Chitosan-decorated nanoparticles for drug delivery

Chitosan is a natural polymer extensively applied in the cosmetic, textile, food, and agricultural industries. Chitosan possesses biocompatibility, biodegradability, and antibacterial activity; thus, it is employed for a variety of biomedical applications. Furthermore, due to its ability to modify the physicochemical features of preformed nanoparticles, numerous research groups have exploited the coating of nanoparticles with chitosan to obtain new biological properties. In this regard, the decoration with chitosan confers the exposure of electro-charged amino groups towards the surface of nanoparticles, which is evidenced by positive zeta potentials. Although other biomaterials may provide a positive zeta potential, these involve low robust production methods, whereas chitosan-decorated nanoparticles may be obtained by straightforward ionic gelation techniques. Concerning this, methods of physical adsorption are the most employed because they involve a short time and low resources. However, the coating of nanoparticles through cross-linking with chitosan represents an exciting option. In this article, we perform a description of the structure and physicochemical chitosan properties. Moreover, we describe different strategies for coating with chitosan the surface of distinct types of nanoparticles and the subsequent changes in their biological and physicochemical properties. Finally, we mention several biomedical applications of these chitosan-decorated nanoparticles and discuss future perspectives.