Aptamer-modified Magnetic Nanosensitizer for in vivo MR imaging of HER2-expressing Cancer

The aim of this study was the development of a human epidermal growth factor receptor 2 (HER2)-targetable contrast agent for magnetic resonance imaging (MRI) with a high magnetic sensitivity. An anti-HER2 aptamer-modified magnetic nanosensitizer (Apt(HER2)-MNS) was prepared by conjugation with 5′-thiol-modified aptamers and maleimidylated magnetic nanocrystals (MNCs). The physicochemical characteristics and targeting ability of Apt(HER2)-MNS were confirmed, and the binding affinity (K(d)) onto HER2 protein of Apt(HER2)-MNS was 0.57 ± 0.26 nM. In vivo MRI contrast enhancement ability was also verified at HER2+ cancer cell (NIH3T6.7)-xenograft mouse models (n = 3) at 3T clinical MRI instrument. The control experiment was carried out using non-labeled MNCs. The results indicated that up to 150% contrast enhancement was achieved at the tumor region in the T2-weighted MR images after the injection of the Apt(HER2)-MNS agent in mice that received the NIH3T6.7 cells. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s11671-018-2682-3) contains supplementary material, which is available to authorized users.