Studies On Preparation Characterization Application Of Mercaptan Self-assembled Monolayers

Self-assembled mono layers (SAMs) is spontaneous assembled to form a kind of an orderly, thermodynamic stability of single layer (or more) membrane by the interaction of molecular and basal material. It has some properties of uniform, high density and low defects. And we can accord to the preliminary design of molecular structure and electrode surface, through the precise chemical control, and obtain the desired interface of excellent physical and chemical properties. Self-assembled monolayers technology as a simple and convenient method of forming membrane have broad prospect of application in the electrochemical catalysis and analytical method, biosensor and molecular devices.Among various kinds of SAMs system, thiol compounds that bind on the gold electrode surface by polar covalent bond to form SAMs become the most widely studied SAMs system due to its simple preparation, stability and high degree of order.This paper is centered on SAMs technique and used several thiol compounds to prepare stability SAMs. Use electrochemical and non-electrochemical method to character SAMs, at the same time, examine surface properties of the different chain length and the different end groups of thiolation self-assembled membrane, and the detection of glucose electrochemical behavior had on study. The paper mainly includes the following aspects:1. Based on theoretical analysis of SAMs, the paper had respectively prepared five kinds of the thiol SAMs. These SAMs are1-UndecanethioI SAMs,10-mercapto-1-decanol SAMs,6-mercaptohexanoic acid SAMs,16-mercaptohexadecanoic acid SAMs,11-mercaptoundecanoic acid SAMs. The functionalized effect was characterized by SEM and Raman spectroscopy. It shows that thiol molecules had been steadily binded on the gold electrode surface. 2. This paper has analysed the electrochemical behavior of five kinds of thiol self-assembled monolayers by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Because the thiol SAM electron transport rate is slow, redox peaks of cyclic voltammograms decreased significantly. Electron transfer resistance of SAMs increased than bare gold electrode. It showed that the gold surface was covered by SAMs, the SAMs blocked [Fe(CN)6]3-/4-probe ion electron transfer, and it proved that the electrode modification effect is good.3. Finally, the electrochemical behavior of five thiol SAMs detecting glucose was analyzed by CV and EIS. When end groups of SAMs are same, with the carbon chain length increases, oxidation peak current of detection glucose CV gradually decreases. Correspondingly, electron transfer resistances of SAMs surface are on the rise. When carbon chain lengths of SAMs are same, these SAMs end groups respectively are-COOH、-OH and-CH3, it verified that-COOH SAMs showed sensitivity for glucose detection.