Fabrication of mesoporous silica nanospheres with radially oriented mesochannels by microemulsion templating for adsorption and controlled release of aspirin

Abstract

Mesoporous silica nanospheres (MSNs) with radially oriented mesochannels were fabricated in a cetyltrimethylammonium bromide (CTAB)–ethanol–cyclohexane–water oil-in-water (O/W) microemulsion system at 35 °C by regulating ethanol-to-cyclohexane volume ratio. In addition, MSNs were obtained by introducing polyvinylpyrrolidone (PVP) as a stabilizing agent into the O/W microemulsion system. Compared with silica spheres prepared without PVP, the nanoparticle shape changed from slightly irregular spheroids to spheres, particle size decreased from 400–650 nm to 300–450 nm, and BET surface areas ranged from 1000–1114 m² g⁻¹ to 975–1052 m² g⁻¹. Based on the experimental results, a possible mechanism for the structural regulation of MSNs with radially oriented mesochannels prepared with or without PVP O/W microemulsion was proposed. Simple drug loading and release with aspirin as a model drug was performed to assess and compare the storage capacity and in vitro release profiles of the nanoparticles.