Influence of plant-derived extracts on the synthesis, physicochemical properties, and applications of metal and metal oxide nanoparticles

Plant extracts provide a green, environmentally friendly alternative to conventional chemical and physical nanoparticle fabrication processes, with the benefits of evading toxicity, high energy needs, and environmental contamination. Phytochemicals such as flavonoids, terpenoids, alkaloids, and phenolic acids act as in situ reducing, capping, and stabilizing agents, permitting controlled fabrication of metal (Ag, Au, Cu) and metal oxide (ZnO, TiO 2 , Fe 3 O 4 ) nanoparticles with size, shape, crystallinity, and surface charge controllability. This review critically analyzes the mechanistic role of these phytochemicals on nucleation, growth, and stabilization processes, emphasizing the relationship between synthesis parameters and nanoparticle physicochemical properties. Quantitative data reported in Tables 1–10 reveal particle size variations (3–80 nm) and pH, temperature, precursor concentration, and extraction-dependent morphology changes. Applications of the synthesized nanoparticles as antimicrobial, catalytic, and environmental remediation agents are discussed, along with challenges of reproducibility and scale-up. The review highlights plant-mediated nanoparticle synthesis as a promising avenue toward reproducible and green nanomaterials with a focus on the need for standard protocols for guaranteeing safety and consistency.