科研之友
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摘要
The glyco-conjugate, L-S, its Hg2+ complex, and the L-O were synthesized and characterized in their solid state by FTIR, diffuse reflectance, and powder XRD. The mercury complex shows dumbbell-like microstructures as a result of the metal ion-induced aggregation of the glyco-conjugate as studied based on scanning electron microscopy. The aggregation was also supported by atomic force microscopy. The Hg2+ was detected on L-S-coated silica gel sheets by switch-on fluorescence, wherein, the enhancement in the fluorescence intensity varies linearly with the added Hg2+ in the concentration range 5-60 mu M. The concentration-dependent variation was also detected on silica gel sheets by viewing their colour under 365 nm light. Hg2+ was detected by the L-S-coated silica gel sheets by switchon fluorescence even in the presence of blood serum. Thus, this method is extendable for the detection and quantification of Hg2+ present in blood and or in biological fluids using disposable silica gel sheets. The sensing of Hg2+ in HEPES buffer solution is well demonstrated in this paper using various techniques, such as fluorescence, absorption, visual color, ESI MS, and H-1 NMR. In the buffer medium, the L-S exhibit selective chromogenic as well as fluorogenic properties towards Hg2+ by showing similar to 75-fold higher fluorescence emission intensity and the studies were further extended to show that none of the 13 ions studied compete for Hg2+. A minimum detection limit of 25 +/- 4 ppb was shown by L-S for Hg2+ in the buffer. All the experimental studies carried out support the formation of 2 : 1 complex between L-S and Hg2+. At higher mole ratios of Hg2+, the same yields the oxo-product, viz., L-O. The structure of the 2 : 1 complex was modeled by DFT using B3LYP/LANL2DZ.
- 出版日期2014
