Poly(N-vinylcaprolactam-co-2-(diethylamino)ethylmethacrylate) Coated Fe3O4@SiO2 Core-Shell Magnetic Nanoparticles for Controlled Doxorubicin Delivery

Hybrid materials based on magnetite nanoparticles coated with silica (SiO2) and a temperature-pH dual -responsive copolymer were synthesized. First, magnetite nanoparticles (Fe3O4NPs) were functionalized with oleic acid (OA) by the coprecipitation method to give Fe3O4NPs-OA. Then, these nanoparticles (NPs) were coated with SiO2 by reverse microemulsion to obtain Fe3O4NPs@SiO2. Subsequently, Fe3O4NPs@SiO2 were modified with vinyltrimethoxysilane (VTMS) to graft poly(N-vinylcaprolactam-co-(2-(diethylamino)ethylmethacrylate) (poly(NVCL-co-DEAEMA)) by free radical polymerization. The functionalization and grafting of this copol-ymer were corroborated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermog-ravimetric analysis (TGA), vibrating sample magnetometry (VSM), and transmission electron microscopy (TEM). Doxorubicin (DOX) was loaded and then released at different pH values (7.4 and 5.0) and temperatures (25 and 37 degrees C). Overall, the release percentages were dependent on the pH, with the maximum release rate at pH 5.0 being 71%. The release kinetics study fits the Korsmeyer-Peppas model and suggests that the amount of drug released occurs by diffusion. Hemolysis test of the selected Fe3O4NPs@SiO2-g-poly(NVCL-co-DEAEMA) hybrid material showed hemolytic activity of less than 5% at concentrations up to 250 mu g/mL. These results suggest that the hybrid materials obtained may have great potential to be used as DOX nanocarriers.