Study On Multifunctional Nanoparticles Based On Chondroitin Sulfate

Breast cancer is a kind of malignant tumor that cause the highest morbidity and mortality rate among females.Chemotherapy is the primary treatment strategy in clinical.However,the therapeutic efficacy of common chemotherapeutic drugs(e.g.paclitaxel and doxorubicin)has been greatly restricted by their poor water solubility and selectivity for tumor cells.Besides,mono-chemotherapy is prone to inducing multiple drug resistance and enhancing pulmonary metastasis,resulting in final cancer recurrence.Herein,a novel redox-responsive chondroitin sulfate-based drug delivery system was constructed with the expectation to improve the above-mentioned problems.In this study,paclitaxel(PTX)was used as a model drug for breast cancer chemotherapy.Meanwhile,quercetin(QT),as a chemosensitizer and chlorin(Ce6),as a photosensitizer,were also introduced into the self-assembled drug delivery system to enhance the chemosensitivity of PTX against multidrug resistant breast cancer and improve the therapeutic efficacy by combining photodynamic therapy(PDT)with chemotherapy.QT and Ce6 were respectively grafted onto the backbone of chondroitin sulfate(Chs)via amidation reaction using cystamine(CYS)as a redox-sensitive linker.1H-NMR,FT-IR and UV confirmed the successful synthesis of Chs-CYS-QT/Ce6(CQE)polymers.In addition,the content of QT and Ce6 in the polymer was determined by UV spectrophotometer to be(6.80±0.83)%and(5.17±0.68)%,respectively.PTX-loaded polymeric nanoparticles(PTX/CQE NPs)were prepared using a sonication method and uniform spherical nanoparticles were acquired.The particle size of PTX/CQE NPs measured by DLS was about 120 nm and zeta potential was-22 mV.Drug loading(DL)of PTX determined using HPLC can be up to 14.84%.In addition,the size distribution changes of CQE NPs and the in vitro release behavior of PTX from PTX/CQE NPs under different reducing conditions were investigated,respectively.According to the results,nanoparticles exhibit redox-sensitive property and are expected to achieve triggered drug release in the tumor sites.The results of western blot study showed that QT could downregulate the expression of P-gp.Thus,QT was expected to enhance the chemosensitivity of PTX against drug-resistant cancer cells.The in vitro anticancer activity of nanoparticles was investigated by in vitro cytotoxicity,apoptosis,and live/dead cell staining assays.Cytotoxicity results revealed that QT enhanced the anticancer activity of PTX against MCF-7/ADR cells,and 'PTX/CQE NPs plus irradiation' group exhibited the strongest cytotoxicity.Besides,'PTX/CQE NPs plus irradiation' group induced the highest total apoptosis rate(37.55%),suggesting that the combination of enhanced chemotherapy with PDT was a superior strategy for anticancer therapy.DCFH-DA,a ROS-sensitive probe,was used to investigate the ability of nanoparticles to generate reactive oxygen species(ROS)in cells.In the presence of laser irradiation,CQE NPs could generate more intracellular ROS,which could exert PDT.Moreover,mitochondrial membrane potential detection results showed that PDT could make mitochondrial membrane potential decreased.Collectively,CQE NPs could generate ROS with irradiation and promote cell apoptosis.Confocal microscopy(CLSM)was used to observe the cellular uptake and subcellular distribution of nanoparticles.According to the results,CQE NPs could significantly promote the intracellular uptake of Ce6compared with free drugs.In addition,mitochondria and lysosomes were labelled to track the subcellular distribution of CQE NPs and it was found that CQE NPs can be distributed in mitochondria and lysosomes after internalization,which would greatly promote the mitochondrial damage by ROS and cut off the 'energy supply' of p-gp.Thus,PDT-induced cascades of MCF-7/ADR cell apoptosis and anticancer effect of PDT on MCF-7/ADR cells could be enhanced.The real-time distribution of free Ce6 and CQE NPs in tumor-bearing mice after different administration time was investigated.Compared with free Ce6,CQE NPs exhibited tumor-targeting property and prolonged retention time in tumor sites,which would enhance the anticancer activity.The anticancer results showed that the'PTX/CQE NPs plus irradiation' group exhibited the highest tumor growth inhibition effect.In addition,PTX/CQE NPs could suppress lung metastasis of breast cancer.Hence,PTX/CQE NPs have a promising prospect in breast cancer therapy.