Synthesis of high-quality water-soluble near-infrared-emitting CdTe quantum dots capped with 3-mercaptobutyric acid.

Kai-Guo Ma, Jin-Yi Bai, Tan Fang, Hai-Qing Guo

Index: J. Nanosci. Nanotechnol. 14(7) , 4940-8, (2014)

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Abstract

Highly fluorescent CdTe quantum dots (QDs) with emission in red to near-infrared (NIR) wavelength were successfully prepared by using 3-mercaptobutyric acid (3MBA) as capping agent. The maximum of quantum yield (QY) could reach up to 82% for QDs with emission peak at 686 nm and FWHM of 66 nm at optimal conditions. The QY of these QDs could maintain above 65% in the 650-750 nm region and QDs with emission over 800 nm were still strong fluorescent (28-41%). These optical properties of CdTe quantum dots are among the best results prepared by the state-of-the-art methods, suggesting their promising applications in bio-imaging. The success of 3MBA as excellent capping agent in this method was attributed to the balanced chain length and methyl side chain in comparison to a series of linear and branched mercapto acids, namely thioglycolic acid, thiolactic acid, 3-mercaptopropionic acid, 4-mercaptobutyric acid, 5-mercaptovaleric acid, 4-mercaptovaleric acid and 3-mercapto-2-methylbutyric acid.