Characterization of the Nuclear Magnetic Resonance Relaxivity of Gadolinium Functionalized Magnetic Nanoparticles

Abstract

The need to develop specific magnetic nanostructures for resonance imaging becomes more evident by the day. In this study, iron oxide magnetic nanoparticles stabilized with ethylenediaminetetraacetic acid (EDTA), followed by a gadolinium (Gd) ion chelation reaction Gd-EDTA-MNPs were synthesized and evaluated as a potential magnetic resonance imaging contrast agent. The contrast agent has been developed by a facile and universal coordination chemistry method. The compositions, structures, as well as the physicochemical characterization techniques, are reported. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrate the success of gadolinium complexation by the carboxyl group of EDTA coated iron oxide nanoparticles. Cytotoxicity measurements have been performed using a cell culture of normal human keratinocytes (HaCaT cell line) and human malignant melanoma (A375). Our results show a significant increase in the transverse relaxivity induced by the complexation with gadolinium, 540 mM⁻¹ s⁻¹ for Gd-EDTA-MNPs. The longitudinal relaxation dispersion curves show one order of magnitude enhancement of the longitudinal relaxivity from 2.2 mM⁻¹ s⁻¹ (EDTA-MNPs) to 29.6 mM⁻¹ s⁻¹ (Gd-EDTA-MNPs) at a 20 MHz resonance frequency. The results suggest that Gd complexation may represent a viable approach in obtaining contrast agents able to reduce both T₁ and T₂ nuclear relaxation times.

Keywords:

• Ethylenediaminetetraacetic acid
• gadolinium ions
• magnetic nanoparticles
• magnetic resonance relaxometry

Acknowledgments

We thank Dr. Sesarman Alina from Babes-Bolyai University for the HaCaT cell line gift.

Additional information

Funding

This work was supported by a grant of the Romanian Ministry of Research and Innovation, PCCCDI – UEFISCDI, project number PN-III-P1-1.2-PCCDI-2017-0769, contract number 64, within PNCDI III. The mobility of Alexandrina Nan was funded by the Ministry of Research and Innovation, through the project 32PFE/19.10.2018.