Ligand exchange on the surface of cadmium telluride quantum dots with fluorosurfactant-capped gold nanoparticles: Synthesis, characterization and toxicity evaluation

Abstract

a b s t r a c tCdTe quantum dots (QDs) can provide high-intensity and photostable luminescent signals when they are used as labeling materials for sensing trace amounts of bioanalytes. However, a major concern is whether the capping ligands of CdTe QDs cause toxic effects in living systems. In the current study, we address this problem through the complete ligand transformation of CdTe QDs from toxic thiolglycolic acid (TGA) to green citrate, which is attributed to the CdAS bond breaking and the AuAS bond formation. The highly efficient depletion of S atom from the surface of the CdTe QDs occurs after the addition of fluorosurfactant (FSN)-capped gold nanoparticles into TGA-capped CdTe QDs, accompanying with the rapid aggregation of FSN-capped gold nanoparticles via noncrosslinking mechanism in the presence of high salt. After the ligand transformation, negligible differences are observed on both photoluminescence spectra and luminescent quantum yield. In addition, the cytotoxicity of the original and new-born CdTe QDs is detected by measuring cell viability after the nanoparticle treatment. In comparison with the original TGA-capped QDs, the new-born CdTe QDs can induce minimal cytotoxicity against human hepatocellular liver carcinoma (HepG2) cells even at high dosages. Our study indicates that the extremely simple method herein opens up novel pathways for the synthesis of green CdTe QDs, and the as-prepared citrate-capped CdTe QDs might have great potential for biological labeling and imaging applications.

Turn‐off–on chemiluminescence determination of cyanide

“…Stable water‐compatible GSH‐capped CdTe QDs with an emission maximum at ~ 595 nm were used in the experiment. The concentration of prepared CdTe QD was 5.0 µmol/L, which was calculated according to the literature .…”

Removal of ammonia from aqueous solutions by ligand exchange onto a Cu(ii)-loaded chelating resin: kinetics, equilibrium and thermodynamics

“…1 to partly reveal the adsorption mechanism. The spectrum of virgin resin showed peaks at 3412 cm À1 assigned to -OH stretching vibration of hydroxyl groups; the band at 1589 cm À1 was the C]O symmetric stretching vibration of carboxylic acid groups of the virgin resin; 44,45 the peak at 2921 cm À1 is attributed to the symmetric and asymmetric C-H stretching vibration of -CH 2 and -CH 3 groups; 46 2348 cm À1 attributed the characteristic peak of -NH 2 . 1405 cm À1 assigned to bending vibrations of -OH.…”

Turn‐On Luminescent Probes for the Real‐Time Monitoring of Endogenous Hydroxyl Radicals in Living Cells

“…[6] However,awide variety of ROScan quench the fluorescence of QDs, [7] impeding the practical application of QDs as af luorescent probe for an individual ROS. [12] AU V/Vis absorption spectrum and aT EM image of the FSN-AuNPs (14 nm) are shown in Figure S3 A. Thiol-induced aggregation of the AuNPs was observed upon ligand exchange (Figure S3 B). [6c] Alternatively,t he luminescence of QDs can be recovered by the following process:T he injection of an electron from an electron-donor unit into the LUMO of aQ Dp roduces ar educing QD (QDC À ), and the injection of ahole from an electron acceptor into the HOMO of aQ Dg enerates an oxidizing QD (QDC + ); [8] the recombination of QDC À and QDC + results in the formation of excitedstate QDs,w hich can generate strong luminescence by electron-transfer recombination.…”