Research On Flexible Tri-Phase Interface Enzyme Electrode Construction And Biosensor Application

The development of highly sensitive biochemical molecular precision detection devices is essential for the accurate detection and treatment of human diseases.In recent years,scientists have combined flexible sensing technology and electrochemical enzyme sensing technology to develop a more portable flexible electrochemical enzyme sensor device.Such biosensors can be worn on the body and perform non-invasive and real-time monitoring of disease biochemical markers in body fluids.Since most of the enzyme sensors still use the first-generation enzyme electrode sensing mechanism,that is,oxygen is used as the electron acceptor,there are still many problems in the actual detection process.For example,the oxygen required for the enzyme-catalyzed reaction only comes from the limited dissolved oxygen in the solution to be tested,which greatly limits the catalytic kinetics of the oxidase and the upper linear limit and sensitivity of the sensory detection.Oxygen fluctuations cause kinetic problems in enzyme catalytic reactions and poor detection accuracy and reproducibility.Electrochemical detection of hydrogen peroxide needs a relatively higher oxidation potential,at which various electroactive substances can be oxidized,causing serious interference.Therefore,how to keep oxygen sufficiently constant during the detection process and avoid the interference of various electroactive substances is of great significance for the development of high-performance flexible electrochemical biosensor.In this paper,flexible electrode substrates with a super-hydrophobic property was prepared based on the synergistic effect between surface microstructure and chemical composition.Moreover,flexible oxidase enzyme electrodes with a gas-liquid-solid tri-phase reaction interface was constructed using these substrates,and their performance in biosensor was evaluated.The main research contents are as follows:Part I:Construction and performance of flexible tri-phase interface enzyme electrode.We prepared flexible superhydrophobic electrode substrates by constructing different types of surface microstructures on a low surface energy polydimethylsiloxane(PDMS)film using a template method.Based on these substrates,we further developed flexible gas-solid-liquid tri-phase interface enzyme electrodes by depositing the a conductive carbon nanotube network membrane,electrocatalysts and an oxidase enzyme layer on their surface.After that,we constructed flexible electrochemical biosensors by assembly tri-phase interface enzyme working electrode with a counter electrode and a reference electrode,and studied their detecting performances,such as the detection linear range(up to 60 mmol),accuracy(in the case of fluctuating oxygen content,the background current can always be kept constant),selectivity(strong anti-interference substance ability,and can be detected in the sweat of the environment)and mechanical stability(after hundreds of bendings,the detection ability is still good).Part ?:Application research of flexible tri-phase interface enzyme electrode.Based on the first work,we obtained a flexible superhydrophobic electrode substrate by modifying a porous polyethylene(PE)film that can be prepared uniformly at low cost and in large scale.Based on this electrode substrate,we further developed a tri-phase interface enzyme electrode by depositing a metal thin film,electrocatalysts and an oxidase layer on the surface.Using this tri-phase enzyme electrode,we constructed a biosensor and systematically studied their detection performance.The tri-phase interface enzyme sensor with PE film as the flexible substrate has the ability to resist oxygen fluctuations,and it can still keep the background current constant under the condition that the oxygen content continuously changes;and the anti-interference ability is strong,and it can still work normally in sweat containing many interfering substances;and it has a very high detection limit(30 mmol)and a very low detection limit(10 ?mol);the sensitivity is high(0.8?A/Mm);and the tri-phase interface enzyme sensor with PE film as the flexible substrate is universal.Changing the type of oxidase can detect different specific analytes and has good universality.Such improvements provide new technical routes and methods for the development and application of highly efficient flexible biosensors.