Green synthesis of silver nanoparticles by algae: Advancements, challenges and sustainable prospects

Noble nanoparticles, particularly silver nanoparticles (AgNPs), renowned for their high surface-area-to-volume ratio and superior localized surface plasmon resonance, have garnered significant attention for their applications in multifaceted fields. However, conventional synthesis methods of AgNPs often involve toxic chemical reducing agents and high energy consumption, posing several environmental concerns. To address these challenges and promote sustainable production, researchers have increasingly explored environmentally friendly alternatives, including the integration of plant, bacterial, and algae feedstocks. Algae have emerged as a promising sustainable source owing to their efficient growth and cultivation. The algae-mediated synthesis of AgNPs harnesses the intracellular and extracellular metabolites of algae, offering a green and eco-friendly approach. This comprehensive review seeks to delve into both conventional approaches and contemporary algae-mediated protocols employed in AgNPs fabrication, emphasizing the vital shift toward sustainable feedstock sources. Furthermore, this review highlights the global market trends and diverse applications of AgNPs, ranging from wastewater treatment and pollutant remediation to antimicrobial coatings and biosensors. By integrating essential characterization tools with the fundamentals of nanoparticle nucleation, this review discusses several synthesis factors that provide insights for process optimization. This review highlights the versatile potential of algae in shaping the future of sustainable and clean AgNP synthesis. It emphasizes recent advancements in the field, driven by global initiatives in algae cultivation and nanotechnology policies, while also addressing the key challenges associated with the eco-friendly production of AgNPs. •Green synthesis and diverse applications of silver nanoparticles were highlighted.•Smaller nanoparticles fetch higher prices due to their larger specific surface area.•The plasmon resonant band of silver nanoparticles falls within the solar spectrum.•Algae facilitate silver ion reduction via intracellular and extracellular pathways.•Unravelling the reaction mechanisms of green synthesis poses a persistent challenge.