Preparation and Characterization of Water-Soluble Near-infrared Emitting PbS Quantum Dots

摘要

In this paper, we report a new facile method to prepare water-soluble near-infrared (NIR)-emitting PbS quantum dots (QDs), using N-acetyl-L-cysteine (NAC, a derivate of L-cysteine) as its stabilizer. We explored intensively the influence of the precursor Pb/S molar ratio, the Pb/NAC molar ratio, and the pH of original solution on optical properties. The results showed that aqueous PbS QDs with strong NIR fluorescence could be prepared, and their photoluminescence emission peaks could be tuned from ~895 nm to 970 nm. The preliminary studies have indicated that such aqueous quantum dots have a potential application in biomedical imaging, especially in noninvasive in vivo fluorescence imaging. In addition, the resulting PbS quantum dots were further characterized by transmission electron microscopy and X-ray diffraction analysis.