Stimuli-responsive PGMA-gated mesoporous silica for controlled drug delivery

Abstract

amounts of potential π–π bonds and hydrogen bonds to load drugswith a similar structure. This allows the dissolution of poor water soluble drugs in an aqueous environment via complexation with GO. Such properties make it a promising drug carrier [2]. We report nano graphene oxide (Fig. 1a) as a novel drug carrier for benazepril (BENA) (Fig. 1a). A highly water-soluble and wellbiocompatible graphene oxide was obtained by the modified Hummers method to load Benazepril. Benazepril is poorly soluble in water, has a low absorptivity and short action time. The amount of benazepril loaded onto GO and the release of benazepril were studied. The results show that the loading capacity of benazepril (Fig. 1b) depends on the initial ratio of BENA/GO. With the increase of the initial BENA/GO ratio, the loading capacity of benazepril increases linearly and reaches 1.12 mg/mg at an initial BENA/GO ratio of 3:1. UV–vis and FT-IR spectra indicate that the loading of benazepril onto GO is based on strong π–π stacking interaction and hydrogen bond formation. AFM spectra show that the insertion of benazepril expands the space between the GO layers from 0.94 nm to 1.64 nm, indicating that the loaded benazepril is present between two GO layers. The release behavior of benazepril from GO is shown in Fig. 1c. Benazepril releases slowly from GO and the release rate gradually declines after 10 h and about 40% of the total loaded benazepril was released from the nano-composite in the first 24 h under neutral conditions (pH = 7). The release behaviors at acidic and basic conditions are similar but the total released amount of benazepril in the first 24 h is 54% and 26% at pH 2 and 10 respectively. This is due to the partial dissociation of hydrogenbonds at different pH conditions. The pH-dependent release makes it possible to release drugs at determined target organs with different pH such as the stomach and intestines. Above all, the highly efficient loading of benazepril on GO and pH-dependent release of benazepril from GO could offer a way to prepare novel GO-based drug carriers.