R6G/8-AQ co-functionalized Fe3O4@SiO2 nanoparticles for fluorescence detection of trace Hg2+ and Zn2+ in aqueous solution

Abstract

usage of mercury and its compounds in industry and the steadily increased use of fossil fuels. Moreover, bacteria in the natural environment can convert inorganic mercury to neurotoxic methylmercury, which can be bio-accumulated through the food chains [7,8]. Therefore, mercury and its compounds are potential threats to the public health. According to the USA Environmental Protection Agency, the standards for the maximum allowable levels of Zn 2+ and Hg 2+ in drinking water are 7.7×10 -8 M and 1.0×10 -8 M, respectively. Thus developing a sensing method for such low concentrations of Zn 2+ and Hg 2+ in aqueous solution is of great importance.Traditional laboratory techniques for the detection of metal ions include atomic absorption spectrometry [9], inductively coupled plasma-atomic emission spectrometry [10], and inductively coupled plasma-mass spectrometry [11], which are generally costly and time-consuming because of their tedious and complex sample pre-treatments. It is therefore exigent to develop simple, rapid and inexpensive methods for detection of heavy metal ions.Fluorescence sensor has advantages of low cost, simplicity and high sensitivity. Indeed, designing fluorophore-based chemo-sensors for heavy metal ions has gained special attention [12]. Up to now, several fluorescence sensors for Zn 2+ and Hg 2+ have been developed [13][14][15][16]. However, for these fluorescence-based sensors, both external environment and the instrument itself can readily affect the test results. To solve this problem, ratiometric fluorescent sensors have been favourably devised [17][18][19][20][21][22][23][24]. Furthermore, to improve the detection sensitivity, a new trend is to apply nanoparticles (NPs) in sensor designs [25,26]. It has been reported that the solubility of small organic molecules (fluorophores) in water solution can be improved by M, respectively. The R6G/8-AQ co-functionalized core/shell Fe3O4@SiO2 NPs showed good selectivity to Hg 2+ and Zn 2+ over other common metal ions examined in neutral aqueous solutions. Moreover, the R6G/8-AQ co-functionalized core/shell Fe3O4@SiO2 NPs could be recycled from the detected samples using a magnet. This work has thus showed not only a practical sensing method for Zn 2+ and Hg 2+, but also a promising guide to the design of fluorimetric/colorimetric sensors for other targets.

Optical assays based on colloidal inorganic nanoparticles

“…SiO 2 , due to their optical and fluorescent properties, are widely used in rapid diagnostic processes that require high sensitivity [314, 315]. These NPs can be used as coatings for other NPs due to their stability and catalytic properties [316–318]. Ag@SiO 2 core shell NPs were used in a study to detect pyrethroid insecticides (including lambda-cyhalothrin, LC) based on a colorimetric technique [317].…”

Green Synthesis of an Amide-Based Chemosensor and Its Application for Detection of Toxic Metal Ions

“…The type of interaction between chelate and the metal ion is a coordinate bond or host-guest type. 11 Various methods have been used for detection of the metal ions such as rhodamine 6G (R6G) and 8-aminoquinoline (8-AQ) co-modified core/shell Fe3O4@SiO2 nanoparticles used for detection of Hg 2+ and Zn 2+ ions in aqueous solution, 12 Rhodamine B chemosensor used for detection of Pb 2+ in acetonitrile, 13 azadiene-pyrene derivative for Hg 2+ in aqueous acetonitrile solution, 14 (E)-2-(5-((2-carbamothioylhydrazono)methyl)-6-hydroxy-3-oxo-3H-xanthen-9-yl)benzoic acid for the detection of Cd 2+ ions in aqueous solution, 15 N-(1,10-phenanthrolin-5-yl)-2,2diphenylacetamide for selective detection of Fe 3+ in an aqueous medium, 16 8-hydroxyquinoline based graphene oxide for detection of Zn 2+ in aqueous media, 17 cyclometalated platinum(II) bipyridylacetylide complex for Mg 2+ in acetonitrile, 18 rhodamine-based compound for Pd 2+ in pure water, 19 and for highly selective detection of Ag(I) ions. 20 The syntheses of chemosensors are reported in the literature by various methods from readily available starting materials such as water meditated synthesis of CF1-CF3 and use for detection of CN -1 .…”