Facile and Novel Synthesis of MR/NIR Dual Modal Contrast Agent for In Vivo Non-invasive Molecular Imaging

Nanoprobes that are used for biomedical applications usually require surface modifications using amphiphilic surfactants or inorganic coating materials to enhance their biocompatibility. We proposed a facile synthetic approach... [ view full abstract ]

Nanoprobes that are used for biomedical applications usually require surface modifications using amphiphilic surfactants or inorganic coating materials to enhance their biocompatibility. We proposed a facile synthetic approach for the phase transfer of hydrophobic magnetic nanoparticles by the direct adherence of fluorescent probes, without any chemical modifications, for use as a magnetic resonance (MR)/near-infrared (NIR) fluorescence bimodal imaging contrast agent. Indocyanine green (ICG) was used not only as an optical component for NIR imaging, but also as a surfactant for phase transfer with no superfluous moiety, which we call ‘ICGylation’. Cell labeling and tracking in vivo with ICGylated magnetic nanoparticles were successfully performed by MR/NIR dual-modal imaging for three days, which shows great biostability without any additional surface functionalization. We expect that this novel MR/NIR contrast agent with sensitive detection and simultaneous imaging capability can be used in diverse fields, such as the imaging and tracking of immune cells to confirm immunotherapeutic efficacy. This approach could also be applied to other kinds of nanoparticles, and it would promote development of advanced functional multimodal nanobioprobes.