Thermosensitive and magnetic nanoparticles as “smart” drug carriers have shown great potential in the field of controlled drug delivery owing to their unique properties. Previously, poly(N-isopropylacrylamide)-coated silica/magnetic nanoparticles (PNIPAM/SiO2/Fe3O4 nanoparticles) were synthesized using SiO2-coated Fe3O4 nanoparticles as a template. The properties of these nanoparticles such as the transition of the lower critical solution temperature (LCST), biocompatibility, drug loading efficiency, and drug release kinetics were investigated in vitro for both targeted and controlled drug delivery. The release profile and the in vitro cancer cell inhibition activity of vitamin D3 loading for PNIPAM/SiO2/Fe3O4 nanoparticles were systemically studied. The loading and release behavior of vitamin D3 were found to be dependent on the LCST of PNIPAM/SiO2/Fe3O4 nanoparticles. HepG2 liver cancer cells were incubated with PNIPAM/SiO2/Fe3O4 nanoparticles loaded with vitamin D3 for 5 days, and cell viability significantly decreased, as observed by 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays, which was further confirmed by transmission electron microscopy (TEM) images. In conclusion, the current study demonstrated that PNIPAM/SiO2/Fe3O4 nanoparticles can be used as potential drug delivery systems for controlled release.
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