From Plant Metabolites to Functional Nanomaterials: Advances in Phytochemical-Mediated Silver Nanoparticle Synthesis and Applications

Abstract

Phytochemical-assisted green synthesis of silver nanoparticles offers a sustainable alternative to conventional fabrication routes by utilising plant-derived metabolites as multifunctional reducing, capping, and stabilising agents. Polyphenols, flavonoids, tannins, alkaloids, and related biomolecules mediate the reduction of Ag+ to Ag0 under mild conditions while controlling nucleation, growth, and surface stabilisation, thereby dictating nanoparticle size, morphology, and colloidal stability. This review establishes clear links between phytochemical composition and the mechanistic pathways governing nanoparticle formation and biofunctional performance. Variations in extract chemistry influence electron transfer dynamics, surface functionalisation, and physicochemical properties, ultimately modulating biological activity. Enhanced antimicrobial and antioxidant effects arise from synergistic interactions between the silver core and phytochemical capping layers, promoting membrane disruption, reactive oxygen species generation, and biomolecular interference. Despite promising applications in antimicrobial coatings, food preservation, agriculture, and anticancer systems, key challenges remain, including compositional variability, limited mechanistic standardisation, and insufficient toxicological evaluation. Nonetheless, phytochemical-assisted synthesis provides a tunable and sustainable platform for AgNP production, aligning nanomaterial design with green chemistry principles while enabling multifunctional bioactivity. By integrating phytochemical composition, mechanistic synthesis pathways, and structure–activity relationships across diverse applications, this review provides a critical framework for the rational design, standardisation, and scalable development of next-generation phytochemical-mediated AgNP systems.