| Colon cancer is one of the most common malignant tumors with high cancer related mortality.Chemotherapy is still one of the most important treatments for adjuvant therapy after surgery and advanced tumor for now.Due to low targeted property,conventional drug distributed in the whole body,thus the therapeutic effect was unsatisfied and always accompanied with serious side effect.Furthermore,the defect in physicochemical property of clinical drug limited the therapeutic effect,such as the size of drug molecular,solubility,permeability,and stability et al.The use of polymer stereocomplex nanomicelle as nanocarrier for conventional chemotherapy drug could improve the targeted property and therapeutic effect,and decrease the side effect.What is more,through loaded chemotherapy drug into nanomicelle,the solubility,permeability and stability could be improved effectively.Therefore,polymer nanomicelle for drug delivery system provided new thought and opportunity for targeted therapy of malignant tumor.Objective:In this study,polymer stereocomplex nanomicelle was synthesis through nanotechnology,and decorated with c RGD as targeted ligand.DOX was capsulated into micelle as anti-tumor drug.Murine colon cancer cell C26 was used for establishing xenografted tumor model.Thetherapeutic effect and targeted property of nanomicelle in colon cancer treatment were evaluated through animal and cell experiments.Method:(1)4-arm PEG-b-PDLA,m PEG-b-PLLA and c RGD-PEG-b-PLLA were synthesized by ring-opening polymerization separately.Stereocomplex micelle(SCM)and cyclic(Arg-Gly-Asp-D-Phe-Cys)(c RGD)decorated micelle(c RGD-SCM)were synthesized by nanoprecipitation method subsequently,and doxorubicin(DOX)was encapsulated into the micelle.The physicochemical property was tested by1 H Proton nuclear magnetic resonance(1H NMR),transmission electron microscopy(TEM)and dynamic laser scattering(DLS).The in vitro DOX release from drug loaded micelle was also examined.(2)Murine colon cancer cell C26 was used as experiment cell.The uptake of tumor cell was detected by confocal laser scanning microscopy(CLSM)and flow cytometry(FCM).The anti-tumor effect in vitro of free DOX,SCM/DOX and c RGD-SCM/DOX were tested by 3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide(MTT)method.(3)The circulation time of DOX from free DOX,SCM/DOX and c RGD-SCM/DOX in vivo were detected by high-performance liquid chromatography(HPLC)method.In C26 xenografted tumor mice model,the distribution in tumor and major organs were tested by fluorescence image method.The anti-tumor effect of drug loaded nanomicelle in vivo was evaluated by observation and measurement of tumor growth and immunohistochemical method.Result:(1)During the research,our team successfully synthesized multicomponent polylactide stereocomplex micelle and c RGD decoratedSCM.Subsequently DOX was successfully encapsulated into SCM and c RGD-SCM.The drug loading efficiency of SCM/DOX and c RGD-SCM/DOX was 8.9 ± 0.37 wt.% and 8.4 ± 0.29 wt.% separately.SCM/DOX and c RGD-SCM/DOX presented spherical structure under TEM examination.The Dhs of SCM/DOX and c RGD-SCM/DOX was 91.6±4.9nm and 102.9 ± 5.6nm separately.The DOX release curve in vitro(PBS solution,p H=7.4,t=37.5?)presented a kind of initial quickly release followed with subsequently slow release pattern.(1)Compared with free DOX,SCM/DOX and c RGD-SCM/DOX showed improved uptake of colon cancer cell,and c RGD-SCM/DOX showed the best uptake efficiency.Through MTT test,c RGD-SCM/DOX showed the best anti-tumor efficacy in vitro.(2)Pharmacokinetics test result showed that,SCM/DOX and c RGD-SCM/DOX presented a slow release pattern in vivo.Compared with free DOX,DOX loaded nanomicelle prolonged circulation time significantly.Fluorescence imaging test showed a highest DOX concentration in tumor location in c RGD-SCM/DOX treated group,thus c RGD-SCM presented significant targeted property.(3)In the C26 xenograft mice model,c RGD-SCM/DOX significantly inhibited tumor growth,and Immunohistochemistry examination showed that,c RGD-SCM/DOX presented best efficacy in Proliferation inhibition of tumor and apoptosis compared with free DOX and SCM/DOX.At the meantime,both SCM/DOX and c RGD-SCM/DOX decreased the side effect on major organs of mice such as heart,liver,spleen,lung and kidney.Conclusion:In this research,our team designed and prepared 4-arm PEG-b-PDLA,m PEG-b-PLLA and c RGD-PEG-b-PLLA.These polymers composed PLA SCM,and marked as c RGD-SCM/DOX,which was used as targeted delivery of DOX.c RGD-SCM/DOX prolonged circulation time in vivo,improved the concentration in tumor location,enhanced anti-tumor effect for ?v?3 integrin positive colon cancer cell C26.In the nanomicelle,the targeted ligand of c RGD-PEG-b-PLLA could be facilely replaced according to different receptor of various tumor cells.Of cause,the targeted SCM could encapsulate and targeted deliver other chemical medicine.In the view of the above superior properties,targeted SCM may have great potential in clinical application of individual chemotherapy of various malignant tumors. |
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