Fabrication, characterization of spherical CaWO4:Ln @MCM-41(Ln = Eu3+, Dy3+, Sm3+, Er3+) composites and their applications as drug release systems

Spherical MCM-41 particles with a diameter of about 150 nm have been successfully coated with CaWO4:Ln (Ln = Eu3+, Dy3+, Sm3+, Er3+) phosphor layers through a simple Pechini sol–gel process. The obtained CaWO4:Ln@MCM-41 composites, which kept the mesoporous structure of MCM-41 and the luminescent properties of phosphors, were investigated as a drug delivery system using aspirin (ASPL) as a model drug. The physicochemical properties of the samples were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption, and photoluminescence (PL) spectra. The results indicate that the specific surface area and pore volume of the samples decrease after the coating of phosphors and further decrease after the loading of aspirin. In addition, this luminescent drug delivery system exhibits sustained property and the emission intensity of Eu3+ increases with the cumulative released aspirin, making it feasible to be tracked or monitored by the change of luminescence during the release process.