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Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions
Published on: October 10, 2016
pH-responsive dithiomaleimide-amphiphilic block copolymer for drug delivery and cellular imaging
Ting Bai1, Dongyan Shao2, Jianxin Chen1
1Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, PR China.
Abstract:
A drug delivery system that is integrated with fluorescent imaging is an emerging platform for tumor diagnostic and therapy. A pH-responsive fluorescent polymer that can respond to the surrounding medium is a desired component with which to construct an advanced drug delivery system with bioimaging characteristics and controllable drug releasing. In this work, we synthesized novel amphiphilic block copolymers of poly(ethylene glycol)-b-poly(2-(diisopropylamino) ethyl methacrylate-co-dithiomaleimide) (PEG-b-poly(DPA-co-DTM)) and poly(ethylene glycol)-b-poly(2-(dibutylamino) ethyl methacrylate-co-dithiomaleimide) (PEG-b-poly(DBA-co-DTM)) with pH-responsiveness and fluorescence. The block copolymers exhibited relatively stable fluorescence properties in different solvent and excitation-independent fluorescence behaviours. By copolymerizing the responsive segments in the molecule chain, the doxorubicin (DOX)-loaded micelles could be triggered to disassemble, thus releasing DOX at the corresponding pH values and yielding a pH-responsive drug release. Targeted deliveries of the drug within the cell were demonstrated by using the carrier responding to different pH values. The best antitumor effect was obtained by PEG-b-poly(DPA-co-DTM), which immediately released DOX as soon as it entered the tumor cells, as a result of responding to the regional pH level (pH = 6.3). The pH-responsive copolymers showed excellent biocompatibilities, as nearly 85% of cells with these fluorescent micelles survive when the testing concentration goes up to 200 μg mL-1. In all, these pH-responsive and dithiomaleimide-based fluorescent block copolymers hold great potential in future cancer diagnostic and therapeutic techniques.
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