A comprehensive review of green synthesis methods and applications of nanoparticles derived from plant extracts and microorganisms

Nano-biotechnology represents an important interface between nanotechnology and biological sciences, driven by the growing demand for biocompatible and environmentally sustainable nanomaterials. In this context, green synthesis has emerged as a viable alternative to conventional physical and chemical methods for nanoparticle production. This approach employs biological entities such as plants, bacteria, fungi, algae, yeast, and other microorganisms as natural reducing and stabilizing agents, thereby minimizing the use of toxic chemicals and harsh reaction conditions. This review critically examines current advances in the green synthesis of nanoparticles, with particular emphasis on plant-mediated and microorganism-assisted fabrication strategies. The mechanisms of nanoparticle formation, the influence of biological constituents on particle size, morphology, and stability, and commonly employed characterization techniques are discussed. Relevant literature was surveyed from established scientific databases including PubMed, ScienceDirect, Scopus, Springer, Wiley, and Taylor and Francis. The functional applications of green-synthesized nanoparticles in biomedical, agricultural, catalytic, and environmental domains are evaluated, with attention to reported performance trends and limitations. In addition, the photocatalytic and pollutant degradation potential of biologically synthesized nanoparticles is highlighted in the context of environmental remediation. This review provides a structured and critical assessment of biologically mediated nanoparticle synthesis and identifies key challenges related to reproducibility, standardization, and scalability. The insights presented aim to support future research efforts focused on translating green nanotechnology from laboratory-scale studies to practical and industrial applications.