Research On The Construction,Mechanism And Performance Of MoS₂ Based MiRNA Sensors

In modern society,malignant tumor is one of the diseases which threat to human health seriously,specifically lung cancer with the highest incidence and mortality.Compared with traditional detection methods,detecting the biomarker miRNA has the higher accuracy,faster operation and lower cost to identify the course of cancer.The rapid and sensitive detection of miRNAs is promoted by the huge development of nanomaterial-based electrochemical biosensing technology.This thesis will study nanomaterials based on MoS₂,introduce them into the construction of sensor platforms,develop biosensors that can be used for lung cancer-related miRNA detection,and explore the detection mechanism in depth to promote the optimization of sensor performance and achieve sensitive detection of lung cancer related miRNA:(1)Preparation of MoS₂-based nanomaterials and related electrodes.A single-component MoS₂ thin film was prepared by ALD technology,and related electrodes were prepared by thin film transfer method.The continuity and uniformity of the thin film before and after the transfer were proved by light microscope characterization;MoS₂/Ti₃C₂ composite nanostructures were prepared by hydrothermal synthesis technology,and related electrodes were prepared by the drop casting method.The nanostructures on the surface of the constructed electrode and the distribution of Au NPs were analyzed by TEM photos.Comparing both of their electrochemical CV and EIS characterization,the working electrode prepared based on the MoS₂/Ti₃C₂ composite nanostructure exhibits better performance,so this scheme is selected to continue in-depth research;SEM,TEM,XRD,and XPS are used to conduct a comprehensive morphology and component characterization analysis of the selected MoS₂/Ti₃C₂.(2)Construction of the sensor platform and in-depth research on the detection mechanism.The construction of the miRNA sensor platform based on MoS₂ was completed by the drop casting method,and its construction process was characterized by XPS and electrochemical platform.The experimental results show that the designed electrode has good physical adsorption stability and electrochemical stability.The construction mechanism of the constructed miRNA sensor is discussed in detail with the morphology and component characterization data.The XPS spectra before and after the detection showed that the proportion of Au-S bonds in the Au element on the electrode surface decreased from 20.31%to 13.30%.Based on this,combined with changes in the DPV signal,the detection mechanism of the constructed miRNA sensor was proposed.(3)Optimization of sensor platform and establishment of sensor detection map.By optimizing the sensor platform,the optimal detection environment is 1.5 mg/m L for MoS₂/Ti₃C₂ concentration,1.0×10^-9 M for ssRNA concentration,and 37? for the hybridization temperature of ssRNA and target miRNA.The linear detection range of the constructed miRNA sensor for miRNA-182 obtained in the detection environment is:1 f M to 0.1 n M.The regression equation is obtained:y=296.4+10.77lg(x)(R²=0.987)through linear fitting of the DPV response signal.The minimum detection limit of the sensor is 0.43 f M based on the calculation principle of X+3?.(4)Sensor performance evaluation and application exploration.The specificity of the miRNA sensor was studied:the signal intensities of the single-base mismatch and three-base mismatch were about 75%and 16.7%of the fully complementary paired sequences,respectively.The storage stability of the sensor at 4? was explored:after 2days and 8 days of storage,the signal intensity loss was about 3%and 17%,respectively.Through spike detection in the actual serum,a recovery rate of 92 to 105%was obtained.Finally,the designed sensor showed a spike recovery of no more than±10%by detecting mixed samples containing miRNA-182 and miRNA-155,demonstrating the practical application value of the constructed miRNA sensor.The miRNA sensor based on the MoS₂/Ti₃C₂ nanocomposite structure can achieve sensitive and rapid detection of miRNA.Furthermore,this thesis demonstrates the detection mechanism of electrochemical sensors from the microscopic change of charge.In addition,this paper comprehensively evaluates the performance of the constructed miRNA sensor and makes a preliminary exploration for its practical application.