Aza Metal Complexes for MRI Contrast Agents
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Solution Overview
Problem
Conventional gadolinium complexes used as MRI contrast agents do not adequately utilize the T1-reducing effect of gadolinium ions due to insufficient coordination, leading to reduced image contrast.
Innovation Solution
A metal complex is developed with a cyclic structure that coordinates gadolinium ions more effectively, utilizing a compound represented by Formula (A) with specific side chains and repeating units to enhance T1-reducing ability, resulting in an improved MRI contrast agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gadolinium complex is formed with 7 or 8 coordinating functional groups (conventional ligand structure), then the complex is stable and safe for use, but the T1-reducing ability is insufficient due to inadequate coordination geometry
Solution Approach 1:
The patent changes the coordination geometry parameter from conventional 7- or 8-coordinate structures to a 9-coordinate geometry by designing ligands with specific macrocyclic structures and pendant arms that provide exactly 9 coordination sites for the gadolinium ion, thereby optimizing the T1-reducing ability while maintaining complex stability
Solution Approach 2:
The patent creates a composite coordination structure combining a macrocyclic ligand framework with additional pendant coordinating groups, forming a hybrid ligand system that provides both the stability of macrocyclic chelation and the enhanced T1 effect of 9-coordinate geometry
2Ease of manufacture
If Gd3+ is coordinated in a nine-coordination geometry, then the T1-reducing ability is maximized, but the ligand structure becomes more complex
Solution Approach 1:
The patent divides the ligand into functional segments: a macrocyclic core structure that provides 4-5 coordination sites, and pendant arms that provide additional 4-5 coordination sites, totaling 9 coordination sites. This segmentation allows systematic design of the 9-coordinate geometry while managing structural complexity
Solution Approach 2:
The patent designs the macrocyclic ligand framework to serve multiple functions: providing coordination sites for gadolinium, ensuring complex stability, and enabling the 9-coordinate geometry. The same macrocyclic core can be modified with different pendant arms to achieve various 9-coordinate configurations
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 new metal complex demonstrates superior T1-reducing effects compared to conventional agents, enhancing image contrast and stability, as evidenced by increased T1 relaxation times and improved MRI image quality.
Implementation Method 1
a complex (hereinafter referred to as a 'gadolinium complex'), which is stabilized by coordinating an organic ligand to a gadolinium ion
Implementation Method 2
Magnetic resonance imaging (MRI) is a method for obtaining an image of a tissue or structure or the like in the living body using nuclear magnetic resonance in a magnetic field
Data Source
AI summary
A core of a cyclic structure represented by (—N—(CH2)n—)k is bonded to a dendrimer-type side chain with a specific branched structure at all nitrogen atoms in the core to produce a compound with a specific structure for producing a metal complex that exhibits a T1-reducing effect, and the resulting compound is coordinated to a metal ion that has a T1-reducing effect to obtain a metal complex that exhibits an excellent T1-reducing effect which is useful as an effective component of an MRI contrast agent and an MRI contrast agent using the same.