Fluorinated PEG Copolymers for MRI Contrast Agents
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Solution Overview
Problem
Current 19F-based MRI contrast agents face challenges with limited solubility in aqueous liquids, leading to aggregation and toxicity issues, which affect their efficacy and safety for biological applications.
Innovation Solution
Development of fluorine-rich polymers with a specific macromolecular architecture that incorporates polyethylene glycol (PEG) blocks and fluorinated moieties, allowing for high affinity to water and tunable relaxation times, enhancing signal-to-noise ratios and solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluorine-rich contrast agents are used to enhance MRI signal intensity, then signal-to-noise ratio is improved, but solubility in aqueous liquids deteriorates leading to aggregation
Solution Approach 1:
The contrast agent is segmented into distinct functional blocks: hydrophobic fluorinated moieties (perfluoroalkyl groups) provide high MRI signal intensity, while hydrophilic polyethylene glycol (PEG) blocks provide water solubility. This segmentation allows each component to perform its specialized function without compromising the other, resolving the contradiction between signal enhancement and solubility.
Solution Approach 2:
The invention creates a composite polymer structure combining fluorinated hydrocarbon blocks (CF3-(CF2)n-CF3) with polyethylene glycol blocks. This composite material integrates the high gyromagnetic ratio and natural abundance of 19F nuclei for MRI detection with the excellent water solubility of PEG, simultaneously achieving both high signal-to-noise ratio and reliable aqueous solubility.
2Measurement precision
If fluorine-rich contrast agents are used to improve imaging signal, then signal intensity is enhanced, but aggregation occurs reducing efficacy
Solution Approach 1:
By segmenting the polymer into alternating hydrophobic fluorinated blocks and hydrophilic PEG blocks, the structure prevents aggregation of fluorinated moieties while maintaining high local concentration for MRI signal. The hydrophilic PEG segments act as spacers that keep fluorinated blocks separated in aqueous environment, preventing aggregation while preserving signal intensity.
Solution Approach 2:
The invention optimizes parameters including the length of fluorinated blocks (n=2-10), the length of PEG blocks (m=2-20), and the ratio of fluorinated to PEG blocks (x:y) to balance hydrophobic and hydrophilic interactions. These parameter adjustments ensure the polymer remains soluble and monodisperse while maintaining high fluorine content for MRI detection.
3Measurement precision
If fluorinated contrast agents are administered to increase contrast, then image contrast is enhanced, but toxicity to tissue and organs increases
Solution Approach 1:
The composite polymer structure combines fluorinated moieties for contrast enhancement with biocompatible PEG blocks that provide colloidal stability and reduce toxicity. The PEG corona prevents non-specific protein adsorption and immune recognition, reducing toxicity while the fluorinated core provides the necessary contrast signal.
Solution Approach 2:
The invention optimizes the molecular weight, block length ratios, and fluorine content parameters to achieve effective contrast at lower doses. By tuning these parameters, the contrast agent provides sufficient image contrast while minimizing the total amount administered, thereby reducing potential toxicity to tissue and organs.
4Loss of information
If pre- and post-injection imaging is performed to evaluate contrast agent performance, then diagnostic information is obtained, but scan time increases
Solution Approach 1:
The polymer architecture parameters (block lengths, ratios) are optimized to achieve maximum contrast enhancement that is detectable with minimal imaging time. The high signal-to-noise ratio provided by the fluorinated PEG copolymers allows for rapid single-shot imaging sequences, reducing the need for extended pre- and post-injection imaging protocols while still providing sufficient diagnostic information.
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 polymers exhibit improved solubility and relaxation properties, providing enhanced imaging capabilities with increased signal intensity and reduced aggregation, making them suitable for biomedical applications.
Implementation Method 1
19F nuclei can exhibit high gyromagnetic ratio (comparable to that of protons), yielding pronounced NMR signal
Implementation Method 2
C—F bonds involve π-πF-interactions they exhibit high enthalpy, which can impart them with a stabilizing energy up to ~25 kJ/mol
Implementation Method 3
1H-based MRI generally relies on changes in the transverse (T2) and longitudinal (T1) spin relaxation properties of water protons distributed in living tissues
Data Source
AI summary
Contrast agents, compositions including contrast agents, methods of forming contrast agents, and methods of imaging. Contrast agents may have a desirable solubility in liquids, such as aqueous liquids. Methods of forming contrast agents may include contacting a polymer that includes anhydride functional groups with one or more compounds. Methods of imaging may include administering to patients a contrast agent or composition including a contrast agent.