HBED-Based Bifunctional Chelate for Stable MRI Contrast Agents
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Solution Overview
Problem
Current metal chelates used in magnetic resonance imaging (MRI) face challenges such as toxicity of free metal ions, instability, rapid clearance from the body, and insufficient image quality, particularly with existing bifunctional chelates like EDTA and deferoxamine, which are either redox active or have hydrolytically sensitive conjugations.
Innovation Solution
Development of a contrast agent composition featuring a metal-complex with a bifunctional chelating agent based on the hydroxy bis ethylene diamine dicarboxylate (HBED) framework, incorporating polyethylene glycol (PEG) moieties to enhance stability, distribution, and relaxivity, allowing for improved imaging at lower doses and increased patient safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing bifunctional chelates like EDTA and deferoxamine are used, then the agent can bind to metal and provide contrast enhancement, but the chelates are either redox active (safety concern) or have hydrolytically sensitive conjugations (instability)
Solution Approach 1:
The patent modifies the chelate structure by changing the chemical parameters of the conjugation chemistry. Instead of using traditional isocyanate or isothiocyanate linkages that are hydrolytically sensitive, the invention employs novel stable linkages such as amide bonds, triazole rings, or other hydrolytically stable connectors that resist degradation in physiological conditions, thereby improving reliability while eliminating harmful redox activity and hydrolytic sensitivity.
Solution Approach 2:
The invention creates a composite chelate structure that combines multiple functional components: a metal-binding chelating agent, a stable linker chemistry, and a targeting or imaging moiety. This composite approach integrates the benefits of each component while mitigating their individual weaknesses, resulting in a bifunctional chelate that is both stable and non-redox active.
2Measurement precision
If the agent size is increased or disease-related biomarker targeting is incorporated, then selective localization at diseased tissue is improved, but the device complexity increases
Solution Approach 1:
The bifunctional chelate is segmented into distinct functional modules: a metal-chelating core, a stable linker, and a targeting moiety (such as a peptide, antibody fragment, or small molecule that binds to disease-related biomarkers). This modular segmentation allows each component to be optimized independently while maintaining overall functionality, improving selective localization without excessive complexity.
Solution Approach 2:
The chelate design incorporates universal building blocks that can be adapted for different imaging applications and targeting purposes. The stable linker and chelating core serve multiple functions (metal binding, stability, contrast enhancement), while the targeting moiety can be swapped to target different biomarkers, reducing overall complexity through reuse of proven components.
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 bifunctional metal-chelate complexes demonstrate enhanced stability, prolonged vascular residence, improved tumor selectivity, and increased relaxivity, enabling higher-quality MRI images at lower dosages with reduced toxicity and improved patient tolerance.
Implementation Method 1
a bifunctional chelate, which binds to the metal as well as to a second moiety
Implementation Method 2
The MR contrast enhancement agents improves both the quality of images obtained in an MR imaging procedure
Data Source
AI summary
A contrast agent composition and a method of diagnostic imaging are provided. The composition comprises a pharmaceutically acceptable carrier and a metal-complex comprising a ligand having structure (XXX):wherein R1, R2, R3, R7, R8, R′1, R′2, R′3, R7′ and R8′ are selected form hydrogen, a protected C1-C3 hydroxyalkyl group, or a C1-C3 alkyl group; R4, R′4 are selected from a hydrogen, a hydroxyl, a protected hydroxyl group, a protected C1-C3 hydroxyalkyl group, a C1-C3 alkyl group; n is an integer between 0 and 4; R5, R′5 are selected from a hydrogen, a protecting group comprising C1-C30 aliphatic radicals, C3-C30 cycloaliphatic radicals, C2-C30 aromatic radicals, m is an integer between 1 and 10; at least one of R7 and R′7 is acidic groups or protected acidic groups; Y comprises a protein or peptide moiety, a particle, a micelle, a liposome, an organic molecule, oligomer, polymer or a hydrophilic moiety.