Multiple functionalization of SBA-15 mesoporous silica in one-pot: fabricating an aluminum-containing plugged composite for sustained heparin release

To fabricate an efficient releaser of heparin, which is an extensively used anticoagulant, aluminum containing plugged mesoporous silica SBA-15 is prepared using a one-pot synthesis process. A suitable aluminum additive in the starting mixture enables plugs to be formed inside hexagonal channels and Al species to be incorporated into the mesostructure, evidence for which is provided by powder X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), N2 sorption measurements and 27Al MAS NMR tests. Incorporation of aluminum in SBA-15 reduces the negative charge (Zeta-potential) and tailors the surface roughness of the channel through forming plugs, and the former significantly improves heparin adsorption while the latter retards heparin release. As a result, these modified composites adsorb 2–4 times more heparin than parent SBA-15 and release 60–130% more of the drug over several weeks; the sample possessing both an Al-component and plug structure can sustain release of heparin for 6 weeks, demonstrating the increased efficiency of multiply functionalized SBA-15 in the controllable release of heparin and offering a valuable clue for design of novel drug releasers.