Effect of the dual incorporation of fullerene and polyethyleneimine moieties into SBA-15 materials as platforms for drug delivery

Mesostructured SBA-15 silica materials have been successfully dual functionalized with polyethyleneimine (PEI) groups and C60 fullerene moieties to allow an evaluation of their properties as nanovehicles for controlled drug delivery. Methylprednisolone sodium succinate was selected as a model drug for adsorption on the surface of functionalized SBA-15 silica materials. The resulting dual-functionalized SBA-15 silica materials exhibit mesoscopic arrangements, although with a remarkable reduction in their textural properties as compared to pure silica SBA-15. The adsorption capacity of methylprednisolone on functionalized SBA-15-PEI improved remarkably compared with that of raw SBA-15, while the drug release rate slowed, as the amount of PEI anchored in the SBA-15 increased. The strong attractive electrostatic interactions between methylprednisolone and the silica surfaces of SBA-15-PEI materials, measured by zeta potential, account for these results. In a second step, wherein C60 fullerene species in combination with PEI were grafted to the silica, the results establish that the steric effects and hydrophobicity of the C60 moieties hinder methylprednisolone transport within the silica pores. The kinetic parameters obtained from the drug release profiles, fitted to four kinetic models, show that the incorporation of C60 species yields lower methylprednisolone release rates from SBA-15-PEI-C60 materials than from SBA-15-PEI materials. Additionally, the incorporation of fullerene groups into PEI-modified materials provides an increment in cell viability. Confocal microscopy evidences the cellular internalization of the dual-functionalized mesoporous SBA-15 materials inside the plasmatic membrane.