Aluminum powder

Materials. Tetraethyl orthosilicate (TEOS, 99.9%), ammonium hydroxide (NH4OH, 28%), magnesium -325 mesh powder (Mg, 99.8%), and aluminum powder (Al, 99.5%) were purchased from Alfa Aesar. Calcium (Ca, 99%), phosphate buffered saline (pH 7.4), ibuprofen (≥ 98%), magnesium chips (Mg, 99.98%), magnesium foil (Mg, 99.9%), aluminum granules (Al, 99.7%), aluminum foil (Al, 98%), dialysis sacks and phosphoric acid solution (H3PO4, 85%) were purchased from Sigma-Aldrich. Sodium chloride (NaCl, 99%) was purchased from Chimiques ACP Chemicals Inc. Hydrochloric acid (HCl, 36.5-38.0%) was purchased from Anachemia. Water (≥18.2 MΩ cm resistivity) was obtained from a Barnstead E-Pure system. All the reagents were used as received without further purification.
Synthesis of Stӧber silica NPs. 3.00 mL of 28% NH4OH was added to 50.0 mL of 95% EtOH and stirred together for 5 min, followed by the addition of 1.50 mL of TEOS. The reaction was stirred at 18 °C for 12 h (ambient humidity was recorded to be 82%). The silica product was collected by centrifuging at 3300 rpm for 15 min. The solid white product was washed three times with EtOH and dried overnight in an oven at 80 °C. Drug loading and release. Si-NPs (25 mg) were treated with 10 mL of 49% hydrofluoric acid solution for 15 min and collected via centrifugation.