Fabrication And Application Of Electrochemiluminescence Sensors Based On One-dimensional Carbon Nanotubes And Two-dimensional Layer Nanocomposites

In recent years,electrochemiluminescence?ECL?sensors have been paid close attention owing to its low background signal,rapid response,high sensitivity,wide dynamic range versatility and easy operation.Thus,they are widely applied in many important analytical fields,such as immunoassay and environmental,food and drug analysis and molecular diagnosis of disease and so on.Some nanocomposites have excellent properties such as large specific surface area,chemical reactivity and size effect.The application of nanocomposites as immobilized materials in the construction of ECL sensors can significantly improve their performance.In this paper,multiwalled carbon nanotubes/gold nanocomposites?MWCNTs-Au?,layer MnO₂-Ag nanocomposites?MnO₂/Ag@BSA?and Ag-C₃N₄ were applied for the fabrication of ECL sensors.At the same time,there was a comparison with previous studies,the proposed ECL sensors owned a relatively wider linear range and lower detection limit.The major contents in this thesis are described as follows:?1?An electrochemiluminescence?ECL?sensor for bisphenol A was proposed by using L-cysteine-functionalized multiwalled carbon nanotubes/gold nanocomposites-modified glassy carbon electrode?MWCNTs-Au/GCE?based on ECL of peroxydisulfate solution.The ECL behaviors of peroxydisulfate solution had been investigated at the chitosan/MWCNTs-Au/GCE,and bisphenol A was found to have quenching effects on the ECL of peroxydisulfate solution.Both Au nanoparticles?AuNPs?and multiwalled carbon nanotubes could promote the electron transfer and synergetically amplify the ECL signal of peroxydisulfate solution.Under the optimized conditions,the ECL signal intensity was linear with the concentration of bisphenol A in the concentration range between 0.25 and 100 ?M?R = 0.9931?with a detection limit?S/N=3?of 0.083 ?M.The constructed ECL sensor has the advantages of simplicity,sensitivity,good selectivity and reproducibility,exhibiting a great potential application in determination of bisphenol A.?2?A novel ECL biosensor was proposed for determination of cholesterol by utilizing MnO₂/Ag@BSA as a neotype matrix for the fabrication of sensing platform.This work combined enzymatic catalysis to in situ produce coreactant as an efficient strategy to stabilize and enhance the ECL emission.The enzymatic reaction of cholesterol oxidase?ChOx?and cholesterol can generate H2O2 in situ,which is a feasible method to promote the ECL of luminol through the formation of luminol-H2O2.The fabrication process,analytical performance,specificity,ECL detection and electrochemistry of the ECL biosensor were studied in detail.A good linear relationship between the ECL intensity and the concentration of cholesterol was obtained from 0.21 to 1667 ?M with a limit of detection?LOD?of 0.07 ?M?signal-to-noise ratio of 3?.Moreover,the sensitive and cost-effective as-proposed cholesterol biosensor exhibits good sensing performance with high specificity,long-term stability and good reproducibility.Furthermore,this approach can detect cholesterol in human serum samples with acceptable recoveries,suggesting its promising application under physiological conditions.?3?A novel electrochemiluminescence sensor based on Ag-C₃N₄ and persulphate light emitting system was constructed.The glassy carbon electrode?GCE?was modified with carbon nitride materials and chitosan.In the presence of the luminescent substance?S2O82-?,the sensor exhibited excellent performance and could be used for the actual detection of dopamine in serum.Under the optimal conditions,the prepared ECL sensor presented a response to dopamine with a linear range from 0.015 to 150 ?M.The detection limit?LOD?of the sensor was 0.005 ?M.The constructed ECL sensor has wide linear range and good stability,this method is simple,non-toxic,time-saving,low cost compared with other detection methods,which can also provide ideas for the detection of other substances.