2.3. Synthesis of Amino-Functionalized Silica Nanoparticles (Si@NH2)

Silica nanoparticles (1.5 g) were added to a round bottom flask, followed by the addition of 1% APTES solution (0.5 mL APTES dissolved in 49.5 mL anhydrous toluene). The suspension was magnetically stirred at reflux temperature for 24 h. The particles were isolated by centrifugation, washed with acetone (20 mL, 3 times) and methanol (20 mL, 3 times), and dried in a vacuum oven.