Versatile drug releaser derived from the Ti-substituted mesoporous silica SBA-15

Abstract

Multiple modification of SBA-15 in its electrostatic and geometric properties was simultaneously performed by titanium substitution in the framework of mesoporous silica, in order to fabricate versatile drug releaser based on the Ti-SBA-15 with subtle “critical state”. The SBA-15 with proper Ti-content, no more than 4.2μmolg−1 without formation of TiO2, was synthesized via special hydrothermal conditions with assistance of fluorine ion, and the resulting composite had the appropriately distorted mesoporous structure provided the Si/Ti of initial gel no less than 50, plus the lowered surface negative charge (Zeta-potential). The controlled Ti-substitution enabled SBA-15 to be more active in adsorbing negative charged drug like heparin, especially in dilute solution. Also, sustained heparin release was achieved on the Ti-SBA-15 with a little initial burst. Ti-substitution also improved the loading and release of small drug such as ibuprofen on SBA-15, compensating the lack of fine geometric confinement in mesoporous silica. Moreover, liquid adsorption of probes with different negative charge and molecular size, including heparin, ibuprofen and volatile nitrosamines N-nitrosopyrrolidine was investigated to explore the influence of Ti-substitution on the electrostatic attraction and structural distortion of SBA-15, offering a tool to characterize the mesoporous materials and providing a valuable clue for design of new drug releaser.