Targeted Contrast Agents for MRI Specificity
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Solution Overview
Problem
Current MRI contrast agents lack specificity for targeting specific cells and tissues, leading to non-selective accumulation and reduced efficacy in visualizing early tumor lesions and metastases, with existing agents having low relaxivity and short circulation times.
Innovation Solution
Development of targeted contrast agents comprising a peptide or protein moiety linked to a contrast protein with metal ion binding sites, allowing for specific accumulation in targeted cells through receptor-mediated endocytosis, reducing exposure to normal cells and enhancing image contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MRI contrast agents are used, then image contrast can be achieved, but the agents lack specificity for targeting specific cells and tissues leading to non-selective accumulation
Solution Approach 1:
The patent combines a contrast agent core with a targeting moiety (peptide, protein, or small molecule) to create a hybrid molecule that simultaneously provides image contrast and cell-specific targeting capability. This merging resolves the contradiction by integrating both functions into a single agent that can selectively accumulate in target cells while maintaining contrast enhancement properties
Solution Approach 2:
The contrast agent is designed as a composite structure consisting of a contrast-generating component (such as gadolinium chelate) and a targeting component (such as a peptide or antibody fragment). This composite approach allows the agent to exhibit both contrast enhancement and selective cellular targeting, addressing the limitation of conventional non-specific agents
2Measurement precision
If high concentration of contrast agent is administered to achieve sufficient contrast, then image quality improves, but the circulation time becomes very short limiting the data collection window
Solution Approach 1:
The targeting moiety directs the contrast agent to accumulate locally at the target cell surface or interior, creating a high local concentration at the site of interest. This local concentration effect allows for sufficient image contrast with lower systemic doses, thereby extending the effective circulation time window for imaging
Solution Approach 2:
The contrast agent is designed to bind to and accumulate on target cells before imaging begins, allowing the agent to be retained at the target site during the imaging process. This preliminary accumulation ensures sufficient contrast signal is established within the available circulation time window
3Adaptability or versatility
If contrast agents are administered systemically, then they can reach target cells, but exposure to normal cells increases causing potential toxicity
Solution Approach 1:
The targeting moiety acts as an intermediary that guides the contrast agent specifically to target cells expressing the corresponding receptor. This mediator function ensures that systemic administration results in selective accumulation at the target site rather than uniform distribution, reducing exposure and potential toxicity to normal cells
Solution Approach 2:
The patent utilizes the natural process of receptor-mediated endocytosis, which cells use to internalize substances, to deliver the contrast agent specifically to target cells. By harnessing this biological mechanism, the agent achieves efficient cellular uptake in target cells while minimizing interaction with and potential toxicity to normal cells that lack the specific receptor
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 targeted contrast agents provide improved image contrast and reduced toxicity by selectively accumulating in specific cells, enhancing MR image quality and safety by minimizing exposure to normal cells.
Implementation Method 1
a contrast protein that is preferably a contrast agent and can be an organic polymer such as a protein having at least one metal ion binding site capable of chelating paramagnetic and heavy metal ions
Implementation Method 2
allowing for specific accumulation in targeted cells through receptor-mediated endocytosis
Data Source
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AI summary
A contrast agent having a contrast protein have contrast properties and at least one targeting moiety, wherein the at least one targeting moiety is operatively linked to or incorporated within the contrast protein. Methods for targeting contrast agents and for preparing such agents are included.