As previous synthesis, aqueous solutions of AgNO3 (1.6 mL, 7.5 × 10 -3 M) and BSA (0.8 mL, 74 mg/mL) were mixed under vigorous stirring. After 2 min with white suspension, 0.08 mL of 1 M NaOH was added, and the solution turned to clear. Half an hour later, an aqueous solution of NaBH4 (60 µL, 112 mM, dissolved in 0.1 M. NaOH) was added, and the reaction mixture immediately changed to dark brown. The stirring continued for 1 h at room temperature. Final solution was purified using a dialysis tubing (MWCO of 50kDa). The purified BSA-AgNCs with concentration of 21 mg/mL was stored in a 4 °C fridge for later use.