Weihua Shen

Preparation of novel hollow mesoporous silica spheres and their sustained-release property

Novel hollow mesoporous silica spheres (HMSs) with uniform size and morphology have been successfully synthesized in a facile route using poly(vinylpyrrolidone) (PVP) and cetyltrimethylammonium bromide (CTAB) as co-templates at room temperature. XRD, N2 adsorption–desorption analysis, FE-SEM, and TEM are used for the characterization of the structure. The hexagonally ordered pore channels are formed on the shell. Ibuprofen (IBU) as a model drug is used to examine the storage capacity and the release behaviour of drug molecules. The storage capacity of hollow mesoporous silica spheres can reach 1133 ± 52.4 mg g−1 for ibuprofen, which is three times higher than that of conventional mesoporous materials previously reported (337 mg g−1), and the storage capacity is adjustable in a wide range. Furthermore, this system also shows a sustained-release behaviour. The release rates from the IBU-HMSs system (IBU stored in HMSs) increase with the decrease of pH values and the release process follows a Ficks law.

Immobilization of hemoglobin on stable mesoporous multilamellar silica vesicles and their activity and stability

A stable mesoporous multilamellar silica vesicle (MSV) was developed with a gallery pore size of about 14.0 nm. A simulative enzyme, hemoglobin (Hb), was immobilized on this newly developed MSV and a conventional mesoporous silica material SBA-15. The structures and the immobilization of Hb on the mesoporous supports were characterized with x-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherms, Fourier transform infrared, ultraviolet-visible spectroscopy, and so forth. MSV is a promising support for immobilizing Hb due to its large pore size and high Hb immobilization capacity (up to 522 mg/g) compared to SBA-15 (236 mg/g). Less than 5% Hb was leached from Hb/MSV at pH 6.0. The activity study indicated that the immobilized Hb retained most peroxidase activity compared to free Hb. Thermal stability of the immobilized Hb was improved by the proctetive environment of MSV and SBA-15. Such an Hb-mesoporous support with high Hb immobilization capacity, high activity, and enhanced thermal stability will be attractive for practical applications.