Imaging Science and Photochemistry ›› 2015, Vol. 33 ›› Issue (2): 126-135.DOI: 10.7517/j.issn.1674-0475.2015.02.126

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CdTe Quantum Dots Using L-Cys/MPA as Mixed-ligands: Preparation, Characterization and Application in Cell Labeling

DING Zhaoqiang, QUAN Jing, NIE Huali, ZHU Limin   

  1. College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, P. R. China
  • Received:2014-07-31 Revised:2014-09-17 Online:2015-03-15 Published:2015-03-15

Abstract:

High-quality CdTe quantum dots (QDs) were rapidly synthesized in aqueous phase using both L-Cysteine (L-Cys) and mercaptopropionic acid (MPA) as mixed-ligands. Different technologies including UV-Vis spectra, fluorescence spectra, luminescence decay curves, transmission electron microscopy and X-ray diffraction analysis were employed to characterize the prepared QDs. The ratio of L-Cys and MPA was found to have influence on the growth kinetics and optical properties of the obtained QDs. Compared to single ligand of L-Cys or MPA, L-Cys/MPA as mixed-ligands could accelerate the red shifted rate of fluorescence emission peak wavelength effectively. CdTe QDs capped with mixed-ligands exhibited a high uniformity in diameter and an excellent photostability. 50L-CdTe (L-Cys/MPA molar ratio was 50%) held a high quantum yield of 66.4% and 75L-CdTe (L-Cys/MPA molar ratio was 75%) exhibited a luminescence decay lifetime of 46.8 ns. MTT assays showed that 75L-CdTe with emission of 615 nm maintained 75%-95% SiHa cell viability. Further study of labeling SiHa cell with the as-prepared 75L-CdTe indicated that the QDs are excellent biomarkers for SiHa cell. L-Cys and MPA as mixed-ligands with proper design can be employed to fabricate CdTe QDs with superior fluorescence properties and biocompatibility, which have potential in biological and medical fields as biomarker-candidates.

Key words: cell labeling, quantum dots, mixed-ligands, L-Cysteine, mercaptopropionic acid