One step synthesis of bright luminescent core/shell CdTexS1-x /ZnS quantum dots emitting from the visible to the near infrared
Résumé
A one-pot synthetic approach was developed to prepare water-dispersible core/shell CdTexS1-x/ZnS QDs using CdCl2, Zn(OAc)2, NaHTe and 3-mercaptopropionic acid (MPA) as starting materials. Sulfide S2- ions produced from the partial decomposition of MPA associate to CdTe nuclei to form an alloyed CdTexS1-x core before reacting with Zn2+ ions to generate the ZnS shell. The photoluminescence (PL) of CdTexS1-x/ZnS QDs QDs can be adjusted from the green to the near-infrared region by varying the ratio of precursors or the reaction time. The formation of core/shell CdTexS1-x/ZnS structure was confirmed by high resolution transmission electron microscopy and X-ray diffraction studies. The highly luminescent QDs (PL quantum yields up to 35%) exhibit good stability in aqueous solution and low cytotoxicity towards Kluyveromyces bulgaricus cells. Bioconjugation of CdTexS1-x/ZnS QDs with (D)-(+)-galactose was successfully applied for the fluorescent imaging of the yeast cells.