Abstract: Fluorescent reagent 2-(1-naphthyl)aminoacetic acid(NAA) was assembled onto the gold surface via its electrostatic interaction with DL-cysteine(Cys) that was directly assembled on the gold surface via Au_S bond. Strong fluorescence was observed from the NAA self-assembled bilayer membrane on the gold surface and was highly efficiently quenched by Cu²⁺ that was allowed for an extremely highly sensitive detection of Cu²⁺ with a detection limit of 7.87×10^-11 mol/L. The fluorescence from NAA/Cys/Au can be easily the regenerated and therefore the present report showed a reusable method for immobilizing reagent in fabricating fluorescent chemosensors. The self-assembled monolayer and bilayer were primarily characterized by electrochemical method and electron energy spectrum. The electrochemical behavior of the SAMs on the gold electrode in the solution of (K₃)/K₄ was investigated by cyclic voltammetry and AC impedance spectroscopy. The result of the experiment shows that Cys/Au has an excellent pinhole property to enhance the interfacial electron transfer, when the NAA was assembled onto the electrode the pinhole-free properties block the interfacial electron transfer from redox couple in the solution to the substrate.

Key words: Interfacial fluorescence, Self-assembled bilayer membrane, Cyclic voltammetry, Electrochemical impedance, Copper ion