Effect of amino-functionalization on insulin delivery and cell viability for two types of silica mesoporous structures

Abstract

Inorganic mesoporous structures are a class of novel biomaterials that have shown practical applications in delivery of a variety of therapeutic agents. In the present study, two mesoporous structures were prepared, and the effect of surface modification on their insulin delivery and in vitro cytotoxicity was evaluated. Morphological and structural characterizations of silica particles were accomplished by different analytical techniques, including scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) surface area analyses. The drug loading capacity and in vitro drug release behavior of silica structures were investigated under simulated gastrointestinal conditions and phosphate-buffered saline solution using FTIR and UV–Vis spectroscopy. In vitro cytotoxicity evaluation was carried out via MTT assay. Results showed that the morphology of MCM-41 was round, while SBA-15 was wheat like, both possessed almost homogeneous size distribution. Also, modification with amine did not influence the morphology and structure of the particles. Both MCM-41 and SBA-15 particles were found to have narrow pore-size distributions of 2.8 and 6.8 nm, respectively. SBA-15 particles demonstrated a high insulin loading capacity of about 15.1 %, while MCM-41 and modified MCM-41 (mMCM-41) were observed to load virtually no insulin at all. The surface modification by amino groups resulted in higher insulin loading and the slower rate of release for modified SBA-15 (mSBA-15) compared to the non-modified SBA-15 (SBA-15). According to the cytotoxicity evaluation results, all of the samples showed cytotoxicity Grade 0–1, in a concentration-dependent manner. Moreover, insulin-loaded mSBA-15 particles exhibited higher cell viability compared to the others. It was concluded that amine modification of SBA-15 could result in higher loading and extended release of insulin and more cell viability.