ABSTRACT
The clinical tumor therapy was greatly challenged due to the complex characteristics of tumor microenvironment, however, which also provide arena for novel therapeutic strategies. In this study, poly(2-ethyl-2-oxazoline)-poly(lactic acid)-SS-poly(β-amino ester (PEOz-PLA-SS-PBAE) triblock copolymers with pH and GSH double response were synthesized, polymer micelles were prepared by thin film hydration method for loading of silybin to improve its antitumor activity. The critical micelle concentration was determined by pyrene fluorescence method as 1.8 μg·mL-1. The particle size was 155.30 ± 1.80 nm as determined by dynamic light scattering, with polydispersity index of 0.168 ± 0.004. The drug loading and entrapment efficiency of the micelles were determined by HPLC as (5.48 ± 0.04)% and (68.52 ± 0.48)%, respectively. The in vitro drug release profiles showed that the micelles have low pH sensitivity and high GSH responsiveness, and exhibited sustained release profiles. The good biocompatibility of the material was proved by measuring the hemolysis rate and cytotoxicity of the blank micelle. The cytotoxicity and apoptosis rate of tumor cells showed that the drug loaded PEOz-PLA-SS-PBAE micelles had significant inhibitory effect and apoptosis-inducing effect on MDA-MB-231 cells. The results of wounding healing assay and Transwell invasion test showed that the drug loaded PEOz-PLA-SS-PBAE micelles could significantly inhibit the metastasis of MDA-MB-231 cells. The PEOz-PLA-SS-PBAE drug-loaded micelles prepared in this study have good inhibitory effect on tumor growth and anti-tumor metastasis in vitro, which lays the foundation for the further application of silybin.