value for green conversion and plant-based nanotechnology.