Synthesis of Fluorescent Gold Nanoclusters

An amount of 100 mL freshly dissolved GSH (30 mM) was mixed with an equal volume of HAuCl₄·3H₂O solution (20 mM) under stirring (500 rpm) at room temperature for 10 min. The mixture was heated to 70 °C for 12 h in a water bath with gentle stirring (500 rpm). Then, the reaction solution was kept at room temperature and shielded from light for another 12 h. After that, the generated orange-emitting AuNCs were purified according to our previous report [21 (link)]. The last step is to further purify the AuNCs aqueous solution using ultrafiltration (Millipore, Burlington, MA, USA, MWCO: 3 kDa) to remove the unreacted free ions and stock at 4 °C.