Fabrication of composite Fe<sub>3</sub>O<sub>4</sub>nanoparticles coupled by thermo-responsive and fluorescent Eu complex on surface
Guihua Cui, Shuguo Dong, Chunhong Sui, Toyoji Kakuchi, Qian Duan, Bo Feng
Abstract
Stimuli-responsive luminescent hybrid nanoparticles consisting of a magnetite Fe3O4 core and a hydrophilic outer shell were synthesized. The shell was a thermo-responsive Eu(III) complex shell, which was synthesized as follows: first, 3-Methacryloxypropyl-trimethoxysilane (MEMO)-co-poly(N-isopropylacrylamide) (NIPAM) (MEMO-co-PNIPAM) copolymer was prepared by free radical polymerization. Subsequently, the copolymer chelated with Europium(III) ions to form a luminescent polymeric layer. Finally, the polymeric shell was grafted onto the Fe3O4 nanoparticles surface through chemical action. The sizes of fabricated nanoparticles with core–shell structure were controlled at about 30-45 nm. The as-synthesized nanocomposite particles had excellent fluorescence performance and thermo-responsive behavior, which possessed high color purity and produced red-emission at 613 nm. The lower critical solution temperature (LCST) of thermo-sensitive magnetic nanoparticles was at around 37–38 °C. Cell viability assays suggested that these nanoparticles showed excellent biocompatibility and fluorescence-intensity in vitro.