Surface-Activated Fibre-Like SBA-15 as Drug Carriers for Bone Diseases

Abstract

Here, we report an inorganic hexagonally ordered mesoporous fibre-like carrier made of silica as an effective drug delivery system with mineralisation potential. Fibre-like SBA-15 has been modified by employing a simple surface activation (rehydroxylation) procedure. The surface-rehydroxylated fibre-like SBA-15 (SBA-15-R) was used to investigate the possible mechanism of hydroxyapatite (HA) nucleation and deposition onto silica's surface after immersion in simulated body fluid (SBF). Amorphous calcium phosphate, Cadeficient HA and bone-like HA deposits were observed on SBA-15-R surface consecutively after 7, 14 and 21 days of immersion in SBF. Accordingly, our low-angle XRD, STEM and N 2 adsorption/desorption results indicated that deposited ions were mostly located at the silica's surface and could modify the size of the mesopores. The SBA-15-R was studied in vitro as the potential bioactive drug delivery system using doxorubicin (DOX) as a model water-soluble and anticancer drug. The adsorbed DOX molecules were mostly located at the pore walls and pore openings, likely together with the silanol groups. The DOX release was diffusioncontrolled and relatively slower in SBF (pH = 7.4) than in phosphate-buffered solution (pH = 5.0), most probably due to both the stronger electrostatic interactions occurring between the DOX and the SBA-15-R and the simultaneous deposition of calcium and phosphates ions from SBF.

Biphasic composite of calcium phosphate-based mesoporous silica as a novel bone drug delivery system

“…After further 14 days of pellets incubation in SBF (28 days in total), the spherical particles formed closely to each other and reorganized into the continuous layer. Based on both the results obtained for powders and our previous reports [19,20], the randomly formed clusters which spread over the pellets surface are characteristic for carbonate hydroxyapatite. Furthermore, the hydroxyapatite clusters changed their morphology after 28 days of immersion in SBF into porous, spongy-like one.…”

“…For the drug-loading experiment, the doxycycline hydrochloride (DOX, Sigma-Aldrich) was used as the model, water soluble antibiotic. For the drug-loading experiment, the immersion procedure was applied as described in our previous reports [19,20]. Briefly, DOX was first dissolved in purified water (10 mg/mL).…”

“…Ide et al [42] claimed that the calcination process of MSi results with the low concentration of surface silanol groups. Therefore, low concentration of silanols impedes the composite-DOX interactions (ionic, hydrogen bonding) which are crucial for prolonged drug delivery systems [19,20]. In case of DOX-30CaP@MSi powders, the high burst release was also the result of DOX location (at least in part) out of the pores what is characteristic for the performed adsorption method (adsorption from concentrated solution).…”

Microwave-Assisted Fabrication of Mesoporous Silica-Calcium Phosphate Composites for Dental Application

“…Therefore, two different mechanisms of hydroxyapatite formation in SBF might be observed for obtained composites: first, based on progressive dissolution/re-deposition of DCHA (SBA-CaP(MW)_S1-S2 sample) and second, related to the transformation of ACP into the apatite (SBA-CaP(MW)_S4 sample). Nonetheless, in both cases, the presence of silanol groups on the SBA-15 surface supported the apatite formation, which was proven in previous studies [ 27 , 28 , 58 ].…”

“…Additionally, the presence of SBA-15 silica in rapid coating solutions should be also considered. The residual silanol groups (Si–OH) present on the SBA-15 surface act as the nucleation centers for hydroxyapatite formation [ 28 , 58 ]. Thus, the SBA-15 surface might act as a preferable site for in situ formation of calcium phosphates during the microwave-assisted rapid coating procedure.…”