Introduction: Laying Out Greener Routes for Nanomaterials Synthesis

In the past few years, due to advancements in science and technology, nanotechnology have emerged as a transformative field with extensive applications in biomedical, industrial, technological, and environmental sectors. Nanoparticles have unique physicochemical properties, including high surface area-to-volume ratios, more reactive, variable sizes, and multifunctional, so they are highly valuable for different applications. Conventional nanoparticle synthesis methods based on chemical and physical process involve hazardous chemicals, high energy use, and the synthesis of toxic by-products, increase environmental and health concerns. So, the growth of sustainable and environmentally benign synthesis methods has become crucial. Green synthesis of nanomaterials has appeared as a good alternative that is environmentally safe and uses the principles of sustainability. These environment-friendly methods use biological sources such as plant extracts, microbial systems like bacteria, fungi, and algae, biodegradable polymers, and other bio-based agents to synthesize nanoparticles under mild, non-toxic. These biological resources used in green synthesis play important roles in the reduction, stabilization, and functionalization of nanoparticles. In this review, various green methods for the synthesis of nanoparticles and the roles of phytochemicals, microbial metabolites, and enzymes in the fabrication of nanoparticles and stabilization have been discussed. The advantages of green synthesis over conventional methods, with less toxicity, cost-effectiveness, and improved scalability, are discussed. Also, current challenges that are related to green synthesis, like reproducibility and large-scale production, are also highlighted. This review stresses the importance of green methods in nanomaterial synthesis and encourages environmentally safe nanotechnological development.