Lanthanide DO3A-tropone complexes: efficient dual MR/NIR imaging probes in aqueous medium

Area of Science:

• Coordination Chemistry
• Materials Science
• Biomedical Imaging

Background:

• Development of novel ligands for lanthanide complexes is crucial for advanced imaging applications.
• DOTA-based chelators are widely used due to their high stability.
• There is a need for imaging agents with dual modality capabilities.

Purpose of the Study:

• To synthesize and characterize a novel DOTA-based ligand incorporating a chromophoric tropone coordinating sidearm.
• To evaluate the potential of this ligand for developing dual Magnetic Resonance Imaging (MRI) and optical imaging probes.
• To investigate the properties of lanthanide complexes with the novel ligand.

Main Methods:

• Synthesis of the DOTA-based ligand with a tropone sidearm.
• Preparation and characterization of lanthanide (Ln3+) complexes.
• Relaxivity measurements (r1) for Gadolinium (Gd) complexes.
• Near-infrared (NIR) emission spectroscopy for Neodymium (Nd) and Ytterbium (Yb) complexes.

Main Results:

• A novel DOTA-based ligand (1) with a tropone coordinating sidearm was successfully synthesized.
• Gd-complex of the ligand (Gd1) exhibits relaxivity comparable to commercial MRI agents.
• The tropone moiety effectively slows water exchange, enhancing relaxivity.
• Nd1 and Yb1 complexes display significant NIR emission in aqueous solutions, with the tropone acting as an efficient sensitizer.

Conclusions:

• The novel DOTA-based ligand with a tropone sidearm is a promising platform for developing dual-mode imaging agents.
• The ligand facilitates the design of lanthanide complexes with tunable relaxivity and optical properties.
• This work paves the way for new theranostic applications in biomedical imaging.