Biosynthesized metallic nanoparticles for sustainable environmental remediation: mechanisms, applications, and future perspectives

Increasing environmental pollution crisis due to toxic pollutants such as heavy metals, synthetic dyes, and hazardous waste necessitates the urgent establishment of environmentally benign and sustainable remediation technologies. This review summarizes recent advances in the biosynthesis of metallic nanoparticles (BMNPs) application of green pathways involving biological agents such as plants, bacteria, fungi, and enzymes. These biogenic nanoparticles have superior physicochemical characteristics such as high surface area, stability, reactivity, and catalytic activity, making them extremely effective in contaminant degradation, adsorption, and sequestration. We elucidate the basic principles and mechanisms of biosynthesis, emphasising the contributions of varied biological agents towards metal ion reduction and stabilization into nanoparticles. Further their applications in controlling environmental pollution, such as removal of heavy metals (mercury ions, Hg2⁺), degradation of dyes (methylene blue), and decontamination of toxic gases (nitrogen oxides, NOₓ) has been illustrated in detail. Additionally, critical analysis of the environmental fate, ecotoxicity, and regulatory issues of biogenic nanoparticles, as well as toxicity assessment methods has been carried out. It also highlights the recent development on nanoparticle functionalization and nanocomposite synthesis to extend their reactivity and stability. Despite promising outcomes, challenges such as scalability, control over nanoparticle properties, variability in biological sources and the need for a complete understanding of ecotoxicological behaviour still remains unresolved. To address this gap, integrating biosynthesis with advanced engineering tools and real-time monitoring technologies becomes very crucial. Such integration pivots on the incorporation of green nanotechnology into conventional remediation techniques. It further emphasizes the necessity of regulatory framework, standardized protocol, and interdisciplinary collaboration to facilitate the transition of these green nanomaterials from laboratory to widespread field application. Such a holistic approach offers sustainable solution to address global environmental challenges and achieving effective environmental restoration and pollution management.