Quenching of the Luminescence of Upconverting Luminescent Nanoparticles by Heavy Metal Ions

Abstract

We report that the luminescence of upconverting luminescent nanoparticles (UCLNPs) is quenched by heavy metal ions and halide ions in aqueous solution. The UCLNPs consist of hexagonal NaYF(4) nanocrystals doped with trivalent rare earth ions and were synthesized by both the oleic acid (solvothermal) method and the ethylenediaminetetraacetic acid (co-precipitation) method. Quenching was studied for the Cu(II), Hg(II), Pb(II), Cd(II), Co(II), Ag(I), Fe(III), Zn(II), bromide, and iodide ions and is found to be particularly strong for Hg(II). Stern-Volmer plots are virtually linear up to quencher concentrations of 10-25 mM, but deviate from linearity at higher quencher concentrations, because static quenching causes an additional effect. The UCLNPs display two main emission bands (blue, green, red or near-infrared), and the quenching efficiencies for these are found to be different. The effect seems to be generally associated with UCLNPs because it was observed for all UCLNPs doped with trivalent lanthanide ions including Yb(III), Er(III), Ho(III), and Tm(III). The results are discussed in terms of quenching mechanisms and with respect to potential applications such as optical sensing.

Electrochemically assisted flexible lanthanide upconversion luminescence sensing of heavy metal contamination with high sensitivity and selectivity

“…Lifetime shis indicate that dynamic quenching processes are largely responsible for the detections, while the lifetime recoveries at high [Cu 2+ ] are ascribed to the increasing signicance of the static quenching factor. 19,20 The ndings are in agreement with the SV analysis as discussed. In view of a small spectral overlap of the metal ion absorbance and 615 nm UCL, radiative processes such as LRET and the inner lter effect less likely dominate the UCL deactivation.…”

“…S16, † the optical responses were rather sensitive to most of the tested non-specic cations at 0 V. The inferior selectivity is attributed to the lack of Cu 2+ -responsive molecules on the nanophosphors and the efficient electron transfer to the transition metal ions leads to observable UCL quenching effects. 20 In particular, Ni 2+ and Cr 3+ ions exhibited relatively Black bars correspond to the single-ion system while red bars correspond to the co-existing non-specific cation/Cu 2+ ion system. All error bars were obtained from three separated experiments ( better quenching capability among the hazardous cations which are at low concentrations.…”

Photonen aufkonvertierende Nanopartikel zur optischen Codierung und zum Multiplexing von Zellen, Biomolekülen und Mikrosphären

“…[61][62][63] Eine dritte Art von Schwankungen in der Lumineszenzintensität der UCNPs wird durch Oberflächeneffekte verursacht. [64] [66] Die Herstellung kleinerer UCNPs führt normalerweise zu verstärkten Lçscheffekten auf der Oberfläche, da das Volumen stärker mit dem Radius abnimmt als die Oberfläche. Demgegenüber sind für viele bioanalytische Anwendungen kleine UCNPs erforderlich.…”

“…Die einzigen Parameter, die die Lumineszenz der UCNPs direkt beeinflussen, sind die Temperatur, [62,63,193,194] mit einigen Einschränkungen der pH-Wert [139] und einige Schwermetallionen. [66] Die Detektion von nahezu jedem anderen intrazellulären Analyten erfordert, dass die Oberfläche der UCNPs mit einem analytspezifischen organischen Farbstoff ausgestattet wird, der z. B. durch das Emissionslicht der UCNPs angeregt wird.…”

“…UCNPs in Sensorfilmen wurden zur vollständig reversiblen Beobachtung von Ammoniak, [235] Kohlendioxid, [236] Sauerstoff, [237] pH-Wert [238] und Schwermetallionen [66,239] in Echtzeit eingesetzt. UCNPs werden zwar nicht direkt von Analyten beeinflusst, kçnnen aber als Nanolichtquellen fungieren, deren Emission durch einen zugesetzten Indikator verändert wird.…”