A Review of Green Synthesis of Silver Nanoparticles Using Plant Extracts: Mechanisms, Characterization, Comparative Analysis, Challenges, and Emerging Biomedical and Environmental Applications

Abstract

Silver nanoparticle (AgNP) production has attracted considerable interest due to its remarkable physicochemical properties and wide-ranging applications in catalysis, healthcare, and environmental science. Among various synthesis strategies, green synthesis using plant extracts has emerged as an efficient, economical, and environmentally friendly alternative to conventional chemical and physical methods. This approach uses abundant plant phytochemicals, including terpenoids, alkaloids, phenolics, and flavonoids, which act as natural reducing, stabilizing, and capping agents during nanoparticle formation. Recent advances have improved control over nanoparticle shape, size, and stability by optimizing parameters such as temperature, reaction time, pH, and extract concentration. This review critically synthesizes recent literature on the plant-mediated green synthesis of AgNPs by comparing different plant extracts, synthesis strategies, characterization techniques, and application outcomes. It also identifies current research challenges, knowledge gaps, and future directions for developing sustainable and scalable silver nanoparticle technologies. Comparative studies using different plant extracts reveal significant variations in reduction efficiency, particle size distribution, and application-specific performance. Green-synthesized AgNPs demonstrate strong antioxidant, antimicrobial, catalytic, and sensing capabilities, making them promising for biological applications, wastewater treatment, and pollutant degradation. Overall, the review highlights recent progress in plant-mediated AgNP synthesis, underlying green synthesis mechanisms, the essential role of phytochemicals, and the functional relevance of AgNPs, supported by selected reference studies and comparative assessments of synthesis outcomes.