Novel switchable sensor for phosphate based on the distance-dependant fluorescence coupling of cysteine-capped cadmium sulfide quantum dots and silver nanoparticles

Abstract

A novel switchable sensor was developed for the determination of phosphate based on Ce(3+) induced aggregation and phosphate triggered disaggregation of cysteine (Cys)-capped CdS quantum dots (QDs) and silver nanoparticles (AgNPs). The rare earth metal Ce(3+) could aggregate a mixture of QDs and AgNPs, which induced electron or energy transfer between CdS QDs and AgNPs and serious fluorescence quenching. However, phosphate dissociated the formed aggregation of CdS QDs and AgNPs, restoring the enhanced fluorescence of Cys-capped CdS triggered by AgNPs. Although, CdS QDs alone could also be used to detect phosphate through the aggregation-disaggregation mechanism adjusted by Ce(3+) and phosphate. It was found that the distance-dependent interaction between AgNPs and CdS QDs driven by Ce(3+) and phosphate could lead to enhanced quenching or enhancement of the fluorescence of Cys-capped CdS to form a more sensitive detection system for phosphate. The developed method was applied in the detection of phosphate in real water samples with acceptable and satisfactory results.

Energy Transfer with Semiconductor Quantum Dot Bioconjugates: A Versatile Platform for Biosensing, Energy Harvesting, and Other Developing Applications

“…Applicability to F – detection in tap water and for biological imaging was also demonstrated (Figure B). Wang et al developed a switchable sensor to detect phosphate (HPO 4 2– ) based on Ce 3+ -induced aggregation . Cysteine-capped 2.9–3.3 nm CdS QDs and either citrate or cysteine-capped AgNPs (diameter: 5–15 nm) aggregated in the presence of Ce 3+ accompanied by strong fluorescence quenching through either e T or ET.…”

“…Wang ) based on Ce 3+ -induced aggregation. 764 Cysteine-capped 2.9−3.3 nm CdS QDs and either citrate or cysteine-capped AgNPs (diameter: 5−15 nm) aggregated in the presence of Ce 3+ accompanied by strong fluorescence quenching through either eT or ET. Introduction of HPO 4 2− dissociated the aggregates, restoring the QD PL.…”

Surface Decoration of Organic Ligands on Quantum Dots: Fine Tuning of Photophysical Properties

“…14). Wang et al developed a sensor for the detection of phosphate ion based on aggregation-disaggregation sequence of cysteine (Cys)-capped CdS quantum dots (QDs) and Cit-capped silver nanoparticles (AgNPs) which adjusted the interparticle distance and fluorescence coupling of QDs and AgNPs Handbook of Nanoparticles DOI 10.1007/978-3-319-13188-7_51-1 # Springer International Publishing Switzerland 2015 [56]. At optimum concentrations of Cys-capped CdS QDs and Cit/Cys-capped AgNPs in aqueous medium, fluorescence intensity of Cys-capped CdS QDs enhanced due to the presence of local enhanced electromagnetic field around AgNPs.…”

Engineering the Self-Assembly Induced Emission of Copper Nanoclusters as 3D Nanomaterials with Mesoporous Sphere Structures by the Crosslinking of Ce3+

“…Herein, we found a method for assembling CuNCs into well-ordered mesoporous spheres by the binding ability of metal ions with l -cysteine-protected nanomaterials. 24 The structures of the aggregates could be adjusted to a controllable form by tuning the amounts of Ce 3+ . The mechanism is described in Scheme 1.…”

“…Consequently, exploring a protocol for aggregating NCs as appropriate structures is of great importance. Herein, we found a method for assembling CuNCs into well-ordered mesoporous spheres by the binding ability of metal ions with l -cysteine-protected nanomaterials . The structures of the aggregates could be adjusted to a controllable form by tuning the amounts of Ce 3+ .…”