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In this paper, glutathione (GSH)-capped gold nanoparticles (GSH-GNPs) were prepared in water media and used for the colorimetric assay of Ca2+. GSH could quickly bind onto the GNP surfaces through its -SH group and the cross-linking of GSH-capped GNPs could be quickly achieved by chelation by its functional groups (-NH2 and-COOH) upon the addition of Ca2+. Color changes were observed from red to blue (or purple) within minutes with the increased concentration of Ca2+, in response to surface plasmon absorption of dispersed and aggregated nanoparticles. Using this colorimetric sensor, the concentration of Ca2+ was determined with a limit of detection low than 1×10-7 M by the naked eye and could further be monitored by a UV-vis spectrometry easily. The possible mechanism of the aggregated GSH-GNPs was discussed by the addition of ethylene diaminetetraacetate (EDTA) and Ca2+ in different orders.
Measuring Technology and Mechatronics Automation (ICMTMA), 2011 Third International Conference on (Volume:2 )
Date of Conference: 6-7 Jan. 2011