A mesoporous core-shell structure for pH-controlled storage and release of water-soluble drug

A novel pH-controlled delivery system has been developed based on hollow mesoporous silica spheres using pH-sensitive polyelectrolyte multilayer coated on the spheres as a switch to store and release gentamicin molecules (a model drug). The polyelectrolyte layers with an average thickness of 12 nm was coated on hollow mesoporous silica spheres through a layer-by-layer technique. Gentamicin molecules were successfully stored in these spheres by means of adjusting the gentamicin solution from pH 2 to pH 8. The storage capacity can reach 614.8 mg/g (34.11%) at an initial gentamicin concentration of 60 mg/ml. The controlled release of gentamicin molecules from this system has been achieved by simply changing the pH value in the release media. Therefore, this type of material is of potentials for the controlled drug release applications. (c) 2007 Elsevier Inc. All rights reserved.