Preparation, Characterization And Analytical Applications Of Fluorescent Supramolecular Self-Assembled Monolayers

Self-assembled monolayers (SAMs) is the membrane with superior characters, and has been rapidly developed recently. A great attentions have been paid to SAMs as the sensing membrane. We combine SAMs technology with fluorescence analytical method and develop another interface fluorescence analytical method. It was effective in diminishing the sample volume with a view of on-chip analysis and has higher analytical sensitivity than fluorescence analysis in liquid-phase, therefore, has promising prospects in fluorescence analysis and chemical sensor. This thesis includes the main contents as following:(1) Cysteine was first assembled onto the surface of gold wafer, and then, a fluorescent regent 2-(l-naphthyl)aminoacid (NAA) was indirectly assembled onto the cysteine modified gold wafer by electrostatic interaction between NAA and cysteine, then, the fluorescent bilayer membrane NAA/Cys/Au has been fabricated. The fluorescence quenching from gold could be efficiently eliminated and strong fluorescent signals have been detected from the NAA/cys/Au membrane.NAA was designed for selective for Cu²⁺ and therefore the self-assembled bilayer membrane NAA/Cys/Au has good selectivity for Cu²⁺, so it can be applied to the detection of copper ion. The experimental results show that the fluorescence of NAA/Cys/Au was quenched by Cu²⁺, and the quenching was found to obey Stern-Volmer theory with quenching constant K_sv of 1.22×10⁸ L/mol, which is five orders of magnitude higher than that of NAA in solution. The detection limit for Cu²⁺ is 7.87×10^-11 mol/L. This sensor based SAMs for Cu²⁺ is extremely highly sensitive and has regeneration property and stability.(2) Based on the bridge function of Cu²⁺, we prepare other kind of self-assembled multilayer NAA/Cu/Cys/Au. Copper ion was assembled onto DL-cysteine (Cys) membrane that was directly assembled on the gold surface via Au-S bond, and then NAA was assembled onto the Cu/Cys/Au via coordinate function between NAA and Cu²⁺. The experimental results show that NAA/Cu/Cys/Au has pinhole-free properties that block the interfacial electron transfer from redox couple in solution to the substrate. Besides, the electroconductibility of NAA/Cu/Cys/Au was better than NAA/Cys/Au as a result of indrafting Cu²⁺.(3) Just for nanoparticle has characters of minivolume and large specific surface area, the gold colloidal particle can form extremely dispersive nanometer monolayer on the surface of silylanized glass, cysteine and fluorescent reagent were then assembled to the nanogoldsurface to form another multilayer. This SAMs was characterized by fluorescent spectra, fluorescent microscope and ultraviolet absorption spectra. The results show that it has fluorescent signal and can be quenching by Cu2+, therefore, it has an extremely highly sensitive detection of Cu2+.(4) Diphenylthiourea and it's derivants were assembled onto the gold electrode surface by Au-S bond to form a series of self-assembled monolayer that can supply an orderly microstructure for studying interface electron transfer and anion recognition. The electrochemical characters have been studied by cyclic voltammetry and differential pulse voltammetry. This SAMs electrodes' response to the Ac" and other anion and electron transfer process on interface of the self-assembled monolayer were discussed, and the results showed that the SAMs electrode has potential in anion electrochemical recognition.