荧光性自组装双层膜的制备及其性能研究

Preparation and Properties of Fluorescent Self-assembled Bilayer Membrane

借助Au—S化学键的作用,在金基底上组装DL-半胱氨酸,利用DL-半胱氨酸与1-萘胺乙酸(NAA)的静电吸引作用在金表面间接组装荧光试剂NAA,从而构建了双层自组装膜NAA/Cys/Au.该自组装膜有较强的荧光信号,能被Cu2+猝灭,并具有较好的可逆再生性能,可用于超痕量铜离子的界面荧光测定,对Cu2+的检出下限为7.87×10-11mol/L.同时采用电化学、荧光光谱及电子能谱等方法表征自组装膜的结构,并采用电化学阻抗谱技术和循环伏安法研究自组装膜在K3[Fe(CN)6]/K4[Fe(CN)6]溶液中的电化学行为研究.结果表明,金表面组装的单层膜具有良好的“针孔”效应,组装上荧光试剂之后形成的无“针孔”缺陷的自组装双层膜对溶液与基底间的界面电子转移有强烈的阻碍作用.

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 Cu^(2+) that was allowed for an extremely highly sensitive detection of Cu^(2+) 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 (K_3\)/K_4\ 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.