Preparation of MHS Nanosensor Particles and Their Potential Application for Metal Ion Sensing Device.

초록

Metal ions are one of major concerns in environment and public health and the determination of their concentrations is very important. The metal ion concentrations have been determined by the analytical tools such as absorption spectrometry, electrochemical methods, and fluorescence spectrometry. However, development of simple, inexpensive, and fast responsive sensors for important metal ions is in high demand for on-site monitoring of metal ion concentrations. In our work, we have developed sensors for Zn2+, Cd2+, and Hg2+ based on prepared multi-functional hybrid silica (MHS) particles including vinyl, amine, and thiol functional groups. The sensors were prepared as follows: The MHS particles were prepared by modified sol-gel process; the amine groups of MHS particles were converted to carboxy groups and applied on the amine patterned substrate to form a self-assembled layer of MHS particles; the thiol group of the MHS particles were oxidized to SO3H by addition of H2O2 solution; and then TMPyP (α,β,γ,δ-tetrakis(1-methylpyridinium-4-yl)porphine p-toluenesulfonate) sensor molecule were bound to thus modified MHS particles by ion-pair interaction between negative (SO3H) and positive charge (TMPyP). In the presence of Zn2+, Cd2+, and Hg2+, the visible color of sensor particles is changed from orange to green due to the formation of complex between TMPyP and the metal ions. The complex with each different ion exhibits different absorption peak at nm for Zn2+, nm for Cd2+, and nm for Hg2+, repectively, enabling selective detection of each ion. A discernible color change in MHS sensor particles would be a rapid indication of the existence of heavy metal ions, while the quantitative determination of a metal ion concentration could be obtained from an absorption spectroscopy.