Bioprospecting of seaweed: Au nanocluster synthesis, characterization and theoretical studies

Algaes are potential bioprospecting agents due to their abundance secondary metabolites that have antiviral, antibacterial, anticancer, antidiabetic, and antioxidant properties. In addition, they are frequently employed to remove oils, toxic colors, and heavy metals. Recently in this study, we have investigated the environment friendly production of gold nanoclusters utilizing Turbinaria conoides algae extract. Green synthesis of gold nanoparticles is preliminarily confirmed by color change from yellow to ruby red in the reaction mixture, and the broad surface plasmon resonance band centered at 525 nm which indicates the formation of gold nanoparticles (Au NPs). XRD confirmed the crystalline nature of the synthesized Au NPs. FT-IR confirmed the presence of carboxylic, amine, and polyphenolic groups in the algae extract used for the biosynthesis. FE-SEM results reveal the spherical morphology of the Au NPs. Algae extract can act as reducing agent as well stabilizing agent due to its organic molecules like fucoidan and polyphenolic compounds. The produced Au Nps is tested for the photocatalytic degradation of toxic dye and found to be promising. Since the metallic nanoparticles shows less band gap due to the metallic nature the mechanism is discussed WITH combined photocatalytic and inter band transitions. The production of biomedically useful gold nanoclusters using algae-mediated synthesis is therefore one-step, easy, and environmentally benign procedure for the bioprospecting of seaweed algae. • Biosynthesis of Au NPs through seaweed extract. • Au NPs Characterized by XRD, FT-IR, FE-SEM, UV-DRS and DFT. • Degradation efficiency for Au NPs is 83.6 % in 90 mins for methylene blue dye. • Geometry, HOMO-LUMO and MEP for Au 5 model cluster revealed low bandgap. • Photo catalytic and inner band electronic mechanism