To a TEOS (2.5 mL) solution in 115 mL of dried ethanol, 3.75 mL of aqueous ammonium hydroxide solution (14.6 M) and 3.75 mL of water were added while stirring. After 12 h of stirring, silica nanoparticles were isolated by centrifugation at a speed of 15,000 rpm and the supernatant ...
