Electrochemiluminescence Detection On Microfluidic Chip

In the chapter one, the principle of microfluidic chip was introduced briefly. Then the detection methods of microfluidic chip including laser induced fluorescence, chemiluminescence, electrochemical detection and mass spectrometry were reviewed in detail. Finally, the four main methods of Langmuir-Blodgett method, self-assembly method, polymer mothod and sol-gel method for immobilizing Ru(bpy)₃²⁺ onto the electrode surface were summarized.In the chapter two, a kind of microfluidic chip electrochemiluminescent detection system(microfluidic chip-ECL) using glass chip was made. Ru(bpy)₃²⁺ as luminous reagent, the self-assemble carbon fiber microdisk bundle electrode (CFMBE) as working electrode, the optimum conditions of separation and detection of tripropylamine(TPA) was studied on the system, the conditions were pH 7.6 3.00×10⁽-2 mol·L^-1 for phosphate buffer solution, 1.3 kV for the separation voltage, 1.2 V(vs. Ag/AgCl) for the detection potential, 1.0×10⁽-3 mol·L^-1 for the concentration of Ru(bpy)₃²⁺, 1.0 kV and 10 s for the injection voltage and the injection time. The response for a series of seven injections of 1.0×10⁽-3 mol·L^-1TPA resulted in a relative standard deviation of 2.6% for the ECL intensity and 0.67% for the migration time, respectively.In the chapter three, a kind of electrochemiluminescence micro-electrode was developed, which was immobilized Ru(bpy)₃²⁺ in carbon nanotubes(CNT)/Nafion composite film onto the ITO electrode surface. Tripropylamine(TPA) was determined with the modified electrode. the concentration limit of detection is 2.6×10⁽-9 mol·L^-1 (S/N=3) and the linear range is 1.00×10⁽-8-5.00×10⁽-6 mol·L^-1 with a correlation coefficient of 0.9986. The response for seven continuous cycles scan of 1.00×10⁽-7 mol·L^-1 TPA resulted in a relative standard deviation of 2.3% for the ECL intensity. The micro-electrode performed good ECL signal, good reproducibility and rapid response time. The area of carbon nanotubes(CNT)/Nafion composite film was small in concide with the size of microfluidic chip, but CNT/Nafion composite films were easily fall off from the ITO electrode surface in process of the experiment.So this kind of modified electrode could not be applied in microfluidic chip electrochemiluminescent detection.In the chapter four, a noval electrochemiluminescence micro-electrode of Ru(bpy)₃²⁺-ester immobilized onto the sulfhydryl-derivated indium tin oxide(ITO) electrode surface with AuNPs/Cys composite films was employed. The ECL emission from AuNPs/Cys/ Ru(bpy)₃²⁺-ester composite film of TPA was investigated with TPA as a coreactant. The concentration limit of TPA is 3.5×10^-9 mol·L^-1(S/N=3) and the linear range is 1.00×10^-8-1.00×10^-5 mol·L^-1 with a correlation coefficient of 0.9934. The response for seven continuous cycles scan of 1.00×10⁽-80 mol·L^-1 TPA resulted in a relative standard deviation of 1.9% for the ECL intensity, AuNPs/Cys composite films were not fall off from the ITO electrode surface in process of the experiment, so the modified electrode had good stability. The area of AuNPs/Cys composite films on ITO electrode was coincide with the size of microfluidic chip, so the AuNPs/Cys/ Ru(bpy)₃²⁺-ester modified ITO electrode could be applied on microfluidic chip electrochemiluminescent detection.In the chapter five, the self-assemble microfluidic chip electrochemiluminescence detection system (microfluidic chip-ECL) was employed for the analysis of glutathione(GSH) in single leukemic cell with a carbon fiber microdisk bundle electrode(CFMBE). The optimum conditions of separation and detection were 5.00×10^-3 mol·L^-1 for the concentration of tris(2,2′-bipyridine) ruthenium(II)(Ru(bpy)₃²⁺), 2.00×10^-2 mol·L^-1 phosphate buffer(pH 7.4) for the buffer solution, 1.3 kV for the separation voltage, 1.0 kV and 15 s for the injection voltage and the injection time, and 1.4 V (vs. Ag/AgCl) for the detection potential. The limit of detection is 1.7×10^-7 mol·L^-1 (S/N=3) and the linear range is 5.00×10^-7-1.00×10⁽-5 mol·L^-1 with a correlation coefficient of 0.9976. The response for a series of seven injections of 5.00×10⁽-7 mol·L^-1 GSH resulted in a relative standard deviation of 0.85% for the migration time, and 2.8% for the ECL intensity, respectively. A single leukemic cell in the running buffer was introduced to the double-T crossing by the electrokinetic flow, and then the cell was lysed rapidly under the high electric field of 1.0 kV. GSH in the single leukemic cell was electrically migrated to the detection end of separation channel and was detected on the CFMBE. The amount of GSH in the single leukemic cell was detected to be 0.158^-1.32 fmol.