Hongwei Chen1, 2, Qiqi Yu1, 2, Liya Wang1, 2, Weiping Qian3, Zehong Cao3, Lily Yang3, Hui Mao1, 2
1Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, United States; 2Center for Systems Imaging, Emory University School of Medicine, Atlanta, GA, United States; 3Surgery, Emory University, Atlanta, GA, United States
Magnetic iron oxide nanoparticles (IONPs) coated with block copolymer poly(ethylene oxide)-block-poly(-methacryloxypropyltrimeth oxysilane) (PEO-b-PMPS) that exhibit a long blood circulation time (t1/2 = 12 h) in mice and low accumulation in both the liver and spleen. Conjugation of a HER2 antibody, or a single chain fragment (scFv) of antibody against epidermal growth factor receptor (scFvEGFR) to PEO-b-PMPS coated IONPs (anti-HER2-IONPs or scFvEGFR-IONPs) results in HER2 or EGFR-targeted IONPS which specifically bind to HER2 over-expressing breast cancer cell line SK-BR-3 or EGFR positive MDA-MB-231 cells. Both antibody-conjugated and non-conjugated IONPs avoid non-specific uptake by mouse macrophages In Vitro. Magnetic resonance imaging (MRI) of the mice bearing EGFR positive human breast cancer xenografts 24 h after systemic administration of scFvEGFR-IONPs led to signal reduction in tumors as the result of accumulation of the targeted IONPs and IONP induced transverse relaxation T2 weighted contrast.