Mesoporous Silica–Fe₃O₄ Nanoparticle Composites as Potential Drug Carriers

Abstract

This\nwork is an innovative study of ordered mesoporous silica (SBA-15)\nnanocomposites, with different morphologies, and superparamagnetic\niron oxide nanoparticles (SPIONs), as promising drug delivery vehicles\nguided by magnetization. Incorporating SPIONs into SBA-15 is of great\ninterest because it can improve controlled delivery of drugs as well\nas avoid agglomeration of the nanoparticles. SPIONs were prepared\nby coprecipitation and thermal decomposition methods and incorporated\ninto SBA-15, with different morphologies, by the incipient wetness\nimpregnation method. The nanocomposites (SBA-15:SPIONs) were characterized\nby physicochemical techniques, including small-angle X-ray scattering,\nX-ray diffraction, nitrogen adsorption–desorption isotherms,\nscanning and transmission electron microscopies, energy-dispersive\nspectroscopy, magnetization measurements, pair distribution function\nanalysis, Fourier transform infrared spectroscopy, thermogravimetric\nanalysis, and differential thermal analysis. The X-ray diffraction\nand small-angle X-ray scattering data of the nanocomposites verified\nthat the crystalline phase of magnetite (Fe₃O₄) and the pore structure of the SBA-15 did not undergo significant\nchanges. N₂ physisorption data evidenced significant changes\nin the textural properties of the pure SBA-15, indicating the incorporation\nof SPIONs into the mesopores, with greater incorporation when the\nnanoparticles are obtained by thermal decomposition, in agreement\nwith the small-angle X-ray scattering results. Transmission electron\nmicroscopy images, energy-dispersive spectroscopy, and thermogravimetry\nresults evidence the successful incorporation of SPIONs into the silica\nmatrix. The SBA-15:SPIONs presented superparamagnetic behavior. The\npair distribution function method revealed a significant variation\nin the local structure related to changes in the Si–Si–O\ncoordination caused by the decrease in the SBA-15 particle size. The\nincorporation of SPIONs was better for silica with smaller particle\nsizes and a higher proportion of SPIONs. Biological assays, such as\nmyelotoxicity and cell viability, demonstrated that the nanocomposites\ncould be safe potential drug delivery vehicles.