| Electrochemiluminescence-based biomarker detection has been developed rapidly over the years.However,most of the research depends on step-by-step chemical modification of the electrode surface to immobilize recognition units.This detection method not only makes it difficult to reproduce the surface state of the electrode,but also costs a lot of time in the preparation process of the electrode,which makes it difficult to realize mass production and automated detection.In addition,most of the current research has focused on the principle assay of the sandwich-type labeling method,which often requires the addition of a luminescent probe-labeled secondary antibody for incubation,which prolongs the preparation time of the assay.Therefore,it is imperative to develop a sensing platform that can be built quickly.Hot electroninduced cathodic electrochemiluminescence(HECL),as an important branch of electrochemiluminescence,has been relatively slow in research and development over the years owing to its high demand for electrode insulation and power sources.However,since HECL is contrary to the need for good conductors in conventional electrochemiluminescence,researchers can use poor conductors as carriers for electrochemiluminescence,which has raised concerns.This dissertation concentrates on the two points of electrochemiluminescence research development needs.In the field of conventional ECL,with magnetic luminescent materials as the carrier,we fabricated a label-free sensing platform based on a three-electrode electrochemical system.In the field of HECL,we developed two new insulating electrodes and completed the mechanistic study of the method and the development of the sensing platform.In addition,we have regulated our self-developed instrument to meet the needs of detection.The specific results achieved are as follows:1.We constructed a bifunctional electrochemiluminescent probe based on magnetic nanoparticles and realized a label-free method to determine cardiac troponin I.First,we synthesized spherical magnetic nanoparticles by a solvothermal method and coated them with a shell structure of silica.At the same time,Ru(bpy)32+was embedded in a three-dimensional structure of silica,resulting in a magnetic and luminescent dualfunction nanomaterial.Based on the property that the silica shell layer can be easily modified with various functional groups by the action of silylation reagents,we modified the silica shell layer with amine groups by 3-Aminopropyltrimethoxysilane(APTMS)and successfully modified the antibody to cardiac troponin I by glutaraldehyde.Combined with our self-designed flow detection device,the fabricated sensing platform can be built quickly in less than 15 minutes.After the actual blood sample verification,the material has good selectivity for cardiac troponin I,and its detection limit can reach 15 pg mL-1,showing potential application prospects.2.We used dimethyl silicone oil as an insulating layer on the surface of the glassy carbon electrode,which hindered the electron transfer process of conventional electrochemistry,induced electrons to tunnel through the insulating coating and maintain their own high energy to form hot electrons.In the presence of water molecules,the hot electrons formed strongly reducing hydrated electrons,which coexisted with the strongly oxidizing sulfate radicals generated by the added peroxodisulfate,inducing a rapid oxidation and reduction process of Ru(bpy)32+.In this experiment,the mechanism of HECL was verified with hydrated electron quencher and ECL spectra,and the efficiency of hot electron injection was tuned to obtain stable electrode interface and HECL signal.We finally achieved a detection limit of 6.3 μmol L-1 with geranylin as the detection target.The fabrication process of this insulating electrode is simple and fast,which can be well applied in HECL and is expected to be further extended to the construction of novel functional group-modified insulating electrodes.3.Based on the self-assembly process of thiols on gold electrodes,a thicknesscontrollable insulating electrode was constructed for the study of HECL.By controlling the chain length of thiol molecules to control the film thickness,we constructed straight-chain alkyl thiol modified electrodes with different numbers of methylene groups and investigated the effect of film thickness on the tunneling process of hot electrons.In addition,as the number of methylene groups of thiol molecules rose,the self-assembled film layers exhibited highly insulating properties,which further limited the electron transfer process only through the tunneling path.We finally found that the self-assembled film formed by n-cetylthiol was most suitable for the HECL reaction,and the characterization results in various ways showed a thickness of 2.6 nm.In addition,based on the stability protection of thiol self-assembled electrodes during hot electron injection,we developed our own supporting power generation device and optimized the optimal pulse conditions,and finally realized the detection of dopamine with a linear range from 1 nmol L-1 to 10 μmol L-1 and a detection limit of 0.3 nmol L1.The development and utilization of self-assembled electrodes in the field of HECL benefits researchers to realize further modification of insulated electrodes,which lays the foundation for us to realize the capture detection of biomarkers in the future. |
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