Construction And Application Research Of Antifouling Electrochemical Biosensor

In recent years,with the increase of work and life pressure,various diseases have seriously affected the human health life.Faced with this challenge,a variety of advanced health monitoring methods have emerged,among which electrochemical biosensors are widely used because of their convenient operation,simplicity,low cost,fast detection speed and high sensitivity.Based on the different recognition components,electrochemical biosensors can be divided into aptamer sensor,immunosensor,enzyme sensor and microbial sensor.Traditional electrochemical biosensors are easily contaminated by complex media such as serum.Hydrogels are widely used because of their three-dimensional porous structure,easy preparation,hydrophilic properties,biocompatibility and other advantages.By integrating hydrogels with conductive materials and antifouling materials,they can be used to detect small molecules in complex biological media while improving conductivity.This thesis is mainly divided into the following four parts:Chapter 1:IntroductionIn this paper,the concept,classification and research status of electrochemical biosensors are reviewed.The research progress of electrochemical biosensors and their applications in biological small molecules and clinical detection are mainly summarized.Chapter 2:Ultra-sensitive detection of ATP by antifouling electrochemical biosensor based on DNA scaffold conducting hydrogelAs an energy supplier,ATP plays an important role in various life activities.It is urgent to develop an effective detection method,however,traditional sensors face serious non-specific adsorption problems.In this work,an antifouling electrochemical biosensor based on the interpenetrating network of Y-DNA scaffold and polyaniline hydrogel was designed for ATP detection.Polyaniline hydrogels are conducive to the transport of electrons and ions,and the Y-DNA structure crosslinked by ATP aptamer achieves signal amplification effect in polyaniline hydrogels.Further synergistic antifouling effect is exerted by doping superhydrophilic cellulose nanocrystals（CNC）and zwitterionic polypeptide sequences（Pep）.The constructed hydrogel sensor was used for ATP detection,and the results showed that it had a wide linear range（0.1 p M～1μM）and a low detection limit（0.025 p M）（S/N=3）.In actual serum samples,the recovery rate of the sensor is 99.5～106%with relative standard deviation of0.40～2.88%.The experimental results show that the sensor has good ATP detection performance,and has certain reference value for the detection of other small biological molecules.Chapter 3:Construction of TiO₂-Ag/hydrogel electrochemical biosensor for antifouling detection of serotoninIn this work,based on the recognition and binding ability between neurotransmitters and their aptamers,titanium-silver nanoparticles were used as the base material,poly（vinyl phosphate-betaine sulfonate-glycyl methacrylate）（P（VPA-SBMA-GMA））hydrogel was used as the antifouling and fixed aptamer material,an antifouling electrochemical sensor for the detection of 5-hydroxytryptamine（5-HT）targets was constructed.Firstly,the photocatalytic activity of TiO₂-Ag nanocomposites is used to form P（VPA-SBMA-GMA）hydrogel antifouling layer by in-situ polymerization on its staggered surface.Among them,phosphorus-oxygen covalent bonds and hydrogen bonds are formed between titanium dioxide and vinyl phosphoric acid,which fix the hydrogel on the surface of the substrate material without affecting the original form of the substrate material.Betaine sulfonate is introduced as an antifouling material,and the ring-opening reaction of glycidyl methacrylate with amino groups is further used to introduce an aptamer with an end of modified amino group on the sensor surface,which is used for fixing the aptamer on the electrode surface for the specific binding of the target.The sensor has a wide detection range（0.5 p M～100 n M）and a low detection limit（5 f M）for 5-HT.The results show that the antifouling electrochemical sensor has good antifouling performance in complex biological media,and has excellent application prospects in the detection of neurotransmitters.Chapter 4:Anti-fouling detection of ATP by electrochemical sensor based on BSA-AgNWs hydrogelFirst,BSA-AgNWs hydrogels were formed from the mixed solution of bovine serum albumin-silver nanowires（BSA-AgNWs）under the crosslinking action of glutaraldehyde.Then,the gold is electrochemically deposited on the surface of the glassy carbon electrode,Au-S bond is formed between BSA and the gold electrode to bind the hydrogel material to the electrode surface.BSA can be used to prevent the adsorption of non-specific proteins on the sensor surface,AgNWs enhances the transfer of electrons from the hydrogel to the electrode surface,improving electrical conductivity,in addition,BSA contain abundant active sites and can be further functionalized by binding amino modified aptamers on the surface of hydrogels for antifouling detection of target objects.When the target appears,the aptamer can specifically capture the target,thereby causing a change in the electrochemical signal,which can be used for effective detection of ATP through the correlation between the electrochemical signal and the concentration of the target.The results show that the antifouling sensor has a wide linear range（1 p M～100 n M）and a low detection limit（0.19 p M）for ATP detection.The sensor can provide a certain reference value for the antifouling detection of other biological small molecules.