Near infrared Ag/Au alloy nanoclusters: Tunable photoluminescence and cellular imaging

• The galvanic replacement reaction was used to prepare Ag/Au alloy NCs.
• As-prepared Ag/Au alloy NCs display near-infrared (NIR) fluorescence.
• The luminescence could be tunable from visible red (614 nm) to NIR (716 nm).
• Resultant alloy NCs was used as a probe for labeling CAL-27 cells.

The fluorescent nanomaterials play an important role in cellular imaging. Although the synthesis of fluorescent metal nanoclusters (NCs) have been developing rapidly, there are many technical issues in preparing metal alloy NCs. Herein, we used a facile galvanic replacement reaction to prepare Ag/Au alloy NCs. The characterizations of UV, PL, HRTEM, EDX and XPS confirm one fact the Ag/Au alloy NCs are carried out. As-prepared Ag/Au alloy NCs display near-infrared (NIR) fluorescence centered at 716 nm and show tunable luminescence from visible red (614 nm) to NIR (716 nm) by controlling the experimental Ag/Au ratios. Moreover, as-prepared Ag/Au alloy NCs are protected by glutathione (GSH) whose some functional groups including thiol, carboxyl and amino groups make the as-prepared alloy NCs exhibit good dispersion in aqueous solution, high physiological stability and favorable biocompatibility. Together with NIR fluorescence, these advantages make alloy NCs be promising candidate in biological labeling.

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