Zwitterionic Polymer Composition for Protein Resistance Across Acidic pH
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Solution Overview
Problem
Existing polymers derived from 2-Methacryloyloxyethyl phosphorylcholine (MPC) monomers exhibit reduced protein adsorption inhibitory effect at lower pH levels, and there is a need for materials with improved stability and efficacy across a broader pH range, including acidic conditions.
Innovation Solution
A zwitterionic compound is developed with a monomer structure where the quaternary ammonium cation group and phosphodiester group are interchanged, resulting in polymers with enhanced hydrophilicity and protein adsorption inhibition, even at acidic pH levels, by incorporating specific monomer units and ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymers are obtained by polymerization of MPC monomer, then protein adsorption inhibitory effect is achieved, but the effect decreases at lower pH levels
Solution Approach 1:
The invention changes the chemical structure parameter of the monomer by replacing the phosphodiester group with a carboxylate group, transforming the zwitterionic structure from having a permanent positive charge (quaternary ammonium) and negative charge (phosphodiester) to having a permanent positive charge (quaternary ammonium) and a pH-dependent negative charge (carboxylate). This parameter change enables the polymer to maintain its protein adsorption inhibitory effect across a broader pH range, particularly in acidic conditions where the carboxylate group remains ionized.
Solution Approach 2:
The invention creates a composite monomer structure combining a quaternary ammonium cation group with a carboxylate anion group, forming a new type of zwitterionic monomer. This composite structure integrates the benefits of both permanent charges and pH-responsive charges, resulting in a polymer that maintains excellent protein adsorption inhibition across varying pH conditions, unlike the original MPC polymer whose phosphodiester group provides less pH stability.
2Reliability
If PEG chains are used to suppress protein adsorption, then protein adsorption inhibitory effect is achieved, but the material is easily degraded by oxidation
Solution Approach 1:
The invention replaces the oxidation-sensitive PEG chains with zwitterionic polymer chains containing quaternary ammonium and carboxylate groups. These zwitterionic structures are inherently more resistant to oxidation degradation while maintaining the desired protein adsorption inhibitory effect, thus providing a more stable long-term solution for biomedical applications.
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 zwitterionic compound demonstrates excellent protein adsorption inhibition over a wide pH range, including acidic conditions, and maintains stability in harsh environments.
Implementation Method 1
Materials with a surface onto which water-soluble PEG chains are grafted can suppress protein adsorption on the surface by repelling approaching proteins with hydrated PEG chains
Implementation Method 2
When the material surface is electrically neutral, electrostatic interactions between a protein and the interface is suppressed
Implementation Method 3
on a hydrophilic surface, the interfacial free energy is low, and protein adsorption is thus suppressed
Implementation Method 4
Polymers obtained by polymerization of MPC as a monomer have the four characteristics described above due to a zwitterionic group
Data Source
AI summary
An object is to provide a zwitterionic compound having an excellent protein adsorption inhibitory effect. The zwitterionic compound is a polymer comprising a unit represented by the following formula (1):wherein R1 is a hydrogen atom or a methyl group, R2 is OH or O−, X1 is —O— or —N(Q1)-, Q1 is a hydrogen atom or a C1-6 alkyl group, m is an integer of 1 to 12, and n is an integer of 1 to 4.