Related Experiment Video
Updated: Dec 7, 2025
Biofunctionalized Prussian Blue Nanoparticles for Multimodal Molecular Imaging Applications
Published on: April 28, 2015
A Second Generation Mn-Porphyrin Dimer with a Twisted Linker as a Potential Blood Pool Agent for MRI: Tuning the
Hanlin Liu1,2, Weiran Cheng1,2, Shili Dong2
1Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada.
Abstract:
Blood-pool agents (BPAs) are MRI contrast agents (CAs) characterized by their long circulation in the vascular system to provide an extended time window for high-resolution MR angiography (MRA). Prolonged vascular retention, however, impedes the excretion of BPAs. Therefore, chemical strategy to regulate the balance between retention and clearance is important to reach optimal pharmacokinetics. We recently developed MnP2, the first Mn(III)-porphyrin (MnP) based BPA. MnP2 shows high T1 relaxivity (r1) and high affinity to human serum albumin (HSA) that leads to up to 48-h vascular retention in rats. However, upon albumin binding, the r1 is decreased. To modulate vascular retention time and plasma r1, a regioisomer of MnP2, m-MnP2, was synthesized. The free m-MnP2 exhibits lower r1 than that of MnP2 at magnetic fields above 2 MHz, which agrees with their relative hydrodynamic sizes. The HSA binding of m-MnP2 was evaluated using UV-Vis spectroscopy and found to have tuned-down affinity in comparison with MnP2. Upon HSA binding, the protein complex of m-MnP2 exhibits an r1 of 11.8 mM-1 s-1 at 3 T, which is higher than that of MnP2 bound to HSA. Taken together, this demonstrated the role of molecular geometry in optimizing the pharmacokinetics of albumin-targeting BPAs.
Insights
Researchers modified a manganese(III)-porphyrin blood-pool agent (BPA) to optimize its circulation time and MRI contrast properties. The new regioisomer, m-MnP2, shows improved relaxivity after binding to human serum albumin (HSA), balancing retention and clearance for better MR angiography.
Area of Science:
- Biomedical Imaging
- Materials Science
- Pharmacokinetics
Background:
- Blood-pool agents (BPAs) are crucial for high-resolution MR angiography (MRA) due to their prolonged vascular circulation.
- Optimizing the balance between BPA vascular retention and excretion is essential for effective pharmacokinetics.
- Previous manganese(III)-porphyrin (MnP) based BPA, MnP2, exhibited long retention but reduced relaxivity upon albumin binding.
Purpose of the Study:
- To synthesize and evaluate a regioisomer of MnP2, termed m-MnP2, to modulate vascular retention time and plasma relaxivity.
- To investigate the impact of molecular geometry on the pharmacokinetic properties of albumin-targeting BPAs.
Main Methods:
- Synthesis of the regioisomer m-MnP2.
- Evaluation of T1 relaxivity (r1) of free and albumin-bound forms across various magnetic fields.
- Assessment of human serum albumin (HSA) binding affinity using UV-Vis spectroscopy.
Main Results:
- Free m-MnP2 showed lower r1 than MnP2 at magnetic fields above 2 MHz, consistent with hydrodynamic size differences.
- m-MnP2 exhibited a tuned-down affinity for HSA compared to MnP2.
- Albumin-bound m-MnP2 demonstrated a higher r1 (11.8 mM⁻¹ s⁻¹ at 3 T) than albumin-bound MnP2.
Conclusions:
- Molecular geometry plays a significant role in optimizing the pharmacokinetics of albumin-targeting BPAs.
- m-MnP2 represents a promising candidate for MR angiography with improved relaxivity upon HSA binding.
- This study provides insights into designing next-generation contrast agents by controlling molecular structure and protein interactions.
More Related Videos
13:21Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
Published on: July 21, 2011
11:27Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging
Published on: December 4, 2016
