Scaffold Protein Contrast Agents for MRI Relaxivity and Circulation
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Solution Overview
Problem
Current MRI contrast agents, such as those based on gadolinium ions, have limited relaxivity and short circulation times, making it challenging to achieve sufficient image contrast and prolonged imaging windows, especially for visualizing tumors and diseases.
Innovation Solution
Development of novel contrast agents comprising a scaffold protein with tailored metal ion binding sites, specifically designed to integrate paramagnetic and heavy metal ions, enhancing relaxivity and circulation time by optimizing rotational correlation times and water exchange rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gadolinium-based contrast agents are used, then image contrast is enhanced, but circulation time is short and relaxivity is limited
Solution Approach 1:
The patent combines gadolinium ions with large molecular weight polymers (dendrimers, copolymers, or proteins) to create composite contrast agents. The polymer scaffold provides prolonged circulation time while the integrated metal ion binding sites maintain high relaxivity, resolving the contradiction between short circulation time and need for enhanced contrast.
Solution Approach 2:
The patent merges the contrast-enhancing function of gadolinium ions with the circulation-prolonging properties of macromolecular scaffolds. By covalently or non-covalently linking multiple metal ion binding sites to the polymer structure, the agent achieves both enhanced relaxivity and extended circulation time.
2Measurement precision
If high concentration of gadolinium is used, then sufficient contrast is achieved, but toxicity increases
Solution Approach 1:
The patent uses polymer-gadolinium composite structures where the polymer scaffold reduces the required concentration of gadolinium ions. The macromolecular structure provides multiple binding sites that collectively enhance contrast while the polymer framework reduces toxicity by controlling metal ion release and improving pharmacokinetics.
Solution Approach 2:
The patent changes the molecular weight and structural parameters of the contrast agent by using macromolecular scaffolds. This increases the hydrodynamic radius and alters biodistribution, allowing lower gadolinium concentrations to achieve sufficient contrast while reducing toxicity through improved clearance and stability.
3Duration of action of moving object
If macromolecules are used to prolong circulation, then circulation time increases, but relaxivity decreases
Solution Approach 1:
The patent integrates multiple metal ion binding sites within the macromolecular structure to compensate for the reduced relaxivity per unit mass. By clustering multiple gadolinium binding sites on the polymer scaffold, the overall relaxivity is enhanced while maintaining the circulation-prolonging benefits of the macromolecular structure.
Solution Approach 2:
The patent divides the contrast agent into modular units with metal ion binding sites distributed throughout the polymer structure. This segmentation allows multiple independent binding sites to contribute to overall relaxivity while the polymer backbone maintains circulation time, resolving the trade-off between size and relaxivity.
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 novel contrast agents provide improved image contrast and prolonged imaging windows, reducing toxicity and increasing sensitivity, allowing for more effective visualization of tissues and tumors with enhanced relaxivity and specificity.
Implementation Method 1
at least one tailored metal ion binding site capable of chelating paramagnetic and heavy metal ions
Implementation Method 2
enhancing relaxivity and circulation time by optimizing rotational correlation times and water exchange rates
Data Source
Figure 1A~1E
Figure 2
Figure 3A
AI summary
Contrast agents comprising a scaffold protein having at least one operative integrated metal ion binding site.