Therapeutic Nanosystem, Andalusian Centre for Nanomedicine and Biotechnology, BIONAND, Parque Tecnológico de Andalucía, Málaga, Spain.
Nanoscale. 2014 Jul 21;6(14):8091-9. doi: 10.1039/c4nr01130a.
Synthesis and characterization of gold nanoclusters (Au NCs) stabilized by a zwitterion ligand (Zw) at different Au : Zw ratios are demonstrated. Au NCs exhibit photoluminescence (PL) emission which is tunable from the near infrared (805 nm) to the red spectral window (640 nm) and strongly influenced by the ligand shell size. Optical and chemical investigations suggest the presence of gold polymeric species and large nanoclusters for a molar ratio of Au : Zw = 1 : 1. For 1 : 5 < Au : Zw < 1 : 1, Zw induces etching of the large clusters and the formation of a monolayer of the bidentate ligands on the Au NCs (cluster size ∼7 to 10 kDa) accompanied by red PL emission at λ = 710 nm. A second organic layer starts to form for larger Zw fractions (Au : Zw < 1 : 5) as a result of electrostatic and covalent interactions of the zwitterion leading to an enhancement and a blue-shift of the PL emission. The effect of temperature and pH on the optical properties of gold clusters is strongly dependent on the ligand shell and demonstrates the importance of defining gold nanoclusters as supramolecular assemblies with a complex environment.
本文展示了通过在不同的金与配体摩尔比下，利用两性离子配体稳定的金纳米簇（Au NCs）的合成与表征。Au NCs 表现出可从近红外（805nm）调谐至红光区（640nm）的光致发光（PL）发射，且强烈受配体壳层大小的影响。光学和化学研究表明，对于摩尔比 Au：Zw = 1：1 存在金聚合物种和大的纳米簇。对于 1：5 < Au：Zw < 1：1，Zw 诱导大的纳米簇的刻蚀，并在 Au NCs 上形成双齿配体的单层（簇尺寸约 7 至 10kDa），同时在 λ = 710nm 处出现红色 PL 发射。由于两性离子的静电和共价相互作用，较大的 Zw 分数（Au：Zw < 1：5）会导致第二个有机层开始形成，从而导致 PL 发射的增强和蓝移。金纳米簇的光学性质对温度和 pH 的影响强烈依赖于配体壳层，这表明将金纳米簇定义为具有复杂环境的超分子组装体的重要性。
