Preparation and Characterization of Vanillin Cross-linked Chitosan Microspheres Modified by Silver Nanoparticles

In this work, the vanillin cross-linked chitosan microspheres were firstly prepared by emulsion chemical cross-linking method with vanillin as a cross-linker. Subsequently, with polyvinylpyrrolidone as a nanoparticle stabilizer and dispersant, silver nanoparticles were modified onto the surface of vanillin cross-linked chitosan microspheres by in situ reduction with ascorbic acid to obtain silver nanoparticles modified microspheres. The chitosan and two kinds of microspheres were characterized by SEM, FTIR and XRD. The SEM images showed that the two kinds of microspheres had clear and well-defined spherical shapes with an average particle size of 4.2 mu m and the silver nanoparticles were then evenly dispersed on the surface. The FTIR spectra revealed that chitosan was successfully cross-linked by vanillin through Schiff base reaction and hydrogen bond interactions. The X-ray diffraction pattern of vanillin cross-linked chitosan microspheres modified with silver nanoparticles indicated that the silver nanoparticles had a face-centred cubic structure with an average particle size of 44.4 nm confirmed by SEM, which proved the successful synthesis of target composite microspheres.