| The multiple stimuli-responsive amphiphilic polymer can response to umber stimuli,and with the variation of the structure of sensitive groups of polymer,the amphipathicity of polymer will be diversity.As the multiple stimuli-responsive polymer can adapt to the complicated change and the multiple demanding of the environment,it`s much more suitable for the application in realistic environment.With the Fc to Fc+ transformation of ferrocene(Fc)group while exposed to redox agents,the hydrophilic of Fc will be great changed.The azobenzenen(Azo)moieties can undergo reversible trans-to-cis photo-isomerization,which will result in a change of hydrophilic-lipophilic balance.In addition,due to the host-gust effect between the ?-cyclodextrin(?-CD)and Fc/Azo,the ?-CD will package or dispackaged the Fc/Azo group,leading the variation of the amphipathicity of polymer.In the paper,we have designed and synthesized a novel dual stimuli-responsive amphiphilic polymer(FcC11AzoPEG)which composed by the hydrophilic PEG5000 block and the hydrophobic block(FcC11AzoCOOH).We have studied the stimuli-responsive self-assemble behavior and the host-gust self-assemble behavior of FcC11 AzoPEG.In addition,the stimuli-responsive self-assemble property was applied to the controlled drug release system.In the second chapter,we introduced the synthetic progress of the FcC11 AzoPEG.For each compounds in the synthetic progress,the TLC,FT-IR and NMR was used to characterized and determine the structure of molecules.According to the result of characterization,we have successfully synthesized the target compound FcC11 AzoPEG,which will provided the components for future study.In the third chapter,we have studied the stimuli-responsive self-assemble property of FcC11 AzoPEG.At first,the FT-IR was used to study the reversible stimuli-responsive behavior of Azo and Fc.The result of FT-IR indicated that Azo and Fc group affords the polymer a dual stimuli-response: i.e.,a slow photo-response and a fast redox-response..The CAC values and the diameter of micelles increase gradually with the hydrophilicity of polymer in the order: FcC11 AzoPEG < FcC11cis-AzoPEG < Fc+C11AzoPEG < Fc+C11cis-AzoPEG,which was corresponding to the stimulus of initial,UV,oxidation,UV+oxidation.Owing to the gradual change of the HLB of polymer while exposed to different stimuli,the rate and amount of drug release from R6G-loaded micelles could be efficiently adjusted under different stimuli: slow release rate and low amount of release after UV irradiation,fast release rate and medium amount of release after oxidation by Fe2(SO4)3,and high amount of release after a combined stimulation of UV irradiation and oxidiation reaction.Compared to normal drug release system,this rate and amount controlled system was more suitable for the treatment of different demands of illness.In chapter 4,we have studied the host-gust self-assemble property of the FcC11 AzoPEG and ?-CD.After the addition of ?-CD into the solution of FcC11 AzoPEG,the ?-CD will package the Fc group by the host-gust effect between them,we called the Fc packaged polymer ?-CD/Fc.Interestingly,due to the rigid property of Azo group and the hydrogen-bond interaction between ?-CD,the ?-CD/Fc polymer will self-assembled into regular nanofiber micelles.Furthermore,with the oxidation of Fc group,the ?-CD will dispackaged the Fc+ group.For one hand,some of ?-CD will leave the FcC11 AzoPEG,recovered to the initial spherical micelles.For another hand,some of ?-CD will turned to package with Azo groups,those polymer called ?-CD/Azo.With the charge repulsion of Fc+ groups,the cavity of nanofiber will swelling,which will result to the formation of fusiform micelles.Then,while the ?-CD/Azo polymer was exposed to UV irradiation,the ?-CD will dispackaged with cis-Azo,and turned to package with PEG(?-CD/PEG).The ?-CD/PEG will self-assembled into spherical micelles. |
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