Improving the controlled release of water-insoluble emodin from amino-functionalized mesoporous silica

Several types of amino-functionalized mesoporous silica, including F5-SBA-15, F10-SBA-15, and F15-SBA-15 were prepared through co-condensation of tetraethoxysilane (TEOS) and (3-aminopropyl)triethoxysilane (APTES) in varying molar ratios (5 mol%, 10 mol%, and 15 mol%) via a hydrothermal process. The materials obtained were characterized by means of small-angle X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption, Fourier transformed infrared spectra, and X-ray photoelectron spectroscopy. Increasing APTES molar ratios decreased the degree of orderliness of the functionalized mesoporous silica. Pure and amino-functionalized SBA-15 samples were employed as supports for the controlled release of water-insoluble drug emodin. Loading experiments showed that drug loading capacities mainly depended on the surface areas and pore diameters of the carriers. Controlled release profiles of emodin-loaded samples were studied in phosphate buffered saline (PBS, pH 7.4), and results indicated that the emodin release rate could be controlled by surface amino-functionalized carriers. Emodin loaded on functionalized mesoporous supports exhibited a lower release rate than that of loaded on pure SBA-15, emodin loaded on F10-SBA-15 showed the smallest release amount (71.74 wt%) after stirring in PBS for 60 h. Findings suggest that functionalized mesoporous SBA-15 is a promising carrier for achieving prolonged release time periods.