Chitosan-based nanocarriers with pH and light dual response for anticancer drug delivery

Currently, the major challenge for cancer treatment is to develop new types of smart nanocarriers that can efficiently retain the encapsulated drug during blood circulation and quickly release the drug in tumor cells under stimulation. In this study, the dual pH-/light-responsive cross-linked polymeric micelles (CPM) were successfully prepared by the self-assembly of amphiphilic glycol chitosan-o-nitrobenzyl succinate conjugates (GC-NBSCs) and then cross-linking with glutaraldehyde (GA), which was synthesized by grafting hydrophobic light-sensitive o-nitrobenzyl succinate (NBS) onto the main chain of hydrophilic glycol chitosan (GC). The GC-NBSC CPMs exhibited good biocompatibility according to the MTT assay against NIH/3T3 cells. The cell viability was maintained higher than 75% after 24 h incubation with CPMs even at a high concentration of 1.0 mg mL(-1). The hydrophobic anticancer drug camptothecin (CPT) was selected as a model drug and loaded into GC-NBSC CPMs. The results of in vitro evaluation showed that the encapsulated CPT could be quickly released at low pH with the light irradiation. Meanwhile, the CPT-loaded CPMs displayed a better cytotoxicity against MCF-7 cancer cells under UV irradiation, and IC50 of the loaded CPT was as low as 2.3 μg mL(-1), which was close to that of the free CPT (1.5 μg mL(-1)). Furthermore, the flow cytometry and confocal laser scanning microscopy (CLSM) measurements confirmed that the CPT-loaded CPMs could be internalized by MCF-7 cells efficiently and release CPT inside the tumor cells to enhance the inhibition of cell proliferation. Thereby, such excellent GC-NBSC CPMs provide a favorable platform to construct smart drug delivery systems (DDS) for cancer therapy.