Synthesis and Characterization of PEGylated Luminescent Gold Nanoclusters Doped with Silver and Other Metals
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- 作者：Eunkeu Oh ; James B. Delehanty ; Lauren D. Field ; Antti J. Mäkinen ; Ramasis Goswami ; Alan L. Huston ; Igor L. Medintz
- 刊名：Chemistry of Materials
- 出版年：2016
- 出版时间：December 13, 2016
- 年：2016
- 卷：28
- 期：23
- 页码：8676-8688
- 全文大小：942K
- ISSN：1520-5002
文摘
Doping of fluorescent noble metal nanoclusters is being pursued to manipulate the structure of such materials along with improving physicochemical characteristics such as long-term stability and photoluminescence quantum yield. Here, we synthesize metal-doped and alloyed ultrasmall gold nanoclusters (AuNCs) directly in water using a facile one-step coreduction reaction with bidentate dithiolane PEGylated ligands that terminate in different functional groups including a methoxy, carboxy, amine, and azide. Two primary types of cluster materials were the focus of synthesis and characterization: first, a series of doped/alloyed Ag-doped AuNCs, where the ratio of Au:Ag was varied across a wide range including 99:1, 98:2, 90:10, 80:20, 50:50, 20:80, 10:90, and 2:98 along with pure AuNC and AgNC controls; second, doped Au:D NCs, where D included Pt, Cu, Zn, and Cd. Physical characterization of the modified AuNCs included TEM analysis of size, XPS/EDX analysis of dopant content, and a detailed analysis of photophysical properties including absorption and photoluminescence profiles, quantum yields over time, photoluminescence lifetimes, and examination of energy levels for selected materials. The addition of just a few Ag dopant atoms per AuNC yielded significant enhancement in quantum yield along with improving long-term photostability especially in comparison to materials with a very high Ag content. Preliminary cell imaging applications of the Ag-doped AuNCs were also investigated. Facilitated cellular uptake by mammalian cells via endocytosis following modification with cell penetrating peptides was confirmed by colabeling with specific cellular markers. Long-term intracellular photostability and lack of aggregation were confirmed with microinjection studies, and cytoviability assays showed the doped clusters to be minimally toxic.