Chitosan supported silver nanostructures as surface-enhanced Raman scattering sensor: Spectroscopic and density...

In this work, nanostructures comprising silver nanoparticles supported on a wrinkled chitosan matrix (Ag@Ch) were successfully synthesized by a simple aging process at room temperature for four days through self-assembly. Chitosan, a natural polysaccharide was used as a support as well as a reducing agent for the formation of Ag nanostructures and the creation of hotspots for SERS activity. The fabricated Ag@Ch nanostructures were characterized by several spectroscopic techniques and were used as a surface-enhanced Raman scattering (SERS) substrate. The effect of wet, dry, and liquid samples on the SERS enhancement has been studied and was found to be effective for sensing Methylene blue, Crystal Violet, and p-Nitrophenol with detection limits of 3.8, 8.1, and 8.2 ppb respectively. The SERS enhancement of the Ag@Ch was attributed to the combination of both electromagnetic (EM) and chemical effects (CE). Density functional theory (DFT) calculations were used to explain the observed surface enhancement. Good agreement was observed between the experimental and simulated spectra.