Phytic acid (IP6) and its salts are promising reagents to alleviate corrosion of metals, which are environmentally friendly and highly efficient, compared to some traditional inhibitors toxic to environment. This paper reports the studies of the structure and anticorrosion features of two kinds of the self-assembled monolayers (SAMs) of IP6 at the silver surface under various pH values, 1.27 and 13, by using electrochemical and surface enhanced Raman scattering (SERS) spectroelectrochemical measurements. On the basis of recorded ex situ SERS spectra, different adsorption modes of both resulted SAMs of IP6 at the silver surfaces have been postulated. In addition, based on in situ SERS electrochemical measurements, a tentative explanation for the difference in corrosion potentials of two kinds of the silver surfaces in the presence of SAMs formed from completely protonated or deprotonated IP6 molecules has also been presented.

The self-assembled monolayers (SAMs) of 6-mercaptopurine (6MP) were formed at the roughened polycrystalline gold surfaces in acid and alkaline media. The time-dependent Raman mapping spectral analysis in conjunction with the quantum calculations for the vibrational modes using ab initio BLYP/6-31G method suggested that both of the resulted 6MP SAMs adopted the same adsorption mode through the S atom of pyrimidine moiety and the N7 atom of the imidazole moiety anchoring the gold surface in a vertical way. The in situ surface-enhanced Raman scattering spectroelectrochemical experiment was conducted to examine the stability of the SAMs at various bias potentials. It was found that the detaching process of the 6MP SAMs from the surface involved one electron reduction as the voltage was applied at ca. 0.7 V vs a standard calomel electrode.

Abstract:A planar amperometric glucose microsensor based on glucose oxidase immobilized by chitosan film on Prussian Blue layer has been developed. The experimental results show that the optimum detection potential is 50 mV (versus Ag/AgCl) and the optimum pH is 6.5. Under the selective conditions the sensor exhibits excellent sensitivity of 98 nA/M and a linear range of 0.1-6.0 mM. The apparent Michanelis-Menten constant of the sensor is 21 mM. The response time is less than 60 seconds. No apparent change in the response to glucose was observed during one month. Foremost, the interference of ascorbic and uric acids can be avoided due to selective permeability of chitosan film and electrocatalysis of PB layer to H 2 O 2 . The sensor has been applied to detect glucose in human blood serum.

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