Fabrication And Optimization Of Biomolecular Detection Electrode Based On ALD

Biomolecules play an important role in various life processes including human metabolism.The research and detection of biomolecules is of great significance for disease diagnosis and treatment.Electrochemical detection is a new type of detection and analysis technology that can achieve efficient,sensitive,fast and selective detection.The key is the manufacture and modification of electrode materials.In this paper,the design and process research of the composite deposition system was completed based on atomic layer deposition（ALD）technology.Au nanoparticles/Molybdenum disulfide/Fluorine doped tin oxide conductive glass（Au NPs/Mo S₂/FTO）electrodes were fabricated for the detection of biomolecules such as mi RNA-155 and BSA.The main research contents are as follows:（1）Design and process research of the composite deposition system based on ALD.The ALD-based composite deposition system independently designed and constructed by the laboratory was based on the self-limiting reaction mechanism of atomic layer deposition technology and combined the advantages of chemical vapor deposition（CVD）technology.It was mainly composed of reaction chamber,pipeline system,heating system and exhaust gas treatment system.The process and parameters can be adjusted in the reaction chamber according to the requirements for depositing two-dimensional thin film materials and can realize ALD self-limiting reactions,CVD-like reactions,and high-temperature annealing.（2）Manufacture of biomolecular detection electrode based on ALD.Au NPs/Mo S₂/FTO electrodes were fabricated by using ALD technology and electrochemical deposition.A series of characterization analysis and electrochemical performance were performed on the electrodes.It was found that the morphology,thickness,size and distribution of Mo S₂ nanofakes can be regulated by controlling the number of ALD cycles.Cyclic voltammetry and electrochemical impedance spectroscopy showed that Mo S₂had poor electrical conductivity.The functionalization of Mo S₂ by Au NPs can accelerate the electron transfer greatly.Chronocoulometry proved indirectly that ALD-made Mo S₂ had a large specific surface area.These results demonstrated the successful fabrication of the Au NPs/Mo S₂/FTO electrode for the biomolecular detection.（3）Electrode performance optimization and biomolecular detection based on ALD.The ALD-based electrode performance and experimental conditions were optimized by using cyclic voltammetry.The mechanisms of electrochemical detection of the mi RNA-155and BSA were analyzed.Under the optimum manufacturing parameters and experimental conditions,the Au NPs/Mo S₂/FTO electrode can detect mi RNA-155 from the range of 1×10^-15 M to 1×10^-8 M and the detection limit is 0.32 f M.The detection of BSA was ranging from 0.25μM to 2.0μM with a detection limit of 0.08μM.It showed good sensitivity,selectivity,repeatability and stability,and the serum sample experiment also proved the potential application value of the detection electrode.