Mesoporous Silica-Fe3O4 Nanoparticle Composites as Potential Drug Carriers

This work is an innovative study of ordered mesoporous silica (SBA-15) nanocomposites, with different morphologies, and superparamagnetic iron oxide nanoparticles (SPIONs), as promising drug delivery vehicles guided by magnetization. Incorporating SPIONs into SBA-15 is of great interest because it can improve controlled delivery of drugs as well as avoid agglomeration of the nanoparticles. SPIONs were prepared by coprecipitation and thermal decomposition methods and incorporated into SBA-15, with different morphologies, by the incipient wetness impregnation method. The nanocomposites (SBA-15:SPIONs) were characterized by physicochemical techniques, including small-angle X-ray scattering, X-ray diffraction, nitrogen adsorption-desorption isotherms, scanning and transmission electron microscopies, energy-dispersive spectroscopy, magnetization measurements, pair distribution function analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential thermal analysis. The X-ray diffraction and small-angle X-ray scattering data of the nanocomposites verified that the crystalline phase of magnetite (Fe3O4) and the pore structure of the SBA-15 did not undergo significant changes. N-2 physisorption data evidenced significant changes in the textural properties of the pure SBA-15, indicating the incorporation of SPIONs into the mesopores, with greater incorporation when the nanopartides are obtained by thermal decomposition, in agreement with the small-angle X-ray scattering results. Transmission electron microscopy images, energy-dispersive spectroscopy, and thermogravimetry results evidence the successful incorporation of SPIONs into the silica matrix. The SBA-15:SPIONs presented superparamagnetic behavior. The pair distribution function method revealed a significant variation in the local structure related to changes in the Si-Si-O coordination caused by the decrease in the SBA-15 particle size. The incorporation of SPIONs was better for silica with smaller particle sizes and a higher proportion of SPIONs. Biological assays, such as myelotoxicity and cell viability, demonstrated that the nanocomposites could be safe potential drug delivery vehicles.