Functionalized Large-Pore Mesoporous Silica Microparticles for Gefitinib and Doxorubicin Codelivery.

Large-pore coralline mesoporous silica microparticles (CMS) were synthesized using the triblock polymer PEG--PEO--PEG and a hydrothermal method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the coralline morphology of the fabricated materials. The Brunauer⁻Emmett⁻Teller (BET) method and the Barrett⁻Joyner⁻Halenda (BJH) model confirmed the existence of large pores (20 nm) and of a tremendous specific surface area (663.865 m²·g) and pore volume (0.365 cm³·g). A novel pH-sensitive multiamine-chain carboxyl-functionalized coralline mesoporous silica material (CMS⁻(NH)₃⁻COOH) was obtained via a facile "grafting-to" approach. X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) validated the effective interfacial functionalization of CMS with carboxyl and multiamine chains. The encapsulation and release behavior of the dual drug (gefitinib (GB) and doxorubicin (DOX)) was also investigated. It was found that CMS⁻(NH)₃⁻COOH allows rapid encapsulation with a high loading capacity of 47.36% for GB and 26.74% for DOX. Furthermore, the release profiles reveal that CMS⁻(NH)₃⁻COOH can preferably control the release of DOX and GB. The accumulative release rates of DOX and GB were 32.03% and 13.66%, respectively, at a low pH (pH 5.0), while they reduced to 8.45% and 4.83% at pH 7.4. Moreover, all of the modified silica nanoparticles exhibited a high biocompatibility with a low cytotoxicity. In particular, the cytotoxicity of both of these two drugs was remarkably reduced after being encapsulated. CMS⁻(NH)₃⁻COOH@GB@DOX showed tremendously synergistic effects of the dual drug in the antiproliferation and apoptosis of A549 human cancer cells in vitro.