The Construction And Properties Of Biosensing Interfaces Based On Antifouling Materials

Biofouling is a common problem in many fields,such as biosensors,drug delivery and implants.Biofouling mainly refers to the non-specific adsorption of proteins and cell adhesion for biosensor,and it can seriously affect the performance of biosensors.Therefore,it is of great significance to construct antifouling biosensing interfaces to reduce the non-specific adsorption of proteins,so as to achieve accurate and sensitive detection.Generally,the antifouling material can form a hydration layer on the surface of the substrate and therefore inhibit the non-specific adsorption of proteins and cell adhesion.In this thesis,different antifouling materials including cysteine,peptide and zwitterionic polymer,were used to construct various biosensing interfaces for the nonfouling detection of biomarkers.The main research contents are as follows:?1?A simple and highly selective biosensor was successfully developed for the detection of immunoglobulin E?IgE?by using cysteine as an antifouling material.First,the 3,4-ethylenedioxythiophene?EDOT?and glycine?Gly?were electrodeposited onto the surface of a glassy carbon electrode to obtain the Gly/PEDOT composite.The composite possesses rough microstructure,which can increase the specific surface area for the modified electrode.The antifouling material cysteine and IgE aptamer were then immobilized onto the Gly/PEDOT composite,and the biosensor for IgE was thus constructed.The prepared IgE biosensor showed a linear range of 0.01-100 ng/m L,with a detection limit of 0.01 ng/m L.The biosensor showed good antifouling ability,and it was able to effectively inhibit the non-specific adsorption of proteins in 2%human plasma samples,demonstrating promising potential for clinical application.?2?An antifouling biosensor for ATP was developed through the self-assembly of peptide and ATP aptamer onto the gold nanoparticles?AuNPs?modified electrode surface.AuNPs were electrodeposited on the surface of a gold electrode,so as to increase the specific surface area of the gold electrode and provide more binding sites for the immobilization of peptide and aptamer.The ATP biosensor was constructed by one-step self-assembly of the antifouling peptide and ATP aptamer onto the AuNPs-modified gold electrode through the formatin of the Au-S bonds.Owing to the presence of peptides,the hydrophilicity of the biosensing interface was significantly improved,which can effectively inhibit the non-specific adsorption of protein for the detection of target ATP in 1%human plasma.The aptasensor based on ATP aptamers and zwitterionic peptides exhibited a linear range of 0.1 pM-5.0 nM,with a detection limit of 0.1 pM.Moreover,the aptasensor exhibited excellent selectivity and stability.?3?A zwitterionic compound as the antifouling material was synthesized through the reaction of 1-vinylimidazole with bromoacetic acid,and based on this material,an electrochemical antifouling biosensor for BRCA1 was developed.The initiator was firstly introduced onto the gold electrode surface through the formation of Au-S bond to make the gold electrode surface rich in bromine?-Br?.Using the SI-ARGET ATRP reaction,the zwitterionic polymer monomer was grafted onto the gold electrode to form antifouling surface.The carboxyl group?-COOH?on the antifouling interface was then used to immobilize the aminated biomolecule?recognize BRCA1?for the detection of the target BRCA1.The constructed electrochemical biosensor exhibited excellent sensing performance and had a linear detection range from 10^-15 mol/L to 10^-8 mol/L for the target.Most interestingly,the biosensor showed superior antifouling ability even in 5%human serum samples,and in this case the signal change rate maintained within 3.5%.