Large-pore mesoporous silica-coated magnetite core-shell nanocomposites and their relevance for biomedical applications

A facile synthesis for the coating of magnetic nanoparticles with large-pore, uniform mesoporous silica shells is reported. The applied procedure provides easily separable core-shell particles with discrete morphology after all production steps, crucial for any biomedical application. The large-pore sizes obtained (7 nm) paves the way for the porous shell to host also larger biomolecules than possible for standard mesoporous silica-coated particles with 3 nm pores, suitable mostly for hosting small-molecular drugs. Moreover, the synthesis is performed under neutral conditions, which prevent the magnetite (iron oxide) core from leaching/dissolving into the synthesis liquid. The same synthesis regime adapted to the corresponding standard acidic large-pore mesoporous silica synthesis conditions moreover proved to be unsuccessful, which may be a reason why syntheses of large-pore silica shells leading to discrete particles instead of particle agglomerates has to our knowledge not previously been reported in the literature.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Coating of magnetic nanoparticles with large-pore, uniform mesoporous silica shells. ► Synthesis performed under neutral conditions preserves the magnetite core. ► Shells not attainable using standard Pluronic-templated synthesis conditions. ► The large-pore sizes paves the way for the porous shell to host biomolecules. ► A highly versatile platform for functional nanomaterial engineering.