Anti-HER2 antibody and ScFvEGFR-conjugated antifouling magnetic iron oxide nanoparticles for targeting and magnetic resonance imaging of breast cancer

Hongwei Chen,^1,* Liya Wang,^1,2,* Qiqi Yu,^1,2 Weiping Qian,³ Diana Tiwari,¹ Hong Yi,⁴ Andrew Y Wang,⁵ Jing Huang,^1,2 Lily Yang,³ Hui Mao<sup>1,2

1</sup>Department of Radiology and Imaging Sciences, ²Center for Systems Imaging, ³Department of Surgery, Emory University School of Medicine, ⁴Robert Apkarian Electron Microscopy Core, Emory University, Atlanta, GA, ⁵Ocean NanoTech LLC, Springdale, AK, USA

^*These authors contributed equally to this work

Abstract: Antifouling magnetic iron oxide nanoparticles (IONPs) coated with block copolymer poly(ethylene oxide)-block-poly(γ-methacryloxypropyltrimethoxysilane) (PEO-b-PγMPS) were investigated for improving cell targeting by reducing nonspecific uptake. Conjugation of a HER2 antibody, Herceptin^®, or a single chain fragment (ScFv) of antibody against epidermal growth factor receptor (ScFvEGFR) to PEO-b-PγMPS-coated IONPs resulted in HER2-targeted or EGFR-targeted IONPs (anti-HER2-IONPs or ScFvEGFR-IONPs). The anti-HER2-IONPs bound specifically to SK-BR-3, a HER2-overexpressing breast cancer cell line, but not to MDA-MB-231, a HER2-underexpressing cell line. On the other hand, the ScFvEGFR-IONPs showed strong reactivity with MDA-MB-231, an EGFR-positive human breast cancer cell line, but not with MDA-MB-453, an EGFR-negative human breast cancer cell line. Transmission electron microscopy revealed internalization of the receptor-targeted nanoparticles by the targeted cancer cells. In addition, both antibody-conjugated and non-antibody-conjugated IONPs showed reduced nonspecific uptake by RAW264.7 mouse macrophages in vitro. The developed IONPs showed a long blood circulation time (serum half-life 11.6 hours) in mice and low accumulation in both the liver and spleen. At 24 hours after systemic administration of ScFvEGFR-IONPs into mice bearing EGFR-positive breast cancer 4T1 mouse mammary tumors, magnetic resonance imaging revealed signal reduction in the tumor as a result of the accumulation of the targeted IONPs.

Keywords: magnetic nanoparticles, active targeting, antifouling, breast cancer, magnetic resonance imaging