Fe(III) Macrocyclic MRI Contrast Agents With Stable High-Spin Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gadolinium(III) MRI contrast agents pose toxicity risks for a significant portion of the population, and current iron(III) alternatives suffer from issues such as ROS generation, insolubility, and difficulty in synthetic modification, necessitating improved Fe(III) complexes for MRI contrast agents.
Innovation Solution
Development of high-spin Fe(III) macrocyclic complexes with controlled spin and oxidation states, enhanced solubility, and stability, utilizing macrocyclic ligands to stabilize Fe(III) and enhance T1 relaxivity as MRI contrast agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gadolinium(III) contrast agents are used, then MRI contrast effectiveness is improved, but patient safety deteriorates due to toxicity and Gd deposition
Solution Approach 1:
The patent changes the metal ion parameter from gadolinium(III) to iron(III), utilizing the endogenous nature of iron to eliminate toxicity concerns while maintaining MRI contrast functionality. The macrocyclic ligand structure is optimized to control iron's spin and oxidation states, ensuring both safety and imaging effectiveness.
Solution Approach 2:
The patent employs iron(III), an endogenous metal ion that is naturally present in the body and metabolizable, replacing gadolinium which accumulates in tissues. This approach uses a biocompatible, short-lived contrast agent that does not persist in the body, eliminating long-term deposition risks.
2Ease of manufacture
If simple linear chelates are used for Fe(III) contrast agents, then ease of manufacture is improved, but reliability deteriorates due to ROS generation and insolubility
Solution Approach 1:
The patent combines iron(III) with macrocyclic ligands containing specific donor atoms (N, O, S) to create a composite coordination complex. This composite structure provides both synthetic accessibility and enhanced reliability by controlling iron's redox potential, preventing ROS generation, and improving water solubility through pendant functional groups.
Solution Approach 2:
The macrocyclic ligand structure incorporates different donor atoms (nitrogen, oxygen, sulfur) at specific positions around the iron center, creating local electronic environments that control spin state and redox potential. Pendant groups are strategically placed to provide water solubility without interfering with the iron coordination sphere.
3Measurement precision
If Fe(III) complexes are designed for T1 relaxivity, then MRI contrast effectiveness is improved, but device complexity increases due to macrocyclic ligand requirements
Solution Approach 1:
The macrocyclic ligand structure serves multiple functions simultaneously: it controls iron's oxidation state, maintains high-spin configuration for T1 relaxivity, provides water solubility through pendant groups, and prevents ROS generation by tuning redox potential. This multi-functional design achieves T1 contrast effectiveness without excessive complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The Fe(III) macrocyclic complexes provide effective T1 and T2 MRI contrast agents with improved safety and efficacy, offering stable, water-soluble alternatives to gadolinium-based agents.
Implementation Method 1
High-spin Fe(III) has favorable paramagnetic properties that can shorten T1 relaxation times of the protons of water for MRI contrast
Data Source
AI summary
Provided are macrocyclic compounds and compounds with two or more macrocyclic groups, iron coordinated macrocyclic compounds, and iron coordinated compounds with two or more macrocyclic groups. The iron is high-spin iron(III). The iron coordinated compounds may exhibit a negative redox potential (e.g., relative to a normal hydrogen electrode at a biologically relevant pH, for example, a pH of 6.5-7.5). The compounds can be used as MRI contrast agents.