In Vivo HER2-Targeted Magnetic Resonance Tumor Imaging Using Iron Oxide Nanoparticles Conjugated with Anti-HER2 Fragment Antibody.

<bold>Purpose: </bold>The feasibility of iron oxide nanoparticles (IONPs) conjugated with anti-epidermal growth factor receptor 2 (HER2) single-chain antibody (scFv-IONPs) as novel HER2-targeted magnetic resonance (MR) contrast agents was investigated.<bold>Procedures: </bold>The scFv-IONPs were prepared and identified. For in vitro MRI, NCI-N87 (HER2 high expression) and SUIT2 (low expression) cells were incubated with scFv-IONPs. For in vivo MRI, NCI-N87 and SUIT2 tumor-bearing mice were intravenously injected with scFv-IONPs and imaged before and 24 h post-injection.<bold>Results: </bold>The scFv-IONPs demonstrated high transverse relaxivity (296.3 s-1 mM-1) and affinity toward HER2 (KD = 11.7 nM). In the in vitro MRI, NCI-N87 cells treated with scFv-IONPs exhibited significant MR signal reduction (44.6 %) than SUIT2 cells (6.8 %). In the in vivo MRI, decrease of MR signals in NCI-N87 tumors (19.3 %) was more notable than that in SUIT2 tumors (6.2 %).<bold>Conclusions: </bold>The scFv-IONPs enabled HER2-specific tumor MR imaging, suggesting the potential of scFv-IONPs as a robust HER2-targeted MR contrast agent. [ABSTRACT FROM AUTHOR]