Study On Nano-targeting Drug Delivery System With Multifunction Based On Self-assembly Through Disulfide Bond

There are more and more researches on nano drug delivery system in recent years,its good targeting,diverse functions have been widely recognized compared with the conventional drugs.But there are still many shortcomings with the nano drug delivery system,such as the poor biocompatibility and serious side effects of the nanocarrier.Small molecule self-assembly nano drug has been paid more and more attention because it can avoid the introduction of the polymer carrier and thus reduce the side effects of the drug delivery system.The insertion of a single disulfide bond into hydrophobic molecules will self-assemble into stable nanoparticles as the disulfide bond can balance the competition between intermolecular forces involved in the self-assembly of nanomedicines according to some reports.Besides,the disulfide bond itself has redox-sensitivity,which can quickly release the drugat the presence of reducing glutathione.But,at present the tumor cell killing effect of the antitumor drugs is limited.One of an important reasons is that the tumor cells can protect themselves through autophagy under the stimulus of chemotherapy drugs,which lead to poor drug efficacy,and high tumor recurrence rate.In the treatment of tumor,hydroxychloroquine is often used to combine with some chemotherapy and radiotherapy drugs toenhance the tumor lethality because it can interrupt the tumor self-protection pathways by inhibiting the integration of autophagosomes and lysosomes.Compared with the single chemotherapy,the combination of chemotherapy and hyperthermia will lead to better treatment effects.Indocyanine green is the near-infrared optical diagnostic reagentapproved by FDA.It not only has good optical imaging function,but also has excellent photothermal conversion efficiencyunder the near infrared laser irradiation,which can make the tumor local temperature increased and kill cancer cells.In this work,the doxorubicin(DOX)and hydroxychloroquine(HCQ)were chemically linked by the insertion of a single disulfide bond,and the successful synthesis of the product(DOX-SS-HCQ)was confirmed by a series of characterization such as UV-Vis spectroscopy,nuclear magnetic resonance spectroscopy,transmission electron microscopy and molecular dynamics simulations.After this,the indocyanine green was loaded followed by the PEGylation of the system.Thus,a kind of self-assembled multi-functional nano-targeting drug delivery system(ICG/DOX-SS-HCQ/DSPE-PEG-FA)combining chemotherapy,hyperthermia,redox-sensitivity and optical imaging was successfully established.Then the size distribution was measured as 135 nm and zeta potential of nanoparticles as-22 mv.The results of in-vitro release and photothermal conversion efficiency of nanomedicines showed that the preparation was able to rapidly release the drug under reduced glutathione and had good photothermal conversion efficiency under near infrared laser irradiation.The results of cell uptake confirmed that the nanomedicines loaded with folic acid could enter the cells rapidly through the folate receptor-mediated endocytosis pathway on the surface of MCF-7 cancer cell membrane.And in the cytoplasm,the redox-sensitive disulfide bond ruptured quickly to release free doxorubicin and further played a role of killing cancer cellsat the nucleus with the presence of glutathione.The cytotoxicity of nanomedicines to MCF-7 cells showed that the cytotoxicity of nanomedicines was significantly enhanced compared with that of doxorubicin,and the cytotoxicity of nanomedicines was more remarkable after laser irradiation.Immunofluorescence assay showed that HCQ could effectively inhibit autophagy and enhance the therapeutic effect of doxorubicin.These results suggested that the nanomedicines combining chemotherapy and hyperthermia can be rapidly uptaken by MCF-7 cells in vitro and produce greater toxicity.The results of in-vivo imaging experiments showed that the nano-drug delivery system had a longer residence time in the body and more accumulation in the tumor site than the free indocyanine green,indicating that the drug delivery system had a longer half-life and a better tumor targeting.Nude mice pharmacodynamics results showed that compared with doxorubicin,nanomedicines group can effectively inhibit tumor growth.Especially after the use of laser irradiation,the tumor volume decreased by 68%.Tunel staining results also showed that nanomedicines with laser irradiation group could lead to more cell apoptosis,indicating that the nano-drug system can effectively inhibit tumor growth and produce a good therapeutic effect.The results above showed that the ICG / DOX-SS-HCQ / DSPE-PEG-FA nano-drug system was a kind ofnew drug delivery system combining glutathione-responsivity,optical imaging,targeting,chemotherapy and hyperthermia,which might has a good application prospectsin the treatment of cancer.