Institute of Applied Physics and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany.
Nanoscale. 2011 May;3(5):2009-14. doi: 10.1039/c0nr00947d. Epub 2011 Feb 10.
We report a facile strategy to synthesize water-soluble, fluorescent gold nanoclusters (AuNCs) in one step by using a mild reductant, tetrakis(hydroxymethyl)phosphonium chloride (THPC). A zwitterionic functional ligand, D-penicillamine (DPA), as a capping agent endowed the AuNCs with excellent stability in aqueous solvent over the physiologically relevant pH range. The DPA-capped AuNCs displayed excitation and emission bands at 400 and 610 nm, respectively; the fluorescence quantum yield was 1.3%. The effect of borohydride reduction on the optical spectra and X-ray photoelectron spectroscopy (XPS) results indicated that the AuNC luminescence is closely related to the presence of Au(I) on their surfaces. In a first optical imaging application, we studied internalization of the AuNCs by live HeLa cells using confocal microscopy with two-photon excitation. A cell viability assay revealed good biocompatibility of these AuNCs. Our studies demonstrate a great potential of DPA-stabilized AuNCs as fluorescent nanoprobes in bioimaging and related applications.
我们报告了一种简便的策略，通过使用温和的还原剂四羟甲基氯化磷（THPC）一步合成水溶性荧光金纳米簇（AuNCs）。两性离子功能配体 D-青霉胺（DPA）作为封端剂，使 AuNCs 在生理相关的 pH 范围内具有优异的水相稳定性。DPA 封端的 AuNCs 在 400nm 和 610nm 处分别显示出激发和发射带；荧光量子产率为 1.3%。硼氢化钠还原对光学光谱和 X 射线光电子能谱（XPS）结果的影响表明，AuNC 的发光与其表面上 Au(I)的存在密切相关。在第一个光学成像应用中，我们使用双光子激发共聚焦显微镜研究了活 HeLa 细胞对 AuNCs 的内化。细胞活力测定显示这些 AuNCs 具有良好的生物相容性。我们的研究表明 DPA 稳定的 AuNCs 作为荧光纳米探针在生物成像和相关应用中具有巨大的潜力。
