pH-Sensitive Polymeric Compositions for Unique Relaxation Time Sensing
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Solution Overview
Problem
pH-sensitive hydrogels like p-HEMA-BIS suffer from ambiguity in pH detection due to multiple pH values corresponding to a single relaxation time, making it difficult to accurately determine pH within preferred detection ranges.
Innovation Solution
Development of polymeric compositions comprising a crosslinked co-polymer with a cationic monomer, an anionic monomer, and a crosslinker, where the molecular ratio of cationic to anionic monomers is optimized to ensure a unique relaxation time at each pH within a range of 4.5 to 8, allowing for precise pH sensing by measuring relaxation times and comparing them to a standard curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If p-HEMA-BIS hydrogels are used for pH sensing, then the relaxation time can depend on pH, but a single relaxation time corresponds to multiple pH values causing ambiguity
Solution Approach 1:
The patent changes the chemical composition parameters of the hydrogel by incorporating both cationic monomers (e.g., DMAEMA, DABCO) and anionic monomers (e.g., acrylic acid, itaconic acid) in specific molar ratios. This compositional parameter change modifies the pH-response characteristics of the hydrogel, creating a monotonic relaxation time vs. pH relationship that eliminates the ambiguity present in conventional p-HEMA-BIS hydrogels.
Solution Approach 2:
The patent creates a composite hydrogel system by combining multiple types of monomers with opposite charge characteristics (cationic and anionic) within the same polymer network. This composite approach allows the material to exhibit enhanced and tunable pH sensitivity with a monotonic response curve, resolving the information loss problem while maintaining measurement precision.
2Adaptability or versatility
If the relaxation time peaks at pH 6.5 to cover preferred detection ranges, then detection range is improved, but ambiguity increases as off-peak values map to multiple pH levels
Solution Approach 1:
Instead of accepting the conventional peaked response curve where multiple pH values map to the same relaxation time, the patent inverts the approach by designing a system where the response is monotonic across the detection range. This inversion of the response characteristic ensures that each relaxation time value corresponds to exactly one pH value, eliminating ambiguity while maintaining broad detection range coverage.
3Measurement precision
If a crosslinked co-polymer with cationic and anionic monomers is used, then unique relaxation time at each pH is achieved, but device complexity increases
Solution Approach 1:
The patent merges multiple functional monomers (cationic and anionic) into a single crosslinked co-polymer network. By combining these components during polymerization, the complex pH-responsive behavior is achieved within one integrated material system rather than requiring separate components, thus managing complexity while maintaining high measurement precision.
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 polymeric compositions provide a unique relaxation time at each pH within the specified range, enabling accurate pH determination in biological tissues and liquids, reducing ambiguity and improving detection accuracy.
Implementation Method 1
pH-sensitive hydrogels are known, such as those that include poly-hydroxyethylmethacrylate (p-HEMA) crosslinked with N,N′-methylenebisacrylamide (BIS). p-HEMA-BIS hydrogels have been used as sensors, because the transverse relaxation time (T2) of the p-HEMA-BIS hydrogels can depend on the pH of the environments in which the hydrogels are disposed.
Data Source
AI summary
Provided herein are polymeric compositions having a relaxation time that is a function of pH. The polymeric compositions can include an anionic monomer, a cationic monomer, and a crosslinker. The crosslinker may comprise at least one of a diacrylate crosslinker and a dimethacrylate crosslinker. Also provided herein are methods of pH sensing, and methods of forming a polymeric composition. Kits of parts also are provided that include a polymeric composition. The polymeric compositions may be used to determine the pH of one or more biological tissues and/or liquids.