| The toxic Hg2+ has caused serious pollution to the environment and extremely hazards to the health of people, therefore many researchers are committed to develop rapid and simplified methods for detecting Hg2+ with high sensitivity, selectivity and less samples required. In this paper, we prepared several fluorescence chemosensors for detection of Hg2+ in aqueous media based on the principle of metal-enhanced fluorescence effect.Firstly, the metal mesoporous material Ag-HMS-s was synthesized by an in situ-one pot method. A high sensitivity and selectivity fluorescence chemosensor for detecting Hg2+ in aqueous media with dual fluorescence and colorimetric signals was prepared by functionalizing Ag-HMS-s with probe R. This chemosensor presents fast response, high sensitivity and selectivity for Hg2+ in aqueous media. The response of s-HMS-Ag-R for Hg2+ was monitored by fluorescence and ultraviolet-visible absorption spectra. The fluorescence intensity of s-HMS-Ag-R showed a good linear relationship with low concentration of Hg2+ The detection limit of the chemosensor is 0.7 ppb. The color of s-HMS-Ag-R suspension changed from colorless to pink and deepened gradually with increasing Hg2+, which could be detected by the naked eye immediately. More importantly, the chemosensor could be regenerated by simple chemical treatment with TPAOH and reused.The metal mesoporous material Ag-HMS-r and Au-HMS-r were synthesized by a simple impregnation-reduction method. Then chemosensors r-HMS-Ag-R and r-HMS-Au-R were assembled by functionalizing the metal mesoporous materials with probe R. The metal enhanced fluorescence effect with Ag and Au nanoparticles were studied using fluorescence enhancement factors. The optimal metal content in both metal mesoporous materials were 2 wt%. The metal enhanced fluorescence effect of Ag NPs is stronger than that of Au NPs. The enhancement factors of Ag and Au NPs for R were 4.7 and 3.3, respectively. The principle of metal enhanced fluorescence effect of Ag and Au NPs was also verified by local surface plasmon resonance spectroscopy and fluorescence decay lifetime. The excited state energy of probe R was reduced due to the energy transfer from the probe R to Ag or Au NPs. At the same time, the Ag and Au nanoparticles increase the radiation attenuation rate and fluorescence quantum yield of probe R. So Ag and Au NPs have metal enhanced fluorescence effect for R.In order to improve the selectivity of chemosensors for Hg2+, we synthesized a new fluorescent probe R-2SH by modifying probe R with sulphydryl considering the thiophilic nature of mercury. The complexation constant of R-2SH-Hg2+ is five times as that of R-Hg2+. A new chemosensor r-HMS-Ag-R-2SH with high selectivity was prepared by functionalizing Ag-HMS-r with this new fluorescent probe R-2SH. The response of r-HMS-Ag-R-2SH for Hg2+ was monitored by fluorescence and ultraviolet-visible absorption spectra. r-HMS-Ag-R-2SH has well signal response for Hg2+ in water-methanol (9:1) media. The anti-interference ability of r-HMS-Ag-R-2SH was obviously improved, especially for trivalent metal ions (Al3+, Cr3+, Fe3+). r-HMS-Ag-R-2SH also presents well signal response for Hg2+ in rain water and can be used to recognize Hg2+ with naked eye. More importantly, r-HMS-Ag-R-2SH could be regenerated by simple chemical treatment with Na2S. 属性不符 属性不符... |
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