Figure 5.

Schematic diagram showing mechanism of intracellular NPs synthesis in algae. Metallic ions get inside the cytoplasm, thereby getting reduced by nitrate reductase enzymes produced from different biochemical reactions. Several biogenic molecules act as capping agents to stabilize finally producing biogenic metallic NPs. However, the extracellular mechanism involves the trapping of metal ions near the cell wall or ECMs, which contain several reducing agents, as well as there is secretion of reducing enzymes and metabolites to the external environment. Altogether, they assist the reduction of metal ions to finally produce capped and stabilized metallic NPs. Created with BioRender.com with publication license.