Hydrophilic hybrid materials with magnetism & NIR fluorescence via surface-initiated RAFT polymerization

In the current work, one monomer (denoted as M_HB) capable of emitting near infrared (NIR) fluorescence under UV light excitation is prepared and employed to perform (co)polymerization with a commercial hydrophilic and biocompatible monomer, poly(ethylene glycol) monomethyl ether methacrylate (PEGMA), on the surface of silica coated iron oxide nanoparticles (NPs). PEGMA is used to either copolymerize or chain-extend M_HB after polymerization to improve the hydrophilicity of the NPs which is essential for practical application in bio-related areas. The as-prepared NPs in different surface modification steps were investigated by Fourier transfer infrared (FT-IR), thermogravimetric analysis (TGA), transmission electron microscope (TEM) and UV-vis spectroscopic techniques. The crystal form of the NPs was checked by powder X-ray diffraction (XRD) and it showed that the magnetic core is made up of ferroferric oxide. The magnetic properties of the NPs were measured by vibrating-sample magnetometer (VSM) and all NPs exhibited superparamagnetism. The final NPs possessing magnetic and NIR fluorescent properties have potential applications in biological areas as dual-model imaging agents, and their application as contrast agents for magnetic resonance imaging (MRI) is investigated.