Onion-structure bionic hydrogel capsules based on chitosan for regulating doxorubicin release

Inspired by the multilayer structure of onion, herein, a novel strategy to prepare bionic multilayer hydrogel capsules for inhibiting burst release of doxorubicin (DOX) is reported. The bionic multilayer hydrogel capsules are prepared by the ionotropic crosslinking method. Compared with monolayer hydrogel capsules, the multilayer hydrogel capsules can largely homogenize the distribution of DOX and suppress the concentration gradient of DOX between the outermost hydrogel layer and external environment and the dense cuticular membranes of capsules can restrict the migration and diffusion of DOX. As a result, a significant inhibition of the burst release of DOX can be achieved. Moreover, the bionic multilayer hydrogel capsules demonstrate pH sensitivity and good biocompatibility to human epidermal keratinocyte (HaCaT) cells. This work opens up a new horizon in the burst release of biomaterial-based hydrogels for drug delivery system.