Green Synthesis of Metal Nanoparticles for Environmental and Biological Applications

Abstract

Green synthesis has emerged as a sustainable alternative to physical and chemical routes for producing metal nanoparticles, using plant extracts, microorganisms and algae as natural reducing and capping agents. This article reviews the principles, biological sources, formation mechanisms and parameter control involved in green synthesis, together with the main characterisation techniques used to confirm particle properties. Environmental applications, including dye degradation, water disinfection, heavy metal remediation and pollutant sensing, are discussed alongside biological applications such as antimicrobial, anticancer and drug delivery uses. Catalytic and antimicrobial performance is strongly linked to size, shape and surface coating, which can be tuned through pH, temperature and precursor concentration. Concerns regarding toxicity, reproducibility of biological extracts and scale-up remain the principal barriers to commercial adoption. Future progress will depend on standardised protocols, mechanistic understanding and safe-by-design strategies.