| Compared with traditional materials,polypeptide-based materials obsess better compatibility and degradability for the requirement of the biomedical applications.We studied the photoresponsiveness and self-assembly behavior of polypeptoids synthesized by ring opening polymerization.In addition,the amphiphilic oligopeptide was used as the gelator to obtain the hybrid hydrogels by adding additives.This dissertation includes the following three parts:1.Synthesis of photoresponsive polypeptoids containing o-nitrobenzene group in side chains: The photoresponsive polypeptoids was first synthesized by ring opening polymerization with molecular weight distribution less than 1.19.This indicates that the ROP of the copolymer is well-controlled.After UV irradiation,o-nitrobenzene group was cleaved,and the reaction process can be monitored by UV spectra.The photocleavage ratio of o-nitrobenzene groups with different UV irradiation time can be calculated by NMR.2.Self-assembly of photoresponsive polypeptoids containing o-nitrobenzene group in side chains: The diblock copolypeptoid with different chain lengths of hydrophobic blocks can self-assemble into various morphologies,including spheres,short cylinders and vesicles.The thiol groups can be generated by the UV-irradiation and can be spontaneously oxidized into disulfide bonds to stabilize the nanostructure.Further the oxidation process is reversible in the presence of the reductive reagent,resulting in dynamic and reversible self-crosslinking assemblies.3.Study on polypeptide gelator: The hybrid hydrogels were obtained by adding additives into the amphiphilic oligopeptide that behaves as a gelator.The property of the hybrid can be modified by the interaction between the additives and oligopeptide.The rheometer was used to study the strength of the hybrid hydrogel.The morphology of nanostructure were further investigated by transmission electron microscopy and scanning electron microscopy. |
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