A recyclable fluorescence sensor for Hg2+ and Zn2+, based on rhodamine 6G(R6G) and 8-aminoquinoline(8-AQ) co-modified core/shell Fe3O4@Si O2 nanoparticles(denoted as R6G/8-AQ co-functionalized Fe3O4@Si O2 NPs), was developed. R6 G derivative and 8-AQ derivative were conjugated onto the water-soluble core/shell Fe3O4@Si O2 nanoparticles(NPs) by covalent interaction. The R6G/8-AQ co-functionalized core/shell Fe3O4@Si O2 NPs showed fluorescence emission bands at 548 and 480 nm. When the R6G/8-AQ co-functionalized core/shell Fe3O4@Si O2 NPs were coordinated with Hg2+ and Zn2+, emission intensity at 548 nm increased with [Hg2+], while that at 480 nm increased with [Zn2+]. Moreover, there existed approximate linear relationships between fluorescence intensities and concentration of metal ions, in the range of 4.0×10-9–7.65×10-8 M for Hg2+ and 3.3×10-9–3.96×10-8 M for Zn2+, respectively. The lower detection limits for Hg2+ and Zn2+ were 1.0×10-9 and 3.0×10-9 M, respectively. The R6G/8-AQ co-functionalized core/shell Fe3O4@Si O2 NPs showed good selectivity to Hg2+ and Zn2+ over other common metal ions examined in neutral aqueous solutions. Moreover, the R6G/8-AQ co-functionalized core/shell Fe3O4@Si O2 NPs could be recycled from the detected samples using a magnet. This work has thus showed not only a practical sensing method for Zn2+ and Hg2+, but also a promising guide to the design of fluorimetric/colorimetric sensors for other targets.
We report a simple approach for the fabrication of cheap but effective surface-enhanced Raman scattering(SERS) active substrates consisting of natural egg shell membrane(ESM) grafted with Ag-nanoparticles(Ag-NPs) decorated carbon nanotubes(CNTs)(denoted as Ag-NPs@CNTs@ESM),via ultrasonic adsorption of CNTs on the ESM and the subsequent Ag-sputtering.As high density Ag-NPs were sputtered onto each CNT anchored on the ESM nanofiber,homogeneous nanoscaled gaps between the neighboring Ag-NPs were achieved,leading to high SERS activity with excellent SERS signal homogeneity over the whole membrane.Using the Ag-NPs@CNTs@ESM membranes as SERS-substrates,methyl parathion(one of the most hazardous insecticides),PCB-3(one congener of polychlorinated biphenyls belonging to persistent organic pollutants) and bovine serum albumin(BSA,biomolecules) with a concentration down to 10-11 M,10-6 M and 0.1 ppb were detected respectively,showing promising potentials in rapid trace detection of environmental pollutants and biochemicals.
