The interaction of MRI contrast agents with phospholipids

Area of Science:

• Biophysics
• Magnetic Resonance Imaging (MRI)
• Materials Science

Background:

• MRI contrast agents are routinely used in clinical diagnostics.
• Understanding their interaction with biological membranes is essential for safety and efficacy.
• Lipid vesicles composed of egg phosphatidylcholine (EPC) serve as model systems for biological membranes.

Purpose of the Study:

• To investigate the molecular interactions between clinically used MRI contrast agents and EPC lipid vesicles.
• To elucidate how contrast agent properties influence these interactions.
• To correlate NMR findings with the structure of the phospholipid-water interface.

Main Methods:

• High-field Nuclear Magnetic Resonance (NMR) spectroscopy was employed.
• Proton resonance line width and T1 relaxation times of lipid head groups were measured.
• Experiments were conducted at a specific molar ratio of contrast agent to phospholipid (1:5).

Main Results:

• Significant increases in proton resonance line width and decreases in T1 relaxation times were observed for lipid head groups.
• These NMR effects were independent of the contrast agents' ionic status and chelate structure.
• The magnitude of NMR changes varied with contrast agent structure and lipid head group location, being greatest at the vesicle-water interface.

Conclusions:

• MRI contrast agents interact with phospholipid head groups at the vesicle-water interface.
• The observed NMR changes provide insights into the structure of the phospholipid-water interface.
• Findings are relevant for improving MRI diagnostics and designing novel contrast agents for physiological surfaces.