Synthesis, structural profiling, and antioxidant potential of eco-friendly silver nanoparticles with a long shelf life

Silver nanoparticles (AgNPs) are widely used in biomedical and topical products; however, conventional synthesis methods often involve toxic reagents and raise environmental concerns. This study aims to address the need for scalable green nanotechnologies, while also reporting the novel synthesis of AgNPs using an aqueous extract of Boesenbergia rotunda (fingerroot), a medicinal plant rich in phenolic and flavonoid compounds. The novel synthesis of AgNPs highlighted in this study functions as a highly efficient, dual-action reducing and stabilizing agent under mild, eco-friendly conditions, which also enables the formation of a robust phytochemical corona without the need for synthetic surfactants. The AgNPs formation was confirmed through the adaptation of UV–Vis spectroscopy, which showed a surface plasmon resonance peak at ∼400 nm and a color change from pale yellow to reddish-brown. The transmission electron microscopy revealed predominantly spherical and well-dispersed nanoparticles. In addition to this, an analysis of the Zeta potential and particle size indicated high colloidal stability, with the X-ray diffraction confirming crystalline metallic silver. Further analysis of the ATR–FTIR suggested that the hydroxyl and carbonyl groups from the phytochemicals facilitated Ag⁺ reduction and nanoparticle stabilisation, forming a phytochemical corona. Insightfully, the synthesized AgNPs exhibited a remarkable long-term colloidal stability for up to 10 months and a significant antioxidant activity, with a DPPH IC₅₀ value of 14.96 ± 0.18. These findings highlight a paradigm shift toward sustainable biomaterials, demonstrating that B. rotunda -derived AgNPs hold profound translational potential for next-generation sustainable consumer and medical products, particularly in advanced dermatological formulations such as functional skin patches.