Preparation Of Self-assembled Mulitlayer Modified Electrode On The Gold Surfaceand Application In Molecular Recognition

A great attention has been paid to self-assembled monolayers (SAMs), which are well-ordered, stable and easy to preparae. SAMs modified electrode is the advanced type of the chemically modified electrodes and have attracted considerable interests in electrochemistry and electroanalytical chemistry. It is very important to construct the new functional SAMs and enlarge their application in biology field. This thesis mainly included the contents as following:1)β-Cyclodextrins (β-CD) was assembled onto the gold electrode by the long chain of the dodecanethiol (C₁₂SH) that was directly assembled on the gold electrode surface. Based on the action ofβ-CD embeding L-Tryptophan the electrochemical impedance ofβ-CD/C₁₂SH/Au SAMs changed. Soβ-CD/C₁₂SH/Au SAMs could recognise the different charge of L-Tryptophan.2) With the help of chemical bonding of Au-S, L-Cysteine (L-Cys) was assembled onto the gold surface to form L-Cys/Au SAMs. Taking advantage of coordinate action of Cu²⁺ with L-Cysteine, the Cu²⁺/L-Cys/Au SAMs were constructed. When Cu²⁺/L-Cys/Au SAMs acted on L-Tryptophan, the electrochemical impedance changed. Cu²⁺/L-Cys/Au SAMs could selectively recognise L-Tryptophan. A novel L-Tryptophan sensor based on electro- chemical impedance with free-labelling was built up.3) With layer-by-layer assembling technology of SAMs, another kind of multi-layers CuHCF/L-Cys/Au was prepared based on the bridge function of Cu²⁺. Compared to the modified electrodes made by other methods, CuHCF/L-Cys/Au SAMs was simple, small disturbance, stable, and had electrocatalysis action to hydroquinone. In 0.1mol/L KCl solution, hydroquinone was determined by the chronoamperometry. The oxidation current has good linearity with hydroquinone concentration within the range of 2.0×10^-5～2.4×10^-4mol/L. Hydroquinone in the environment could be detected with this method.4) Methylene blue (Mb) was indirectly assembled onto the gold surface via the electrostatic interaction bond between Methylene blue and L-Cysteine (L-Cys) and the Mb/L-Cys/Au SAMs were formed. This membrane had strong fluorescence and electrochemical sign. Because of the action between Bovine serum albumin (BSA) and Methylene blue, the SAMs'photo-electrical signs changed and BSA could be detected indirectly. A new biosensor was developed based on the SAMs'interface recognition.