Mesoporous maghemite–organosilica microspheres: a promising route towards multifunctional platforms for smart diagnosis and therapy

We report facile fabrication of advanced hybrid silica–spinel iron oxide (maghemite) composite microspheres built with both superparamagnetic nanoparticles for MR imaging, hyperthermia, and a hybrid mesoporous matrix enabling the transport of bioactive molecules for in vivo biomedical applications. Elaboration of such multifunctional platforms is performed by spray drying a sol of tunable composition that allows one to control the size and amount of magnetic particles embedded in the matrix, without aggregation, and to adjust the size and the surface chemical properties of the porous silica cavities. The resulting nanocomposites (γ-Fe₂O₃ 8 nm particles in silica matrices from TEOS templated by CTAB or P123, without or with functionalisation with –Ph, –SH or –NH₂) were characterised by chemical analysis, XRD, TEM, BET, FTIR and magnetisation measurements. Tests of the materials both as MRI T₂-contrast agents and as heating sources of hyperthermia are presented in support of potential applications in diagnosis and therapy.