GREEN SYNTHESIS OF NANOPARTICLES: MECHANISMS, CHARACTERIZATION, AND EMERGING APPLICATIONS

Abstract

The pursuit of sustainable and biocompatible technologies has driven significant interest in the green synthesis of nanoparticles (NPs) for drug delivery applications. Green synthesis employs plant extracts, microorganisms, and biopolymers as reducing and stabilizing agents, eliminating the need for toxic chemicals typically used in conventional synthesis methods. This environmentally friendly approach produces nanoparticles with enhanced biocompatibility, tunable physicochemical properties, and inherent bioactivity, making them highly suitable for targeted therapeutics and diagnostics. Metallic nanoparticles (e.g., silver, gold), metal oxides (e.g., zinc oxide, magnetite), and biopolymeric carriers (e.g., chitosan) synthesized via green routes have demonstrated broad utility in oncology, antimicrobial therapies, vaccine delivery, gene transfection, and theranostic systems. Functionalization strategies such as PEGylation, surface ligand attachment, and hybridization with polymers further optimize their stability, targeting, and controlled release profiles. Despite these advantages, challenges remain, including variability in biological source composition, scale-up limitations, and regulatory hurdles regarding reproducibility and safety. This review highlights the mechanisms underlying green synthesis, summarizes representative nanoparticle systems, and examines their applications in drug delivery. Special emphasis is placed on recent advancements such as stimuli-responsive and multifunctional nanocarriers, as well as integrated theranostic platforms combining therapy and imaging. Future perspectives stress the need for standardized production protocols, scalable manufacturing, and in-depth preclinical and clinical evaluations to accelerate the translation of these eco-friendly nanotechnologies into pharmaceutical use. Green-synthesized nanoparticles, with continued innovation and regulatory alignment, hold promise as next-generation drug delivery systems offering safer, cost-effective, and sustainable solutions.