The Construction And Application Research Of Biological Sensors Based On Self-assembled Biomimetic Vesicles Technology Of Polydiacetylene (PDA)

Polydiacetylene (PDA) vesicles as a lipidosome have comparability and affinity with biological membrane Cell membrane. And which has been used to simulate the cell membrane artificially and construct the biosensors to the detection of biological active substances and environmental pollutants. In this thesis, PDA vesicles had been applied to constuct the biomimetic biosensors with high sensitivity and high selectivity. The thesis contained four chapters:In chapter one, the concept about PDA vesicles, such as the classification of the imitation of biological membrane, the self-assembly technology of vesicles and the characterization and the application of vesicles were simply overviewed. The purpose and the content of this thesis were pointed out also.In chapter two, a visual immune biological sensors for H5N1 virus based on PDA vesicles had been developed. The PDA vesicles could combine with the antibodies of H5N1 and form vesicles-antibody polymer. When the target H5N1 virus antigen were added into the above solution, the specific immune response between the antibody and antigen occured, which disturbs the skeleton structure of conjugated polymer of PDA molecular and then the solution color would turn from blue to red. Based on which, a simple biosensor for H5N1 virus detection had been developed with the linear range of 20～100 ng/mL and the detection limit of 6 ng/mL.In chapter three, a fluorescent biosensor for carcinoembryonic antigen (CEA) detection had been developed based on the luorescence resonance energy transfer (FRET) between the PDA vesicles polymer and the gold nanoparticles. Firstly, the PDA vesicles polymer and gold nanoparticles were modified with DNA fragments which can partly hybridize with the CEA aptamer. And a sandwich-like structure can be formed after the addition of CEA aptamer. At this stage, the fluorescence of PDA visicles can be quenched by the gold nanoparticles. In the presence of CEA, the CEA aptamer would bind to its target and cause the collapse of sandwich-like complex, leading to the recovery of fluorescence. Due to the high affinity and high specificity of aptamers, a sensitive and selective biosensor for CEA detection can be developed. This method showed wide linear ranges of 0.1～10 nM with a detection limit of 0.07 nM.In chapter four, a fluorescent biosensor for thrombin based on PDA vesicles had been proposed. Firstly, PDA vesicles were modified with thrombin aptamer, and the aptamer can form a special ligand structure-G-quadruplex when binded with its target. This combination could disturb the skeleton structure of conjugated polymer of PDA molecular, then the solution color would turn from blue to red. Since the G-quadruplex structure have activities like DNA enzyme, it could combine with hemin and catalytic H2DCFDA-H2O2 reaction to generate a strong fluorescence. The fluorescence intensity of the system has a relationship with the thrombin concentration with the linear range of 1～ 50 nM, the detection limit is 0.4 nM.