pH-Responsive Fe3O4 Nanopartilces-Capped Mesoporous Silica Supports for Protein Delivery

Delivery of proteins and peptides with excellent bioactivity and controlled release still is a great challenge nowadays. In this study, a pH-responsive delivery system obtained by anchoring 8-nm Fe3O4 nanoparticles (NPs) onto SBA-15 supports with a particle diameter in the range of 0.6-1 μm and a pore size of 6.2 nm was synthesized and investigated. The pH-stimulative response is based on the interaction between the tris(aminomethyl)ethane (TAE) groups anchored onto the pore outlet of mesoporous silica scaffolds and the carboxybenzaldehyde (CBA) groups coated on the Fe3O4 NPs, which can lead to a rapid release under the acid condition (pH = 5) and a zero release with the increase of pH value (pH = 7.4). With BMP-2 as a model protein, this Fe3O4 nanopartilces-capped mesoporous silica showed a rapid response to the change of pH for protein delivery. Furthermore, the released BMP-2 could still maintain its bioactivity and induce the osteoblast differentiation of BMSCs. Besides, the magnetic orientation mainly attributes to the Fe3O4 NPs served as the nanocaps. The excellent bio-compatibility is demonstrated by the MTT assay on BMSCs model cells. These results show that Fe3O4 NPs-capped SBA-15 materials have an effective load for large molecule size proteins, such as BMP-2, and show an excellent applied prospect in pH-responsive controlled release system.