Silica Nanoparticles were synthesized by adapting the Stöber procedure . An ethanolic mixture of ammonium hydroxide comprising 6.67 mL of ethanol, 167 µL of Milli-Q water and 2 mL of aqueous ammonia solution (25 % wt) were stirred at 25 °C and 300 rpm. 4.5 mmol of TEOS in 26.7 mL of ethanol were added at a rate of 30 mL/min, resulting in a white suspension which was maintained under stirring for 24 h. The particles were then purified by three cycles of centrifugation (14k rcf, 15 mins, 25°C) and ultrasonic redispersion (90 s), once with water (40 mL) and twice with ethanol (40 mL).