Lanthanide(III)-based complexes for potential dual 1H/19F MRI contrast agents: Synthesis, structure, relaxivity and 19F NMR spectroscopy studies

Abstract

Magnetic resonance imaging (MRI) is an effective technique for diagnosing diseases. Its most used modality is based on the T₁-weighted contrast but is limited by the background signal of water in the tissue. A combination of different MR imaging modalities together can reduce this consideration and exclude background interference. Paramagnetic lanthanide cations have versatile magnetic and optical characteristics along with similar reactivities; hence, their complexes are good candidates as multimodal agents. Also, fluorinated probes are gaining increasing attention for the use due to the advantageous features of ¹⁹F MRI. Herein, the prototypes of LnDO3A-based fluorine-containing complexes were developed, providing potential detection by T₁-weighted (Gd³⁺ complex) and ¹⁹F-based (Y³⁺, Eu³⁺ and Yb³⁺ complexes) MRI, or by means of optical imaging using lanthanide-based luminescence in the visible range (Tb³⁺ complex). The use of different Ln³⁺ ions causes only minor changes in the structure of complexes, while these probes are predicted to possess comparable structural stability while performing experiments with different imaging modalities.