Progesterone inclusion into cyclodextrin-functionalized mesoporous silica

SBA-15 type mesoporous silica has been modified to produce a covalent bond with β-cyclodextrin by two different synthetic approaches to obtain an hybrid system able to work as a drug delivery system for progesterone. In the first approach, SBA-15 silica was first let to react with 3-glycidyloxypropyltrimethoxysilane to produce an epoxide ring functional group on mesoporous silica. The latter was then reacted under basic conditions with mono-6-deoxy-6-mercapto-β-cyclodextrin (β-CDCH2SH), prepared in its turn in two steps from β-cyclodextrin (β-CD) through monotosylation to give β-CDCH2OTs followed by thiolation with thiourea. In the second approach, a silica suitably functionalized with a terminal thiol group (obtained by the reaction of SBA-15 silica with 3-mercaptopropyltrimethoxysilane) was reacted with β-CDCH2OTs. The obtained materials were characterized by X-Ray powder diffraction, nitrogen adsorption, 13C Cross Polarization Magic Angle Spin Nuclear Magnetic Resonance (13C CP/MAS NMR). Progesterone was loaded on the materials producing complete filling of mesopores and cyclodextrin cavities. Its release was studied at different pH values. Only one of the two progesterone-loaded delivery device is able to retain the drug in the system during the first period at acid pH (2 h) and release it after pH increase.