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.