Multimeric MRI Contrast Agents via Cleavable Linkers
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Solution Overview
Problem
Current superparamagnetic iron oxide particles (SPIOs) for MRI contrast agents face challenges in accurately targeting specific regions due to size-related issues, with small particles being quickly cleared and large particles causing microvessel occlusion, leading to reduced image quality and potential pathology.
Innovation Solution
Development of multimeric particles composed of smaller metal-containing particles covalently bonded by cleavable linker groups, allowing for controlled breakdown and biodegradability, which initially provides a high signal-to-noise ratio and then degrades to prevent occlusion and improve safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If small particles (50 nm to 200 nm) are used as contrast agents, then a strong magnetic resonance signal is provided, but the particles are quickly cleared from the site of interest and linger in the blood, reducing image quality due to low signal to background noise ratio
Solution Approach 1:
The contrast agent is designed as a multimeric particle consisting of multiple smaller metal-containing particles (50-200 nm) covalently bonded together through linker groups. This segmentation allows each subunit to maintain strong magnetic resonance signal properties while the aggregated multimeric structure provides improved signal to noise ratio and controlled clearance characteristics.
2Quantity of substance
If large particles (around 1 μm) are used as contrast agents, then a much better signal to noise ratio is provided, but the particles can cause microvessel occlusion leading to lower clearance rate and potential iatrogenic pathology
Solution Approach 1:
The multimeric particle incorporates cleavable linker groups that can be broken down in vivo through enzymatic or other biological processes. This dynamic design allows the particle to initially exist as a large multimeric structure providing high signal to noise ratio, then progressively degrade into smaller subunits that can be safely cleared from the body, preventing microvessel occlusion and improving clearance rate.
3Object-affected harmful factors
If particles are made biodegradable to prevent occlusion and improve safety, then clearance rate is improved, but the dwell time may be reduced before imaging can be performed
Solution Approach 1:
The multimeric particle is designed with cleavable linker groups that remain stable during storage and initial circulation, allowing the particle to maintain its large multimeric structure during the imaging window. The degradation is triggered or accelerated after the imaging procedure is complete, ensuring that the particle provides its imaging function at full strength before breaking down into smaller clearable units.
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 multimeric particles offer a balance of signal quality and safety by providing a high signal-to-noise ratio initially and degrading over time, reducing the risk of occlusion and improving image contrast while ensuring safe clearance.
Implementation Method 1
at least some of the linker groups are enzymatically cleavable or otherwise capable of being broken down in vivo
Implementation Method 2
linker groups which are cleavable
Implementation Method 3
The superparamagnetic behaviour of mixed iron oxides (e.g. magnetite, Fe2O3/Fe3O4) results in magnetization when placed in a magnetic field such as is found in an MRI apparatus
Data Source
AI summary
The invention provides multimeric particle comprising metal-containing particles covalently bonded to one another by linker groups wherein at least some of said linker groups are cleavable. The invention further provides a contrast agent comprising said multimeric particles, along with a method of improving contrast of an image using said contrast agent.