Fabrication And Application Of Antifouling Electrochemical Aptasensor Based On PANI,GO-PEDOT And L-Glu

In this thesis,a series of antifouling electrochemical aptasensors were constructed by using the conductive polymers,graphene oxide and L-Glutamic acid as the substrate materials,and using the peptides as the antifouling materials,which have achieved highly sensitive and specific detection of prostate specific antigens（PSA）and adenosine triphosphates（ATP）.At the same time,its potential for application in actual sample testing had also been explored.The thesis mainly includes the following three aspects:（1）Based on coral-like PANI-AuNPs composite materials and the peptides,the antifouling electrochemical aptasensor was constructed for detecting PSA.Firstly,coral-like poly-aniline（PANI）and gold nano-particles（AuNPs）were separately electrodeposited on glass carbon electrode（GCE）via the simple and controllable electrodeposited method,which can obtain the electrode modified with PANI-AuNPs composite material.Coral-like PANI not only can enhance the conductivity of GCE,but also can provide more active sites for the growth of AuNPs.Then,the peptides（CRERERE）were anchored on the modified-electrode to improve the antifouling ability.Finally,PSA aptamer and BSA were separately immobilized on the modified-electrode,and then the aptasensor was constructed.Based on the synergistic effect of the excellent conductivity and special morphology of the substrate materials,and the antifouling ability of the peptides,the aptasensor exhibited a wide linear range from 0.1 pg mL^-1 to 100 ng mL^-1,low limit of detection of 0.085 pg mL^-1（S/N=3）,a high sensitivity of 462.7μA·(ng mL^-1)^-1·cm^-22 and good antifouling performance.The aptasensor also possessed outstanding selectivity,admirable reproducibility and satisfying stability.Moreover,the aptasensor can directly detect PSA in 10%human serum solutions.The satisfying results provide a promising aptasensor for clinical analysis and diagnose in the future.（2）Based on GO-PEDOT composite film and the peptides,the antifouling electrochemical aptasensor was constructed for detecting ATP.Graphene oxide and poly（3,4-ethylenedioxythiophene）（GO-PEDOT）composite film,as substrate material,was synthesized on glass carbon electrode（GCE）by facile and controllable electrodeposition method,which can increase the conductivity of the modified-electrode and provide more active sites for peptide attachment.The zwitterionic peptide（EKEKEKE）not only can form antifouling layer on the surface of GCE/GO-PEDOT to resist nonspecific adsorption,but also can be as a mediator for aptamer immobilization.Combing GO-PEDOT composite film and zwitterionic peptide can make the aptasensor achieve more remarkable detection property.Aptasensor prepared under optimal conditions showed a wide linear working range from 0.1 pM to 1.0μM,a low detection limit of 0.03 pM（S/N=3）and high sensitivity of 2674.7μA·μM^-1·cm^-2.The aptasensor also exhibited outstanding selectivity,satisfactory reproducibility and desired stability for ATP detection.More important,the novel aptasensor can be used to directly detect ATP in 10%human serum solution,indicating its well potential for practical analysis of ATP in the future.（3）Based on poly L-Glu and the peptides,the sensitive electrochemical aptasensor was constructed for ATP detection.Poly L-Glutamic（poly L-Glu）as the substrate material was deposited on glass carbon electrode（GCE）via cyclic voltammetry.The prepared substrate material had a lamellar shape on GCE,which not only increased the conductivity of the modified electrode,but also increased the effective area of the electrode,and then provided more active sites for the immobilization of the aptamer.Then,the ATP aptamer and peptides were immobilized on the modified-electrode surface.The aptasensor showed a wide linear working range from 0.01 pM-1.0μM,a low detection limit of 0.01 pM（S/N=3）and a high sensitivity of 582.9μA·μM^-1·cm^-2.The aptasensor also exhibited outstanding selectivity,satisfactory reproducibility and desired stability for ATP detection.In addition,the prepared sensor still exhibited excellent detection performance for ATP in 10%serum samples,which proves its potential in practical application.