As a nature polymer

chitosan has been attracted more and more attention in drug delivery systems because of its outstanding properties

such as non-toxic

biodegradable and biocompatible. Chitosan based nanocarriers can be prepared easily

and recently

the researches of these nanocarries are very novel too. On the basis of the propulsion to formulate nanocarriers

the review is to summerize the latest preparation of modified chitosan derivatives from four aspects:covalent crosslinking

ionic crosslinking

polyelectrolyte complex

and the self-assembly of hydrophobically modi? ed chitosan. And the review is to introduce the effect on drug delivery of drug loading content

drug loading efficiency

release behavior and cytotoxicity

furthermore

outlook the future application.