Lysozyme-templated gold clusters was synthesized based on the previous report. The final concentration was 150 μM and 0.625 mM for Lysozyme and Au 3+ , respectively. The pH was adjusted to 12 using 1 M NaOH, after adding Au 3+ . After 4 hours stirring at room temperature, red luminescence appeared, indicating the formation of clusters (see Figure ). The solution was purified by a 3000 Da ultrafilter tube (Sartorius) with a raw concentration of 3.3 mg/mL.