Preparation of mesoporous silica microspheres with multi-hollow cores and their application in sustained drug release

Abstract

Mesoporous silica microspheres with multi-hollow cores (MSMMCs) were prepared by an O 1/W/O 2 double emulsion technique. When tetraethyl orthosilicate (TEOS) was hydrolyzed in the O 1/W/O 2 double emulsion with P123 (a triblock copolymer with a formula of HO(CH 2CH 2O) 20(CH 2CH(CH 3)O) 70(CH 2CH 2O) 20H) dissolved in the aqueous phase, the internal oil droplets would serve as templates for the empty hollow cores, P123 function as templates for the mesopores in the shell, and the aqueous phase act as space-limiting micro-reactors for the hydrolysis process, thus forming MSMMCs with controllable size and hollow cores. After further modification by a high-temperature aging process, the prepared MSMMCs had a diameter of 2–10 μm, with macro-multi-hollow cores with a size of 100–1000 nm, mesopores in the shell with a size of 3.8–4.4 nm, and a surface area of 383–735 m 2/g. In addition, MSMMCs were used as carriers to load avermectin through an immersing and evaporating process, and the loaded avermectin showed a well sustained release behavior from the MSMMCs matrix. This study demonstrated a promising and simple method for preparing silica micro-particles with porous multi-hollow core structure for sustained release applications.