School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA.
Nanotechnology. 2012 Jul 11;23(27):275601. doi: 10.1088/0957-4484/23/27/275601. Epub 2012 Jun 18.
Quantum dots (QDs) are semiconducting nanocrystals that have photoluminescent (PL) properties brighter than fluorescent molecules and do not photo-bleach, ideal for in vivo imaging of diseased tissues or monitoring of biological processes. Near-infrared (NIR) fluorescent light within the window of 700-1000 nm, which is separated from the major absorption peaks of hemoglobin and water, has the potential to be detected several millimeters under the surface with minimal interference from tissue autofluorescence. Here we report the synthesis and bioimaging demonstration of a new NIR QDs system, namely, CdPbS, made by an aqueous approach with 3-mercaptopropionic acid (MPA) as the capping molecule. The aqueous-synthesized, MPA-capped CdPbS QDs exhibited an NIR emission in the range of 800-950 nm with x(i) ≥ 0.3, where x(i) denotes the initial Pb molar fraction during the synthesis. Optimal PL performance of the CdPbS QDs occurred at x(i) = 0.7, which was about 4 nm in size as determined by transmission electron microscopy, had a rock salt structure and a quantum yield of 12%. Imaging of CdPbS QDs was tested in membrane staining and transfection studies. Cells transfected with CdPbS QDs were shown to be visible underneath a slab of chicken muscle tissue of up to 0.7 mm in thickness without the use of multiple-photon microscopy.
量子点（QDs）是半导体纳米晶体，具有比荧光分子更亮的光致发光（PL）特性，并且不会光漂白，非常适合对病变组织进行体内成像或监测生物过程。近红外（NIR）荧光光在 700-1000nm 的窗口内，与血红蛋白和水的主要吸收峰分离，具有在表面下几毫米处检测到的潜力，并且最小程度地受到组织自发荧光的干扰。在这里，我们报告了一种新的近红外 QDs 系统的合成和生物成像演示，即通过水相方法用 3-巯基丙酸（MPA）作为封端分子制成的 CdPbS。水合成的、MPA 封端的 CdPbS QDs 在 800-950nm 的范围内表现出 NIR 发射，其中 x(i)≥0.3，其中 x(i)表示合成过程中初始 Pb 摩尔分数。CdPbS QDs 的最佳 PL 性能发生在 x(i)=0.7，其尺寸约为 4nm，通过透射电子显微镜确定，具有岩盐结构和量子产率为 12%。CdPbS QDs 的成像在膜染色和转染研究中进行了测试。在用鸡肌肉组织薄片进行测试时，转染了 CdPbS QDs 的细胞在没有使用多光子显微镜的情况下，在厚度达 0.7mm 的情况下可以看到。
