Synthesis, characterization and in vitro toxicity assessment of DMPS-capped CdTe quantum dots

摘要

The title water-soluble thiol-capped QDs (quantum dots) were synthesized by reacting CdCl_2, DMPS and NaHTe in a water medium [DMPS is sodium 2,3-bis(sulfanyl)propane-1-sulfonate]. The nanoparticles were characterized by UV-Vis, fluorescence and FT-IR spectroscopy, transmission electron microscopy (TEM) and powder XRD measurements. The QDs are spherical, with an average diameter of 3.4 ± 0.7 nm and good stability against photooxidation and photobleaching. The influence of a wide number of anions and cations on the fluorescence emission of the nanoparticles has been explored. At a low metal cation concentration (5 μM), only Hg(II) produces the total quenching of the QD photoemission. At higher concentrations, Cu(II), Ag(I), Pb(II) and Ni(II) also induce a significant quenching. A preliminary analysis of the QD cytotoxicity on HeLa 229 and LLC-PK1 line cells was performed using the MTT assay. In 2 h incubation experiments, high cell-viability was observed, but this parameter decreases significantly after 24 h incubation. During this longer incubation period only the LLC-PK1 cells maintained a good metabolic activity when [QDs] is ≤5 μg/mL. Accordingly, fluorescence confocal microscopy indicated that the uptake of the nanoparticles is apparently higher in HeLa cells than in LLC-PK1 cells.