Synthesis of novel fluorescent magnetic nanoparticles as bimodal imaging agents

Abstract

Inorganic/organic nanoparticles are emerging probes for the biomedical applications. Especially, magnetic nanocrystals (MNCs, Fe3O4) have recently demonstrated excellent magnetic properties and low toxicity that can be applied to bio-medical applications such as magnetic resonance (MR) imaging systems (Lee et al., 2000; Yang et al., 2007). Due to advantageous bimodal imaging for synergistic target disease diagnosis, moreover, fluorescent-dye as optical imaging agents was introduced to MNCs and well-tailored fluorescent magnetic nanoparticles (FMNs) were synthesized using polymethyl methacrylate (PMMA). Inorganic/organic nanocomposites containing 10 nm of MNCs (Fig. 1a) and fluorescent rhodamine B were fabricated by a simple way (nano-emulsion method) using PMMA as substrate. The prepared nanocomposites have a homogeneous size of 80 nm (Fig. 1b). In the spin–spin relaxation time (T2) weighted MR images, FMNs solution presented high relaxivity coefficient (720.62 mM−1 s−1) because large amounts of magnetic components incorporate with the PMMA (Fig. 1c). Furthermore, the potentials of FMNs as optical imaging agents were estimated using optical imaging equipments. FMNs were successfully gathered by external magnetic field and that was visualized with color maps (Fig. 1d). Conclusively, FMNs, as bimodal imaging agents, not only demonstrated excellent sensitivity as MR probes but also produced clear fluorescent intensity as optical imaging probes