Green-synthesized nanoparticles: Mechanisms, characterization, challenges and future perspectives

Abstract:

The synthesis of nanoparticles (NPs) using green chemistry principles has emerged as a transformative approach in nanotechnology, offering a sustainable alternative to conventional physical and chemical fabrication routes that rely on hazardous reagents and energy-intensive processing. This review synthesises current knowledge on the synthesis, characterization, and application of green-synthesized nanoparticles, with particular emphasis on plant, microbe, and biomolecule-mediated routes. Phytochemicals such as flavonoids, terpenoids, and phenolic compounds act as natural reducing and capping agents, yielding nanoparticles with enhanced biocompatibility, stability, and antimicrobial efficacy while minimising toxic by-products and energy consumption. Particular attention is given to nanoparticles derived from forest and agroforestry species including neem (Azadirachta indica), Jatropha curcas, Lantana camara, Swietenia mahagoni, Syzygium aromaticum, and Terminalia catappa which illustrate the breadth of biogenic precursors available for sustainable nanomaterial fabrication. The review further examines the physicochemical factors governing nanoparticle formation, contrasts top-down, bottom-up, and biological synthesis strategies, and summarises the principal techniques used for nanoparticle characterization. The wide-ranging applications of green nanotechnology in medicine, agriculture, environmental remediation, energy, textiles, and food packaging are discussed alongside the persistent challenges of process standardisation, mechanistic understanding, industrial scale-up, and nanotoxicology. Addressing these gaps through interdisciplinary research will be essential to realising the full potential of green-synthesized nanoparticles as a cornerstone for the development of sustainable nanotechnology across biomedical, agricultural, environmental, and industrial sectors.