Advances in the targeting molecules modified chitosan-based nanoformulations

Chitosan, a cationic polysaccharide, has prompted the continuous impetus for the development of safe and effective drug delivery systems due to its unique properties such as mucoadhesive feature, absorption enhancement and active functional groups for chemical modifications. By using chitosan-based nanoformulations, many studies have attempted to improve the dispersion of loaded hydrophobic drugs in aqueous environment, protect the encapsulated proteins and genes against enzymatic degradation, and increase their absorption by target tissues. It's noteworthy that the derivatization of chitosan-based carriers with a ligand leads to the selective targeting of the nanoformulations to selected cells, thereby facilitating far more sensitive internalization and localization of nanoformulations for diseases' diagnosis and treatment. As such, this review focuses on some of the most poignant reports of the utility of targeting molecules such as carbohydrates, antibodies, peptides and some small molecules in chitosan-based nanoformulations for targeted delivery. Additionally, the affinity mechanism of different targeting molecules and the pros and cons of their conjugation strategies will be illustrated summarily.