| Chemotherapy is still the main treatment strategy for tumors. However, its enormous side effects limited the clinical application. With the development of high-end nano technology, a growing number of nanomaterials applied in pharmaceutics, biomedicine and other fields. Among them, novel nano materials as a drug delivery system(DDS)could quantitatively and precisely delivery medicines to the target site on time for the maximum efficacy and the minimum side effects. Nano-materials have revolutionized the antitumor drug delivery, successfully reduced chemotherapy drug toxicity and improved the treatment of tumor.Over the past couple of decades, polymeric micelle, liposome, nanoparticle, nanogel and other nanometer system have achieved tremendous research progress in targeted anticancer drugs delivery. Polymer micelle is one of the fastest developing and most promising drug carrier in nearly a decade. However, high targeting efficiency, circulation stability in vivo and controllable drug intracellular release are several challenges for micelles in clinical application.Therefore, we designed cRGD-decorated and redox-sensitive micelles(RSCMs) based on amphiphilic polymer of poly(styrene-co-maleic anhydride)(SMA) and got the following experimental results:(1) RSCMs exhibited a homogeneous spherical shape and with a low polydispersity of 0.087 and an average diameter of 106.12 nm. Pyrene fluorescence probe measured the critical micelle concentration(CMC) of RSCMs was low to 2.5 μg/mL, reflected the good stability against dilution. Proton nuclear magnetic resonance(1H-NMR) result confirmed that cRGD peptide was modified to the surface of SMA micelle successfully. By comparison, after shell crosslinking by cystamine, the micelles possessed better stability against extensive dilution by water or N,N’-dimethylformamide(DMF), better long-term stability and stronger reductive response towards dithiothreitol(DTT).(2) Hydrophobic doxorubicin(DOX) was used as a model drug to evaluate the loading and release performance of SMA. The SMA micelles displayed high drug loading capacity with an encapsulation efficiency(DLE) of 72.1~82.7%(w/w) and a drug loading(DLC) of approximately 14.1~19.2%(w/w). The in vitro release behavior showed that the release of DOX from shell crosslinked micelles was less than 25% under physiological conditions over a period of 24 h. Nevertheless, when added 10 mM DTT, the release rate of shell crosslinked micelles obviously increased(60%, 8 h).The release profile of DOX from shell crosslinked micelles exhibited a typical redox-responsive property.(3) MTT assays in B16F10 cells indicated that RSCMs has no obvious inhibitory effect on cell growth even if its concentration up to 500 μg mL-1(48 h, cell viability > 80%),it displayed favorable biocompatibility. Moreover, the lower IC50 value of cRGD-DOX-ss-M displayed that it could be more effective than other groups. Using fluorescence microscope and confocal laser scanning microscopy to qualitatively observe the internalization process of micells in different cells. And flow cytometry was employed to quantitative determine intracellular fluorescence intensity. Both the qualitative and quantitative results demonstrated that cRGD-DOX-ss-M promoted the cell uptake of the drug, which possessed much superior specificity to target cells and excellent stimulated release characteristic in cytoplasm. Notably, cRGD-DOX-ss-M could more efficiently transform and release DOX into αvβ3 integrin over-expressed cancer cells(B16F10) than the negative control cells(Hela), it effectively demonstrated the active targeting property attributed to cRGD peptide.In conclusion, these cRGD-modified redox-sensitive micelles provide a favourable technology platform in targeted anticancer drug delivery and control release, and it have great potential to be developed as a perfect targeted anticancer drug delivery system. |
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