Application of magnetic targeted fluorescence/magnetic resonance dual-modal imaging in cancer diagnosis

We designed a new nanoprobe—NPAPF-Fe₃O₄ NPs (about 150 nm)—with magnetic targeting fluorescence/magnetic resonance dual-mode imaging by using the combination of an AIE dye NPAPF (bis(4-(N-(2-naphthyl)phenylamino) phenyl)-fumaronitrile) and Fe₃O₄ NPs. The size of the NPAPF-Fe₃O₄ NPs was about 150 nm. This design successfully overcame the fluorescence quenching of the organic fluorescent dyes in the presence of metallic materials, which could be used for imaging applications. Under the premise of ensuring fluorescence imaging, we introduced the magnetic resonance imaging contrast agent Fe₃O₄ NP with higher spatial resolution and high sensitivity, and also a magnetic field–assisted targeting effect. After the surface modification, the NPAPF-Fe₃O₄ NPs showed good dimensional stability, biocompatibility, and biosafety, and had a longer blood circulation time in vivo. The NPAPF-Fe₃O₄ NPs were used to study the in vivo and in vitro fluorescence imaging and in vitro magnetic resonance imaging. The results showed that the fluorescence intensity of NPAPF-Fe₃O₄ NPs was lower than that of NPAPF NPs at the same concentration in cell imaging experiments. However, due to the appropriate Fe₃O₄ NP doping ratio, better fluorescence imaging could be achieved by NPAPF-Fe₃O₄ NP both in vitro and in vivo. In addition, in vitro magnetic resonance imaging showed a linear relationship between the 1/T₂ of NPAPF-Fe₃O₄ NPs and the concentration of Fe, which was a T₂ contrast agent capable of magnetic resonance imaging.