Multistimuli-responsive hybrid nanoparticles with magnetic core and thermoresponsive fluorescence-labeled shell via surface-initiated RAFT polymerization

Water-soluble trifunctional nanoparticles (NPs) with thermoresponsive, magnetic and fluorescent hybrid, Fe3O4@SiO2-PNIPAM, were prepared via surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, using fluorescent RAFT agent-functionalized magnetic silica NPs as the chain transfer agent and N-isopropylacrylamide (NIPAM) as the monomer. The as-prepared magnetic/fluorescent NPs with core-shell structure at different surface modification stages were characterized using UV-vis, Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), transmission electron microscope (TEM), powder X-ray diffraction (XRD) and dynamic laser light scattering (DLS) analysis. The magnetic and fluorescent properties were studied by vibrating-sample magnetometer (VSM) and fluorophotometer. Furthermore, the magnetic resonance imaging (MRI) experiment confirmed the effective imaging ability of the as-prepared ferrofluid in enhancing the negative contrast in MRI.