Improving sensitivity of magnetic resonance imaging by using a dual-targeted magnetic iron oxide nanoprobe

Developing an ultrasensitive and high-efficient molecular imaging probe for detection of malignant tumors is extremely needed in clinical and remains a big challenge. Here, we report a novel bispecific nanoprobe for dual-targeted T2-weighed magnetic resonance imaging (MRI) of COLO-205 colorectal cancer in vivo. First, the magnetic iron oxide nanoparticles (Fe₃O₄@OA) were synthesized by a thermal decomposition method. Then, PEGylation of the hydrophobic Fe₃O₄@OA was implemented by amphiphilic DSPE-PEG2000-COOH, producing water-soluble nanoparticles (Fe₃O₄@PEG). Lastly, arginine-glycine-asparticacid-tumornecrosis factor-related apoptosis-inducing ligand (RGD-TRAIL), a bispecific fusion protein, was conjugated with the nanoparticle to construct molecularly multi-targeted nanoprobe, which was defined as Fe₃O₄@RGD-TRAIL. This Fe₃O₄@RGD-TRAIL was proven to exhibit extremely high relaxation property (r₂=534mM^-1s^-1) and saturation magnetization value (M_s=92 emu/g Fe). In vitro studies showed its dual-targeting combination capacity, favorable biocompatibility and strong ability to resist against the non-specific phagocytosis. Owing to these excellent advantages, high sensitive and efficient imaging of tumor was achieved in vivo. Therefore, this RGD-TRAIL conjugated nanoprobe could be developed as a multi-targeted contrast enhancement agent for magnetic resonance molecular imaging in detection of cancer.