From Geothermal Flora to Green Nanotechnology: Phytochemical Insights into Silver Nanoparticle Synthesis

Abstract

Physical and chemical synthesis of silver nanoparticles (AgNPs) often involves high energy consumption and hazardous reagents. Green synthesis using plant extracts provides a more sustainable alternative, as plant metabolites act as reducing and stabilizing agents. This review examines the potential of plants from geothermal areas in Aceh as bioreductants for AgNP synthesis, focusing on synthesis mechanisms, nanoparticle characteristics, antimicrobial activity, and development challenges. A narrative review of relevant literature indicates that geothermal conditions may influence plant phytochemical profiles, including polyphenols, flavonoids, tannins, and terpenoids, which facilitate the reduction of Ag⁺ to Ag⁰ and stabilize the resulting nanoparticles. Notably, Lantana camara from the Ie Seu'um geothermal area has been reported to produce AgNPs with a mean size of 44 nm, smaller than those obtained from the same species in non-geothermal areas. AgNPs synthesized using plants from geothermal habitats also exhibit potential antimicrobial activity against Gram-positive and Gram-negative bacteria and fungi. However, evidence remains limited, and challenges include phytochemical variability, reproducibility, insufficient standardization, ecotoxicity, and risks of overharvesting local flora. Future research should prioritize comparative studies, chemometric authentication, reaction optimization, standardized safety assessment, and nanocomposite development. Aceh's geothermal flora represents a promising but insufficiently validated resource for sustainable AgNP synthesis, warranting systematic investigation to establish its advantages and practical applicability.