Thiol-Directed Synthesis of Highly Fluorescent Gold Clusters and Their Conversion into Stable Imaging Nanoprobes

Authors

  • Sharbari Palmal,

    1. Centre for Advanced Materials, Indian Association for the Cultivation of Science, Kolkata 700032 (India), Fax: (+91) 33-24732805
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  • SK Basiruddin,

    1. Centre for Advanced Materials, Indian Association for the Cultivation of Science, Kolkata 700032 (India), Fax: (+91) 33-24732805
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  • Amit Ranjan Maity,

    1. Centre for Advanced Materials, Indian Association for the Cultivation of Science, Kolkata 700032 (India), Fax: (+91) 33-24732805
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  • Dr. Sekhar C. Ray,

    1. School of Physics, University of the Witwatersrand, Private Bag 3, Wits-2050, Johannesburg (South Africa)
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  • Dr. Nikhil R. Jana

    Corresponding author
    1. Centre for Advanced Materials, Indian Association for the Cultivation of Science, Kolkata 700032 (India), Fax: (+91) 33-24732805
    • Centre for Advanced Materials, Indian Association for the Cultivation of Science, Kolkata 700032 (India), Fax: (+91) 33-24732805
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Abstract

Fluorescent gold clusters (FGCs) with tunable emission from blue to red and quantum yields in the range of 6–17 % have been synthesized by simple modification of the conditions used for the synthesis of gold nanoparticles, namely by replacing the stronger reducing agent with a controlled amount of thiol. Various functional FGCs with hydrodynamic diameters of 5–12 nm have been successfully synthesized and used as cell labels. The results of our investigations strongly indicate that FGCs composed of Au0 are more stable imaging probes than commonly reported red/NIR-emitting FGCs with a composition of Au0/AuI, as this combination rapidly transforms into nonfluorescent large clusters on exposure to light. The FGC-based nanoprobes reported herein exhibit stable fluorescence upon continuous light exposure and can be used as imaging probes with low cytotoxicity.

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