Bimodal mesoporous materials were modified with different amount of 3-aminopropyltriethoxysilane and employed as aspirin carriers. The modified and drug loaded bimodal mesoporous materials were characterized with XRD, FT-IR, TEM and elemental analysis methods to explore the influence of amino groups and drug molecules on the mesoporous surface. Meanwhile, the mesoporous surface energy states was calculated by the density functional theory based on the N-2 sorption analysis. According to the surface energy distributions of samples including before and after modification and drug loading, it can be deduced that through superficial modification with amino groups, the surface energy moves to high state, implying the introduction of amino moieties could provide the mesoporous surface with much active sites. Besides, the interaction between the amino groups and drug molecules is weak, and hence the controlled drug delivery would be possible. (C) 2011 Elsevier Ltd. All rights reserved.