Design and preparation of mesoporous silica carriers with chiral structures for drug release differentiation.

In this study, twisted rod-like chiral mesoporous silicas (CMSs) with discriminating chiral characteristics (D/L) were designed and biomimetic synthesized by using L- and d-alanine derivatives as templates, and employed as poorly water-soluble chiral drug ibuprofen (IBU) carriers. The morphology and mesoscopic characteristics of CMSs were determined by transmission electron microscope (TEM) and small-angle X-ray scattering (SAXS). Meanwhile, the physicochemical properties of CMSs before and after drug loading were systematically characterized by infrared spectroscopy (IR), nitrogen adsorption, X-ray diffraction (XRD), differential scanning calorimetry (DSC) and induced circular dichroism (ICD). The results suggested that, the CMSs exhibited local chiral characteristics, which were successfully endowed by the alanine-derivative surfactants templates with a reversal of chirality. The crystalline state of IBU was effectively converted to amorphous state after being incorporated into CMSs, and the drug delivery systems shared the chiral characteristic of carriers. Besides, in vitro drug release experiments were respectively performed in simulated gastric fluid (SGF, pH 1) and simulated intestinal fluid (SIF, pH 6.8) medium, and the results demonstrated that both l-CMS and d-CMS could improve the dissolution of IBU in SGF medium, which could be explained by the amorphization of IBU. Particularly, due to the different pore geometry of these two materials, CMSs with different chirality (D/L) could be applied as carriers to accomplish drug release differentiation.