中文摘要：

利用N-乙酰-L-半胱氨酸（NAC）作为稳定剂，合成了荧光性质良好的水溶性近红外发射的PbS量子点。系统考察了水相合成PbS量子点的主要影响因素，并通过TEM和XRD分别对其形貌和结构进行表征。结果表明，通过改变前体物质Pb／S，PIJ／NAC的摩尔比以及溶液的初始pH值，合成的PbS量子点显示强的近红外荧光，荧光发射峰在895nm到970urn间可调，表现出明显的量子尺寸效应。通过小鼠近红外成像实验初步证实本实验中合成的PbS量子点在生物医学成像，尤其在体内无损在位成像中具有良好的应用前景。

英文摘要：

A new facile method for preparing water-soluble near-infrared （NIR）-emitting PbS quantum dots （QDs） is proposed by using N-acetyl-L-cysteine （NAC, a derivate of L-cysteine） as its stabilizer. The influence of the precursor Pb/S molar ratio, the Pb/NAC molar ratio, and the pH of original solution on optical properties is explored. Results show that aqueous PbS QDs with strong NIR fluorescence can be prepared and their photoluminescence emission peaks can be tuned from 895 nm to 970 nm. Studies indicate that such aqueous QDs have a potential application in biomedical imaging, especially in noninvasive in vivo fluorescence imaging. In addition, the resulting PbS QDs are further characterized by a transmission electron microscopy and X-ray diffraction analysis.