Ion-Selective Membrane Solvents for Protein-Resistant Chloride Sensing
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Solution Overview
Problem
Existing ion-selective membranes for chloride ions, particularly those using metal porphyrin complexes and o-nitrophenyl octyl ether (NPOE) as membrane solvents, exhibit decreased electromotive force response when immersed in aqueous solutions containing protein, due to an unclear interface between the hydrophobic membrane and aqueous solution caused by the surfactant function of proteins.
Innovation Solution
The use of a membrane solvent with a compound represented by a specific general formula (CLogP≥9) that strengthens intermolecular hydrophobic interactions and increases intramolecular hydrophobic groups, such as alkyl ester groups, to form a hydrophobic membrane that inhibits the surfactant function of proteins, thereby maintaining electromotive force response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal porphyrin complex and NPOE are used in the ion-selective membrane, then chloride ion selectivity is improved, but the electromotive force response decreases when immersed in protein-containing solutions
Solution Approach 1:
The patent changes the membrane solvent from NPOE to compounds with CLogP≥9 (such as DOIP, DOTP, or TOP), which fundamentally alters the hydrophobicity parameter of the membrane. This parameter change prevents protein adsorption while maintaining chloride ion selectivity, thereby resolving the contradiction between ion selectivity and reliability in protein-containing solutions.
Solution Approach 2:
The patent creates a composite membrane system by combining metal porphyrin complex (ionophore) with specific high CLogP membrane solvents and polymer matrices. This composite structure maintains the ion-selective functionality while the high CLogP solvent component provides protein resistance, simultaneously achieving both chloride ion selectivity and reliable electromotive force response.
2Measurement precision
If the membrane interface between hydrophobic membrane and aqueous solution is formed, then ion selectivity is achieved, but protein adsorption occurs causing response decrease
Solution Approach 1:
The patent converts the harmful surfactant function of proteins into a beneficial effect by using high CLogP membrane solvents that are so hydrophobic they prevent protein adsorption entirely. The extreme hydrophobicity, which could be considered excessive, actually becomes the protective mechanism that eliminates the harmful protein-membrane interaction while preserving the necessary hydrophobic membrane interface for ion selectivity.
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 proposed membrane solvent composition maintains a sensitivity ratio of 0.6 or more, preferably 0.8 or more, for chloride ion concentration measurements in protein-containing solutions, ensuring high durability and accuracy of ion-selective electrodes.
Implementation Method 1
a membrane solvent satisfying CLogP≥9 and including a compound represented by general formula (1)... strengthens intermolecular hydrophobic interactions... to form a hydrophobic membrane
Implementation Method 2
an ion-selective substance called an ionophore is trapped in a matrix... a potential difference corresponding to the activity of a target ion occurs at an interface between an ion-selective membrane and the solution
Data Source
AI summary
An ion-selective membrane of an embodiment includes a metal porphyrin compound, a polymer, and a membrane solvent. The membrane solvent is a compound that satisfies CLogP≥9. The compound has a benzene ring. The first position of the benzene ring is an alkyl ester group having 5 or more and 19 or less carbon atoms which may have a substituent. At least one of the third, fourth, and fifth positions of the benzene ring is an alkyl ester group having 5 or more and 19 or less carbon atoms which may have the substituent.