Construction Of Biosensors Based On Nanocatalytic Materials And Their Applications In Small Molecule Detection

Electrochemical biosensors have great potential in epidemic prevention,medical diagnosis,environment monitoring or food safety due to their fast response,miniaturized size,low cost and easy operation.Electrochemical biosensors analyze small molecules by electrocatalyzing their redox groups specifically.The nanomaterial-based catalysts have many advantages such as having good chemical stability,high conductivity,large specific surface area,and wide distribution of active sites,which can further improve the detection performance of the electrochemical biosensor on small molecules.In this dissertation,two different types of nanomaterials were synthesized for the electrochemical detection of free bilirubin in human serum and formaldehyde in food samples,respectively.1.Combined with the good electrocatalytic activity of ceria nanocubes(ceria NCs)and the high conductivity of carbon black materials(CB),ceria NCs/CB composites were prepared,characterized,and applied on the free bilirubin electrochemical biosensor.Under the optimized conditions,the limit of detection for free bilirubin in buffer solution was 0.1 ?M,and the limit of detection for free bilirubin in real human serum sample was 1.0 ?M.This electrochemical sensor also showed high selectivity and stability.2.A formaldehyde electrochemical biosensor based on Ag-Pt bimetallic core-shell nanostructure/ reduced graphene oxide(r GO)composite was prepared and characterized.By combining the high catalytic activity of pentagram shaped Ag-Pt bimetallic core-shell nanomaterials with the high conductivity of r GO nanosheets,the sensor showed excellent sensitivity on formaldehyde electrocatalytical oxidation.The limit of detection for formaldehyde in buffer solution was 1.0 ?M,and formaldehyde was successfully measured in tap water,orange juice and beer environment.The electrochemical detection system used screen-printed electrode(SPE),only5.0 ?L sample volume was required in the detection process,ensuring the high sensitivity and selectivity of electrochemical biosensor at the same time.Moreover,it is not restricted by the operating location or environment.It has enormous potential in point of care tests and rapid food safety on-site detection.