Study On Construction Of Photoelectrochemical Adaptor Sensor Based On Nanocomposites For Antibiotic Detection

The photoelectrochemistry?PEC?technology is:under visible light,The conduction band electrons then move to the electrode or solution,valence band generates holes,holes are trapped by electron donors,An electrochemical loop is formed between photoelectric materials to generate an electrical signal,When the photosensitive material acts directly or indirectly with the substance to be tested,the electrical signal changes,According to this change,the substance to be tested is analyzed and detected.PEC biosensor has the advantages of low background signal and high sensitivity,which has attracted the attention of researchers.PEC biosensors have been applied in many fields,such as medical monitoring,environmental detection,food inspection,etc.Photosensitive materials are the key to the change of electrical signals generated by PEC biosensor in biological analysis.In this paper,two-dimensional nanomaterials,quantum dots and other commonly used semiconductor materials are used to design PEC aptamer sensors.The detection of antibiotics is realized.The main work is as follows:1.A photoelectrochemical aptamer sensor was constructed based on titanium dioxide nanotubes?TiO₂NTs?,carbon dots?CQDs?and cobalt hydroxide?Co?OH?2?with two-dimensional lamellar structure.Carbon dots have good biocompatibility and non-toxicity,and are matched with the energy levels of titanium dioxide nanotubes,which can promote electron transfer in nanotubes and enhance photoelectric signals.Co?OH?₂ has good PEC properties,and different morphologies are synthesized by different synthesis methods.?-Co?OH?₂ nanosheets are modified on the electrode by electrodeposition and uniformly modified on the surface of the electrode,showing a porous flower-like structure.Therefore,it has a larger specific surface area,thus increasing the connection between the electrode and electrolyte,accelerating the electron transfer rate of CQDs/TiO₂ NTs,and enhancing the PEC performance of CQDs/TiO₂ NTs.The aptamer is then introduce into that sensor forming the PEC aptamer.The sensor has better PEC performance,simple operation process and strong selectivity to SMZ.The PEC aptamer sensor has good stability,reproducibility,simple operation process and strong anti-interference capability.The PEC aptamer sensor has a wide detection range and a low detection limit and can detect SMZ in food and water samples.2.With indium tin oxide glass electrode?ITO?as electrode material,WS₂ and carbon dots?CQDs?with two-dimensional structure are formed into a composite by a simple method and modified on ITO by electrophoretic deposition.Furthermore,The organic material thionine?Th?was modified on the electrode by electropolymerization.CQDs and Th can enhance the absorption of visible light by WS₂,inhibit the compounding of WS₂ electron-cavity pairs,improve its electron conduction rate,and enhance its optical current signal.Firstly,ampicillin aptamer and aptamer complementary strand are formed into a double-stranded structure?ds DNA?,and then the double-stranded structure?ds DNA?is connected to the surface of the electrode through an Au-S bond fixation mode.When ampicillin?AMP?is present,the double-stranded structure is specifically combined with the aptamer?p DNA?in the ds DNA,causing p DNA to fall off from the surface of the electrode,and nucleic acid exonuclease I?Exo I?is introduced,and the Exo I shears the fallen p DNA to release the AMP falling off the p DNA.The released AMP can interact with ds DNA again to realize the recycling of samples.The PEC aptamer sensor has better stability,selectivity,reproducibility and reproducibility.The PEC aptamer sensor has a wider linear range and a lower detection limit when detecting AMP.