The Study And Application Of Electrochemiluminescence Sensor Based On CdSeTe/ZnS QDs And CeO₂ Nanomaterials

Electrochemiluminescence,abbreviation for ECL,is an analytical technology,which combines electrochemistry with chemiluminescence effectively.It is the process whereby species generated at electrode surfaces undergo high-energy electron-transfer reactions to form excited and it emited light.ECL has attracted a large number of researchers,because of its simplified optical setup,low background signal,fast analysis,high sensitivity and easy potential controllability.In the past decades,the ECL has developed rapidly,and has been widely used in many fields,including biology,medicine,environment,foodstuff and immunoassay.But the constructed sensor based on the ECL has poor selectivity and anti-interference,which cannot be ignored.Therefore,three kinds of ECL biosensors were constructed by combining the specific selectivity of molecular imprinting technique?MIT?with the high sensitivity of ECL based CdSeTe/ZnS quantum dots?QDs?and CeO₂nanomaterials in this paper.And then,these analysis performances of biosensors were improved because of the magnified ECL intensity based on multi-walled carbon nanotubes,gold nanoparticles,reduction of graphene oxide and cerium oxide nanorod nanomaterials.And the main works could be summarized as follows.1.A novel of eco-friendly molecularly imprinted electrochemiluminescence biosensor was designed,based on nanomaterials,including MWCNTs,AuNPs,CdSeTe/ZnS QDs and molecularly imprinted polymer composites,and it would be applied in the determination of dopamine.In order to improve the analysis performance of the biosensor,it has combined the superior selectivity of MIT with the high sensitivity of ECL.And the cavities in molecularly imprinted polymer after eluting with the ethanol and water mixture were applied as the substrate to capture target molecular dopamine.The electron transform channel for redox reaction of CdSeTe/ZnS QDs and co-reactants K₂S₂O₈ was blocked with the increasing of dopamine concentration,resulting in the ECL intensity decreased correspondingly.Furthermore,the electron transfer might occur between the excited state QDs*and the dopamine or the product of dopamine in the redox reaction,which lead to the quenching effect on the cathodic ECL again.The biosensor showed high sensitivity for dopamine detection with the lowest detection limit of 3.3×10^-15mol/L.And it has been successfully applied to detect the dopamine in the human serum with high selectivity and stability.2.In the chapter,three different morphologies of ceria were synthesis at first,including ceria nanocube,ceria nanorods and ceria nanosphere.The experimental result showed that the ECL intensity of ceria has a close relationship with the oxygen vacancy.After that,four kinds of rod-shaped ceria with different oxygen vacancy density were prepared,and the big oxygen vacancy density would make the specific surface area become large,and the ECL signal become strong correspondingly.Besides,the ECL biosensor was incubated based on CeO₂-NC and the rGO@AuNPs/GCE which was obtained by one-step reduction method.It was found that the electron transfer might occur between tyrosine and ceria by theoretical calculation method.Therefore,the ECL sensor based on ceria nanocube could be used for detection tyrosine with predominant analytical performance.And the cerium oxide nanomaterial with the strong ECL would be applied for detecting others target.3.The MIP-ECL sensor was constructed based on the molecularly imprinted polymer films prepared by electrochemical polymerization with o-PD as the functional monomer and 2,4-D as template molecule,respectively.The ceria nanomaterial with good catalytic performance would promote the production of SO₄^-·from K₂S₂O₈,which could result in the ECL intensity of CdSeTe/ZnS QDs increasing.Comparing with the differential pulse voltammetry sensor,the ECL sensor showed good analytical performance with wide linear and low detection limit for detecting2,4-D.Therefore,cerium oxide nanomaterial is expected to replace the precious metal to improve the sensitivity for the sensor contruction.