Green synthesis of nanoparticles: a comprehensive review of biogenic methods and their applications

Nanotechnology focuses on the synthesis and application of nanoparticles with unique physicochemical properties at the nanoscale. Green synthesis has emerged as a sustainable alternative to conventional fabrication methods, utilizing biological systems such as plants, bacteria, fungi, yeast, and viruses to produce biocompatible nanoparticles while minimizing toxic by-products. Metallic and metal oxide nanoparticles, including silver, gold, zinc oxide, and iron oxide, have demonstrated significant potential in drug delivery, antimicrobial therapy, cancer treatment, water purification, and environmental remediation. Despite these advantages, biogenic synthesis faces challenges related to reproducibility, variability of biological precursors, and limited control over particle size and morphology, restricting large-scale industrial implementation. Recent advances in artificial intelligence and machine learning offer opportunities to optimize synthesis conditions and enable the rational design of functional nanomaterials. This review critically examines biogenic nanoparticle synthesis, its mechanisms, advantages, limitations, and emerging strategies to improve scalability, standardization, and industrial applicability.