Hybrid mesoporous silica nanospheres modified by poly (NIPAM-co-AA) for drug delivery.

The synthesis of drug delivery systems based on surface-modified mesoporous silica hollow structures remains a huge challenge. In this paper, we have obtained hollow mesoporous silica nanoparticles (MSNs) by surfactant directed sol-gel assisted hydrothermal treatment. The MSNs have the inorganic-organic hybrid frameworks with uniform diameter distribution (260 nm), and their specific surface area, mesoporous size and pore volume are 540 m2/g, 3.7 nm, 0.58 cm3/g, respectively. It was proved that the preparation of hollow ethane-bridged nanospheres with two silicon source was due to the high cross-linking of the silicone interface and hydrothermal treatment, providing a new approach for the study of drug loaded and controlled release behavior. Based on the synthesis of MSNs, MSNs were modified by methacryloxy propyl trimethoxyl silane (MPS) on the surface of MSNs. Then N-isopropylacryamide (NIPAM) and acrylic acid (AA) were grafted onto the surface of modified MSNs. The hollow ethane-bridged PNA-MSNs (poly(NIPAM-co-acrylic acid)-MSNs) with two silicon source were prepared successfully. Due to their distinctive hollow structure, PNA-MSNs demonstrated high drug encapsulation efficiency (70.4±2.9%). The experiment results proved that the modified hollow nanoparticles not only had good biocompatibility and stability, but also possessed pH-/thermal-dual responsiveness in drug release.