Research On Electrochemical Biosensor Based On Ce-MoS₂/AgNRs Nanocomposites And Scrcen-printed Three Electrodes System

With the development of science and technology, food safety,environmental monitoring and medical diagnosis areas have made rapid progress. Therefore, there is an increasing demand for low-cost, simple,sensitive and convenient sensors suitable for on-site real-time detection.Electrochemical biosensors have been developed rapidly and have made remarkable achievements. They can convert biomarker signals at molecular level into electrical signals, which has the advantages of rapid and sensitivity.Screen printing electrode?SPE? has the advantages of simple, low cost, and mass production, and disposable which avoids the interference between different samples. SPE is the carrier of electrode modification and the core of electrochemical biosensor. The preparation of basic electrode with excellent performance is the first step to construct electrochemical biosensor. In addition,the preparation of electrode materials to better promote the electron transport is also an important issue in the current research of electrochemical biosensor.In this paper, electrochemical biosensors were fabricated on the basis of the printing of three electrodes system with excellent electrochemical performance and the preparation of nanocomposites with good electrical conductivity. And made it applied in the basic detection and analysis of prostate specific antigen?PSA?.Firstly, the preparation technology and parameters of the screen-printed three electrodes system were optimized. The electrodes were fabricated on flexible PET substrates with which contact angle of water is 52.5°. The conditions of the grinding of the carbon paste were controlled at the level of400r/min and 20 min. The parameters of the geometry of the electrodes were as follows: the diameter of working electrode was D=3mm, the diameter of reference electrode was D= 1mm, the distance between working electrode and auxiliary electrode is eaqual to the distance between working electrode andreference electrode which is 1mm, the newly printed SPEs are pretreated in3 M Na OH solution for 60 min. Under these conditions, the base SPE has excellent electrochemical properties.Then, a single or several layers of circular ce-MoS₂ nanosheets with diameter about 3.5?m were prepared by the method of intercalation of lithium ions and subsequent exfoliated in the water solutions. AgNRs with regular morphology were prepared by a method of modeless and seedless. The mean diameter is about 39.54 nm and the average aspect ratio is about 19.67. The nanocomposites were formed by physical adsorption and electrostatic interaction, which with synergistic effect and can improve the electrochemical response of SPEs. And its conductivity is about 1.5 times of the sum of each single material.Finally, the PSA/BSA/anti-PSA/ce-MoS₂+AgNRs/SPE biosensor system was constructed with a stable and reversible base SPE and an excellent conductivity material of ce-MoS₂/AgNRs, which with the detection range was0.1¹000ug/mL, the sensitivity was about 0.019?A/?ng/m L? and the detection limitation of PSA was about 0.051ng/mL, and which with good stability and specificity. All that can fulfill the detection requirement of PSA in the diagnosis and screening processes of PCa.