Recyclable fluorimetric and colorimetric mercury-specific sensor using porphyrin-functionalized Au@SiO2 core/shell nanoparticles

Abstract

A fluorimetric/colorimetric mercury sensor based on Au@SiO(2) core/shell nanoparticles has been developed and demonstrated. The porphyrin derivative (2) was attached to Au@SiO(2) core/shell nanoparticles by covalent bonds and showed a red color and strong fluorescent properties. In the absence of specific metal ions, the porphyrin-functionalized Au@SiO(2) nanoparticles (1) exhibited strong fluorescence emission and were red in color. The addition of Hg(2+) ion to 1 resulted in a color change from red to green within 10 s and a weak display of fluorescence. Conversely, no significant changes in fluorescence emission or color were observed in the parallel experiments with Li(+), Na(+), Ca(2+), Cu(2+), Cd(2+), Co(2+), Mn(2+), Cd(2+), Ag(+) and Pb(2+). Regarding the reversibility of 1, the fluorescence and color of 1 in the presence of Hg(2+) ion were found to be almost reversible when 1 was treated with EDTA solution. Furthermore, a study of the effect of pH on 1 with bound Hg(2+) ion indicated that the fluorescence intensity and color change of 1 was almost constant between pH 4 and 10. This sensor has excellent selectivity and sensitivity over other metal ions and has detection limits below the maximum contamination level of 1.2 ppb for Hg(2+) ion in drinking water, as defined by the U. S. Environmental Protection Agency (EPA). The results obtained not only allow a practical sensing application for the Hg(2+) ion but also serve as a guide for the design of fluorimetric/colorimetric sensors for other targets.

Colorimetric detection of mercury ion based on unmodified gold nanoparticles and target-triggered hybridization chain reaction amplification

“…Therefore, sensitive and selective mercury detection is very important for environment monitoring and food analysis. Up to now, several conventional methods have been developed, such as cold vapor atomic fluorescence spectrometry [3], inductively coupled plasma mass spectrometry [4,5], surface enhanced Raman scattering [1,6], electrochemical methods [7,8], fluorescent methods [9][10][11] and colorimetric methods [12][13][14][15][16][17][18][19][20][21]. Among these methods, gold nanoparticles (AuNPs)-based colorimetric assay has drawn great attention [12][13][14][15][16][17][18][19][20][21][22][23], since it is a simple, fast and efficient method for determining targets with the aid of obvious color change.…”

Fluorescence enhancement of europium complexes by core–shell Ag@SiO2 nanoparticles

“…In order to study the effect of distance between lanthanide complexes and metal nanoparticles on the metal-enhanced fluorescence, we develop core-shell Ag@SiO 2 nanoparticles with various shell thickness of around 10, 15 and 25 nm [19][20][21][22]. Results demonstrate that the introduction of Ag@SiO 2 nanoparticles into the europium complexes' solution can significantly enhance the fluorescence intensity of the complexes and the fluorescence enhancement is the strongest when the shell thickness of Ag@SiO 2 nanoparticle is 25 nm.…”

Trace colorimetric detection of Pb 2+ using plasmonic gold nanoparticles and silica–gold nanocomposites

“…Therefore, the rapid, sensitive and trace level detection of Pb 2+ ions is of great importance in public interest. While many effective fluorescent sensors have been successfully developed for various metal ions [15][16][17][18][19], there have been relatively few reports on Pb 2+ ions sensing via selective fluorescent sensors [20][21][22][23][24].…”

“…Triazocarboxyl AgNPs show a cooperative effect on the recognition of Co 2+ over other metal ions tested [35] while mercapto pyridine glutathione-modified AuNPs was used as a colorimetric sensor for As 3+ in groundwater [36]. Moreover, the metal NPs show excellent selectivity and sensitivity as colorimetric sensors when these are mostly of spherical morphology [3,11,12,19,35,36]. Simple, cost-effective and rapid colorimetric method for simultaneous detection of Hg 2+ , Pb 2+ and Cu 2+ using papain enzyme-functionalized AuNPs has been developed with detection limit 200 nM [37].…”