Zinc Sensing with a Pyridine-Based Lanthanide Contrast Agent: Structural Analysis in Aqueous Solution.

Area of Science:

• Inorganic Chemistry
• Medical Imaging
• Biophysical Chemistry

Background:

• Zinc (Zn²⁺) dysregulation is linked to various diseases.
• Non-invasive imaging of zinc is crucial for diagnostics.
• Magnetic Resonance Imaging (MRI) offers a non-invasive imaging modality.

Purpose of the Study:

• To synthesize and characterize a novel Gadolinium (Gd³⁺)-based complex for Zn²⁺ sensing using MRI.
• To investigate the sensing mechanism and selectivity of the Gd³⁺ complex for Zn²⁺.
• To evaluate the potential of the complex for biological applications.

Main Methods:

• Synthesis of a novel Gd³⁺-based complex.
• Nuclear Magnetic Resonance (NMR) spectroscopy.
• Luminescence and potentiometric studies.
• Relaxivity measurements.
• Density Functional Theory (DFT) calculations.

Main Results:

• The novel Gd³⁺ complex exhibits unique behavior influenced by a short linker.
• Zn²⁺ binding significantly enhances the complex's efficacy.
• The complex demonstrates high selectivity for Zn²⁺ over other physiological cations.
• A key mechanism involves an increase in water molecules coordinated to Gd³⁺ upon Zn²⁺ binding.
• The complex maintains a strong response in the presence of Human Serum Albumin.

Conclusions:

• A novel Gd³⁺-based MRI contrast agent for Zn²⁺ sensing has been successfully developed.
• The complex's response mechanism is elucidated, highlighting increased water coordination.
• The agent's selectivity and performance in biological matrices suggest significant potential for in vivo zinc imaging.