Fabrication And Application Of Electrochemical Biosensors Based On Functional Polymer

In this thesis,different functional polymer composites were prepared using different method.Based on these composites,several electrochemical biosensors were constructed for the sensitive and selective detections of different disease biomarkers.The microstructures and biosensing performances of these nanocomposite modified electrodes were characterized with various technologies,such as EIS,CV,DPV,SEM and XPS.It is expected that these novel biosensing platforms may find potential applications in clinic diagnosis.The main research contents of this thesis are summarized as follows:(1)We describe an electrochemical aptasensor for thrombin that is based on the use of a glassy carbon electrode(GCE)modified with polydopamine that is loaded with silver nanoparticles(PDA/AgNP).The use of AgNPs improves the conductivity of the film and increases the surface area of the GCE.PDA was deposited on the GCE via self-polymerization,and the thrombin binding aptamer was grafted onto the PDA modified GCE by a single step reaction.Residual electrode surface was blocked with 6-mercapto-1-hexanol.On exposure to thrombin,the electrochemical impedance of the modified electrode increases gradually.Response is linear in the 0.1 pM to 5.0 nM thrombin concentration range,and the limit of detection is as low as 36 fM.The method is selective and capable of detecting thrombin in diluted human serum.In our perception,such a GCE modified with AgNPs in a PDA matrix may be applied to many other analytes for which appropriate aptamers are available.(2)Detection of disease biomarkers within complex biological media is a substantial outstanding challenge because of severe biofouling and nonspecific adsorptions.Herein,a reliable strategy for sensitive and low fouling detection of a biomarker,thrombin(TB),in biological samples was developed through the formation of a mixed self-assembled sensing interface,which was constructed by self-assembling hyaluronic acid(HA)and TB aptamer onto the self-polymerized polydopamine modified electrode surface.The developed aptasensor exhibited high selectivity and sensitivity toward the detection of TB,such as wide linear range and low detection limit(0.034pM).Moreover,owing to the presence of HA within the sensing interface,the aptasensor in complex biological media such as human serums with significantly reduced nonspecific adsorption effect.(3)Flexible sensors that can bend and conform to underlying curvedor uneven surfaces,while retaining their intrinsic performance,areessential to develop high-performance wearable sensors for personal healthcare.In this work,polypyrrole-polyethylene glycol(PPy-PEG)flexible composites were prepared using electrochemical polymerization method,and PPy-PEG flexible material has good flexibility and conductivity.Based on PPy-PEG flexible materials,we constructed dopamine(DA)and adenosine triphosphate(ATP)biosensor,which showed excellent electro-catalytic activity toward the redox of dopamine,and good selective of detecting ATP.Finally,the PPy-PEG flexible materials can be used in flexible supercapacitors,which can delivering high specific capacitance.