Bright,NIR‐Emitting Au23 from Au25: Characterization and Applications Including Biolabeling |
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Authors: | Madathumpady?Abubaker?Habeeb Muhammed Pramod?Kumar Verma Samir?Kumar Pal Dr R?C?Arun Kumar Soumya Paul Ramakrishnapillai?Vyomakesannair Omkumar Dr Thalappil Pradeep Prof |
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Institution: | 1. DST Unit on Nanoscience (DST UNS), Department of Chemistry, Sophisticated Analytical Instrument Facility;2. and Indian Institute of Technology Madras, Chennai 600 036 (India), Fax: (+91)?4422570509;3. Unit for Nanoscience and Technology, Department of Chemical, Biological and Macromolecular Sciences, Satyendra Nath Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India), Fax: (+91)?333353477;4. Department of Neurobiology, Rajiv Gandhi Center for Biotechnology, Thiruvananthapuram, 695014 (India), Fax: (+91)?471‐2346333 |
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Abstract: | A novel interfacial route has been developed for the synthesis of a bright‐red‐emitting new subnanocluster, Au23, by the core etching of a widely explored and more stable cluster, Au25SG18 (in which SG is glutathione thiolate). A slight modification of this procedure results in the formation of two other known subnanoclusters, Au22 and Au33. Whereas Au22 and Au23 are water soluble and brightly fluorescent with quantum yields of 2.5 and 1.3 %, respectively, Au33 is organic soluble and less fluorescent, with a quantum yield of 0.1 %. Au23 exhibits quenching of fluorescence selectively in the presence of Cu2+ ions and it can therefore be used as a metal‐ion sensor. Aqueous‐ to organic‐phase transfer of Au23 has been carried out with fluorescence enhancement. Solvent dependency on the fluorescence of Au23 before and after phase transfer has been studied extensively and the quantum yield of the cluster varies with the solvent used. The temperature response of Au23 emission has been demonstrated. The inherent fluorescence of Au23 was used for imaging human hepatoma cells by employing the avidin–biotin interaction. |
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Keywords: | core etching fluorescence gold nanostructures phase transfer |
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