Preparation Of Glucose-Responsive Starch Nanoparticles And Their Application In Insulin Controlled Release

In this thesis,a series of oxidized starch polymers with glucose responsive behavior were synthesized and employed as drug carriers.The structure of the oxidized starch polymers was characterized by ~1H NMR and FTIR.Their critical micelle concentration,morphology and size were examined using TEM and DLS.Meanwhile,the stability and glucose responsive performance of the carriers were studied.The blood compatibility and cell toxicity were determined by hemolysis test and MTT method,respectively.The drug-carriers have the potential in applicability of glucose-responsive material for insulin and nattokinase delivery.The main results were shown as follows:1.A novel amphiphilic glucose-sensitive oxidized starch polymers(mPEG-DAS-APBA)containing 3-aminophenylboronic acid(APBA)and mPEGylated oxidized starch(mPEG-DAS)was synthesized with different degrees of oxidation.The polymer could self-assemble into mPEG-DAS-APBA micelles with“shell-core”structure in PBS solution.mPEG-DAS-APBA micelles with oxidation degrees of 20%,40%and 60%were prepared.The results displayed that40%m PEG-DAS-APBA micelles had low cytotoxic activity and showed notable glucose responsive behavior,releasing insulin rapidly at the condition of 2 mg/mL of glucose at pH 7.4.2.An amphiphilic glucose-sensitive oxidized starch polymers(mPEG-DAS-APBA-Cou)containing APBA,m PEG-DAS,hydrophobic 7-hydroxycoumarin-4-acetic acid(Cou)were synthesized.This oxidized starch could self-assemble into mPEG-DAS-APBA-Cou micelles with“shell-core”structure in PBS solution.The drug-loaded micelles can release insulin fast once hyperglycemiainaphysiologicalenvironment.Theresultsdisplayedthat mPEG-DAS-APBA-Cou micelles had low cytotoxic activity and showed notable glucose responsive behavior,releasing insulin rapidly at the condition of 3 mg/mL of glucose at p H 7.4,while comparatively inert release at 1 mg/mL glucose(pH 7.4).The insulin release from the nanocarriers is senstive to the concentration of the glucose.Therefore,the amphiphilic mPEG-DAS-APBA-Cou micelles have the potential in applicability of glucose-responsive material for insulin delivery.3.A novel zwitterionic oxidized starch-based micelles with glucose-responsive behavior were developed.Insulin release from the nanocarriers is sensitive to the different concentration of the glucose,rapidly at the condition of 3 mg/mL of glucose at p H 7.4.MTT assay confirmed that zwitterion micelles were cytobiocompatible and low cytotoxic activity.The oxidized starch micelles had“stealth”characteristic against immune system due to zwitterion-functionalization.For comparison,PEGylation micelles were also synthesized.Confocal laser scanning microscopy(CLSM)and flow cytometry results displayed that PEGylation and zwitterion coating micelles have different recognition processes in contact with macrophages.After 4 h,Dox fluorescence of the Dox-loaded mPEG-DAS-APBA micelle groups were mostly located in nuclei.However,SB-DAS-APBA micelle groups were slightly detected in both nuclei and cytosol.In addition,the fluorescence signals of mPEG-DAS-APBA micelles showed enhanced trend than that of SB-DAS-APBA micelles in macrophage cells.These results suggest that,as drug carriers,zwitterionic self-assembled micelles SB-DAS-APBA not only possessed glucose-responsive insulin delivery property,but also reduced macrophage response performance.4.Zwitterionic oxidized starch-based micelles SB-DAS-VPBA with glucose-responsive behavior were developed by SET-LRP reaction.The novel chitosan-based hydrogel cross-linked dialdehyde starch derivative micelles(SB-DAS-VPBA),micelle-formed by self assembly with significant glucose responsiveness,was prepared by Schiff-base bonds with chitosan(CS).The gel formed by CS cross-linked SB-DAS-VPBA micelles,as a dual carriers delivery system,can release behavior of dual protein drugs(insulin and Nattokinase)independently,and possess thrombolysis effectively(p H 7.4).Cytocompatibility of the gel was examined by cell viability and hemolysis tests.These results suggest that,as drug carriers,chitosan-based hydrogel cross-linked dialdehyde starch derivative micelles not only possessed glucose-responsive insulin delivery property,but also owned good thrombdytic effect.