Paper-based Electrochemical Sensor Constructed By High Catalytic Activity Metal Nanomaterial

The electrochemical biosensor is a kind of biosensor that uses an electrode as a signal converter,a biological substance as a sensitive component,and a voltage or a current as a detection signal.Electrochemical biosensors can increase sensor selectivity by controlling electrode potential.It also combines the selectivity of the chemical reaction of the surface material with the high sensitivity of the assay.Therefore,we can be considered that the electrochemical biosensor is an ideal system that combines separation,enrichment and selective measurement.It has unique advantages in improving selectivity and sensitivity.The method has the advantages of low background signal,high sensitivity,simple equipment and fast response.Therefore,it has received extensive attention in the fields of chemical sensing,biological analysis and environmental detection.In this paper,a high catalytic activity nanomaterial was used as catalytic material,and combined with the research of the research group on the lab-on-paper device.The paper-based electrochemical sensor was constructed to achieve the sensitive detection of cancer markers?microRNA?and the analysis of cancer cells?MCF-7?.The main research work is as follows:?1?Research on MicroRNA electrochemical paper-based sensors constructed of metal organic framework materials.Gold nanoparticles are grown on paper by in situ growth to enhance the conductivity of the substrate.The functionalized metal organic framework catalytic material is synthesized by hydrothermal method.The catalytic material is connected to the modified electrode through a chain displacement reaction of the target.The cyclic process of the target can result in amplification of the detection signal.All electrochemical experiments were performed in the working electrode region of the lab-on-paper device.The catalytic material catalyzes the oxidation process of the substrate glucose,thereby obtaining an electrochemical signal.The paper-based electrochemical sensor prepared in this work has high sensitivity and simple operation,and can be successfully used for microRNA detection in serum samples of cancer patients.?2?Research on a novel dual-mode cytosensor based on polyhedral AuPd alloy nanoparticles?PH-AuPd NPs?and three-dimentional reduced graphene oxide?3D-rGO?was constructed for highly sensitive detection of MCF-7 cells.The 3D-rGO was in situ synthesized on the paper working electrode?PWE?by a pollution-free hydrothermal method,increasing the specific surface area and further facilitating the modification of Au nanoparticles?AuNPs?.On the modified electrode,MCF-7 cells and PH-AuPd NPs were separately captured by the aptamer.The PH-AuPd NPs could catalyze H₂O₂ to generate·OH,leading to an amplified electrochemical signal.Meanwhile,as the electrolyte solution flowed,the·OH are transferred outward to the colorimetric detection zone,and catalyzed a chromogenic substrate TMB forms a colored product.The electrical signal measurement and colorimetric detection were carried out on a compatibly designed lab-on-paper device?LPD?,realizing a dual-mode signal readout.This dual-mode cell sensor enables highly sensitive detection of cancer cells and it is successfully used for the determination of actual samples.