In situ synthesis of gold nanoparticle coated composite derived from agar-aldehyde: characterization and their catalytic activity

[Display omitted] •Sunlight induced one pot synthesis of gold nanoparticles template bionanocomposite derived from agar-aldehyde.•Bionanocomposite (DCMA-AuNPs-CH) used as catalyst for rapid base free glucose oxidation.•Conversion and selectivity of glucose were 71 % with 91 % in aqueous solution.•Solid DCMA-AuNPs-CH can be stored at room temperature for longer time. Here we demonstrate a facile in situ preparation of agar aldehyde (Aald) functionalized gold nanoparticles (Aald-AuNPs-CH) composites with chitosan (CH) under daylight conditions. Catalytic performance of Aald-AuNPs-CH was tested on rapid (∼8 min) base free oxidation of glucose to gluconic acid under microwave heating conditions. Conversion and selectivity of glucose to gluconic acid were 71% and 91% in an aqueous medium respectively. Different reaction parameters like effect of microwave duration, temperature and catalyst dosages were studied for glucose oxidation. The abundant seaweed biomass-derived polymeric materials were explored as a catalyst for the first time. The addition advantage of the present study is the synthesized Aald-AuNPs-CH can be stored at room temperature.