Synthesis, characterization and antibiotics labeling affinity of cdte quantum dots

The highly fluorescent thiol capped CdTe nanocrystals were synthesized by the aqueous synthesis route. In this method we used sodium tellurite (Na ₂TeO₃) as the Te source in contrast to the previous reported methods, which used NaHTe and H₂Te that need a pretreatment for the unstable precursor. The structure of CdTe nanocrystals was investigated by means of X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), UV-visible, Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM). The results showed the crystallinity of the CdTe nanocrystals and the average size of CdTe QDs was 3.2 nm. An aqueous solution of CdTe capped with mercaptopropionic acid (MPA) shows a characteristic fluorescent peak at 590 nm, which decrease under the influence of both the pH and temperature. The labeling affinity of the water-soluble MPA- CdTe and some selected antibiotics such as Ceftazidime and Rifampicin were investigated in 50 mM sodium acetate buffer pH 7.4. Both antibiotics show the ability to interact with QDs nanocrystal that probed by fluorescence spectroscopy. The interaction between MPA-CdTe and Rifampicin shows a dynamic quenching process while the reaction between QDs and Ceftazidime was initiated by ground-state complex formation (static quenching) .