Fabrication of an “ion-imprinting” dual-emission quantum dot nanohybrid for selective fluorescence turn-on and ratiometric detection of cadmium ions

Abstract

In this work, we have fabricated a new dual-emission quantum dot (QD) nanohybrid for fluorescence ratiometric determination of cadmium ions (Cd) in water samples, where the "turn-on" model and "ion-imprinting" technique were incorporated simultaneously. The nanohybrid probe was composed of green-emitting CdSe QDs covalently linked onto the surface of silica nanoparticles embedded with red-emitting CdTe QDs. The chemical etching of ethylene diamine tetraacetic acid (EDTA) at the surface produced specific Cd recognition sites and quenched the green fluorescence of outer CdSe QDs. Upon exposure to different amounts of Cd, the green fluorescence was gradually restored, whereas the inner red fluorescence remained constant. As a consequence, an obviously distinguishable fluorescence color variation (from red to green) of the probe solution was observed. Under the optimized conditions, the developed ratiometric sensor displayed a linear response range from 0.1 to 9 μM with a detection limit of 25 nM (S/N = 3) for Cd, which could offer an alternative sensing approach for the highly sensitive and selective detection of heavy metal ions.

Dithizone-etched CdTe nanoparticles-based fluorescence sensor for the off–on detection of cadmium ion in aqueous media

“…7D, the uorescence intensity signals of the NPs mono-exponentially decayed and the uorescence lifetime of the NPs reduced from 24.3 ns to 20.3 ns aer the addition of 14 mM of DZ, which can be ascribed to the surface chemical etching of DZ around the NPs. 51 However, the uo-rescence lifetime of this NPs-DZ system increased from 20.3 ns to 22.7 ns because of the introduction of 4 mM of Cd2 + , as shown in Fig. 7D.…”

A turn‐on luminescence probe for highly selective detection of an anthrax biomarker

“…Nevertheless, there are many intrinsic disadvantages limiting their practical applications, such as lengthy cycles, complicated operation, being an expensive reagent, the high equipment cost and poor selectivity . Compared with conventional detection methods, the turn‐on lanthanide luminescence method is more suitable to the detection of Bacillus anthrax spores due to its simple operation, high sensitivity, obvious phenomenon and excellent selectivity . Europium ions produce limited luminescence due to f–f forbidden transitions.…”

Preparation of “Ion-Imprinting” Difunctional Magnetic Fluorescent Nanohybrid and Its Application to Detect Cadmium Ions

“…Compared with other organic fluorescent probes, quantum dots (QD) have been applied extensively to fluorescence detection because of their unique optical characteristics: high fluorescent quantum yield, size-adjustable fluorescence-emission peak, and multiple fluorescence colors [19,20]. Furthermore, Cd-based QD were considered for producing a surface Cd 2+ -imprinted material using EDTA as chemical etching and applied to detect Cd 2+ [12,21]. Magnetic nanoparticles are widely studied for their applications in biosensor, biology, and medicine due to excellent biocompatibility, outstanding magnetic imaging, superior separation [22,23], especially for small molecules detection, and pathogen and nonpathogen bacteria separation in a complex sample.…”