Surface Design of Eu-Doped Iron Oxide Nanoparticles for Tuning the Magnetic Relaxivity

Jeong Chan Park; Gyeong Tae Lee; Hee-Kyung Kim; Bokyung Sung; Youngmi Lee; Maengjun Kim; Yongmin Chang; Jeong Hyun Seo

doi:10.1021/acsami.8b06569

Surface Design of Eu-Doped Iron Oxide Nanoparticles for Tuning the Magnetic Relaxivity

ACS Appl Mater Interfaces. 2018 Aug 1;10(30):25080-25089. doi: 10.1021/acsami.8b06569. Epub 2018 Jul 20.

Authors

Jeong Chan Park¹, Gyeong Tae Lee², Hee-Kyung Kim, Bokyung Sung³, Youngmi Lee, Maengjun Kim⁴, Yongmin Chang, Jeong Hyun Seo²

Affiliations

¹ Department of Chemical Engineering , Pohang University of Science and Technology , 77 Cheongam-Ro , Nam-Gu, Pohang , Gyeongbuk 37673 , Korea.
² School of Chemical Engineering , Yeungnam University , 280 Daehakro , Gyeongsan , Gyeongbuk 38541 , Korea.
³ Department of Medical & Biological Engineering , Kyungpook National University , 80 Daehakro , Bukgu, Daegu 702-701 , Korea.
⁴ Korea Multi-Purpose Accelerator Complex , Korea Atomic Energy Research Institute , 181 Mirae-ro , Geoncheon-eup, Gyeongju , Gyeongbuk 305-353 , Korea.

PMID: 29989402
DOI: 10.1021/acsami.8b06569

Abstract

Relaxivity tuning of nanomaterials with the intrinsic T₁- T₂ dual-contrast ability has great potential for MRI applications. Until now, the relaxivity tuning of T₁ and T₂ dual-modal MRI nanoprobes has been accomplished through the dopant, size, and morphology of the nanoprobes, leaving room for bioapplications. However, a surface engineering method for the relaxivity tuning was seldom reported. Here, we report the novel relaxivity tuning method based on the surface engineering of dual-mode T₁- T₂ MRI nanoprobes (DMNPs), along with protein interaction monitoring with the DMNPs as a potential biosensor application. Core nanoparticles (NPs) of europium-doped iron oxide (EuIO) are prepared by a thermal decomposition method. As surface materials, citrate (Cit), alendronate (Ale), and poly(maleic anhydride- alt-1-octadecene)/poly(ethylene glycol) (PP) are employed for the relaxivity tuning of the NPs based on surface engineering, resulting in EuIO-Cit, EuIO-Ale, and EuIO-PP, respectively. The key achievement of the current study is that the surface materials of the DMNP have significant impacts on the r₁ and r₂ relaxivities. The correlation between the hydrophobicity of the surface material and longitudinal relaxivity ( r₁) of EuIO NPs presents an exponential decay feature. The r₁ relaxivity of EuIO-Cit is 13.2-fold higher than that of EuIO-PP. EuIO can act as T₁- T₂ dual-modal (EuIO-Cit) or T₂-dominated MRI contrast agents (EuIO-PP) depending on the surface engineering. The feasibility of using the resulting nanosystem as a sensor for environmental changes, such as albumin interaction, was also explored. The albumin interaction on the DMNP shows both T₁ and T₂ relaxation time changes as mutually confirmative information. The relaxivity tuning approach based on the surface engineering may provide an insightful strategy for bioapplications of DMNPs and give a fresh impetus for the development of novel stimuli-responsive MRI nanoplatforms with T₁ and T₂ dual-modality for various biomedical applications.

Keywords: biosensor; dual-mode T1−T2 MRI nanoprobes; hydrophobicity; relaxivity tuning; surface design.