A pH-Sensitive Polymeric Micellar System Based on Chitosan Derivative for Efficient Delivery of Paclitaxel

In this study, an amphiphilic conjugate based on mPEG and cholesterol-modified chitosan with hydrazone bonds in the molecules (mPEG-CS-Hz-CH) was successfully synthesized. Using the polymer as the carrier, the paclitaxel (PTX)-loaded mPEG-CS-Hz-CH micelles were prepared by an ultrasonic probe method. The mean particle size and zeta potential of the optimized PTX-loaded micelles were 146 ± 4 nm and +21.7 ± 0.7 mV, respectively. An in vitro drug release study indicated that the PTX-loaded mPEG-CS-Hz-CH micelles were stable under normal physiological conditions (pH 7.4), whereas rapid drug release was observed in the simulated tumor intracellular microenvironment (pH 5.0). An in vitro cytotoxicity study demonstrated the non-toxicity of the polymer itself, and the PTX-loaded micelles exhibited superior cytotoxicity and significant selectivity on tumor cells. An in vivo antitumor efficacy study further confirmed that the PTX-loaded micelles could improve the therapeutic efficacy of PTX and reduce the side effects. All these results suggested that the mPEG-CS-Hz-CH micelles might be promising pH-sensitive nanocarriers for PTX delivery.