Physicochemical studies of the structure of chitosan and chitosan ascorbate nanoparticles

The structure and characteristics of chitosan (CS NPs) and chitosan ascorbate nanoparticles (CSA NPs) were studied by physicochemical methods. Atomic force microscopy showed that the sizes of CS NPs and CSA NPs range from 500 nm to 2 μm and from 100 to 600 nm, respectively, and depend on the molecular weight of the starting chitosan. Absorption bands appear in the IR spectra, confirming the structure of CS NPs and CSA NPs. The UV spectra of CS NPs and CSA NPs revealed that the absorption bands undergo redshifts, which are related to the interaction of the crosslinking agent and the functional groups of the starting components. X-ray diffraction revealed an increase in the degree of crystallinity of CS NPs and CSA NPs, which is also related to the presence of a crosslinking agent that facilitates a higher ordering of the polymer macromolecules.