Study On The Electroche Milum Inescence Detection Of Amino Acids

Electrochemiluminescence （ECL） is a chemiluminescence generated by anelectrochemical method. Electrochemiluminescence is a useful analytical tool with thecharacteristics of high sensitivity, good controllability and simple equipment etc. Molecularimprinting technology （MIT） is a molecular recognition technology that has been extensivelystudied in recent years. Based on the incorporation of MIT, an ECL-MIP sensor wasdeveloped in this paper to solve the problem of ECL’s poor selectivity and meanwhile retainthe advantage of high sensitivity of the ECL detections. The sesor was applied to thedetermination of amino acids in this context. So far, looking for the luminescence materialswith higher luminous efficiency is an important research direction in the ECL field. The ECLproperties of an iridium complex （pq）2Ir（acac） were studied in the presence of L-proline as thecoreactant. The main results are shown as follows:（1） An ECL electrode was fabricated with Ru（bpy）₃²⁺as the luminescent material, Nafionas the adsorbent and the multi-walled carbon nanotubes （MWCNTs） as the modifier. Scanningelectron microscope （SEM） was used to observe the surface appearance of the electrode withthe immobilized Ru（bpy）₃²⁺. The preparation conditions such as the amount of Nafion, theMWCNTs and the dispersion liquid were investigated. The ECL electrode was characterizedby the alternating current （AC） impedance method, cyclic voltammetry and ECL method andthe results show that the electrode exhibits a good electroc hemical and ECL performance.Amino acids were detected by the electrode and the ECL regularities were summarized.（2） An ECL-MIP sensor with high sensitivity and good selectivity was prepared by theelectrodeposition of the sol-gel molecular imprinting membrance onto the electrode with theimmobilized Ru（bpy）₃²⁺, which was fabricated by coating the Nafion/MWCNTs/Ru（bpy）₃²⁺membrance on the glassy carbon electrode. The sensor was characterized by SEM, ECLmethod, cyclic voltammetry and AC impedance method. Under the optimum conditions, alinear response was observed with the concentrations of L-phenylalanine from1.0×10-11mol/L to1.0×10-8mol/L and the detection limit was3.1×10-12mol/L. The sensor displayedexcellent reproducibility and stability. The sensor was successfully applied to thedetermination of L-phenylalanine in human serum samples with the recoveries from98.7%to105.0%and in urine samples with the recoveries from94.8%to110.6%.（3） The electrochemistry and ECL behaviors of （pq）2Ir（acac） were investigated inacetonitrile solution with L-proline as the coreactant. A detection limit as low as1.2×10-10mol/L was achieved based on the3σ of blank signals with a linear range from5.0×10-10mol/L to1.0×10-6mol/L. The reaction mechanism between （pq）2Ir（acac） and L-proline wasdiscussed which lays a foundation for the application of （pq）2Ir（acac） in the detection ofamino acids.