Gold Nanoparticles Supported on Modified Chitosan Oligomers: Stability and Catalytic Performance

Abstract

This study investigates the synthesis and stabilization of gold nanoparticles (Au-NPs) ≈20 nm in diameter, using modified chitooligosaccharide (COS) as a biopolymeric matrix, emphasizing their application in catalysis. The modified COS serves as a stabilizing agent for the Au-NPs, enhancing their catalytic efficiency and the recovery of the catalyst. Structural characterization techniques, including UV-vis spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy, are employed to analyze the polymeric matrices and confirm the successful integration of Au-NPs. The higher stability of Au-NPs in P2 is attributed to the rigid imidazole rings, which form a more ordered network than the flexible diimine bonds in P1. The catalytic performance of the Au-NPs on modified COS is evaluated in the isomerization reaction of sulfamethazine-azo-aniline, achieving up to 73% efficiency in the third cycle of reuse. This research highlights the promising role of biopolymer-based catalysts in advancing sustainable and efficient organic synthesis.