Zwitterionic Polysiloxane for Blood-Contacting Devices
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Solution Overview
Problem
Polydimethylsiloxane (PDMS) compositions used in medical devices suffer from nonspecific adsorption of proteins and platelet deposition when in contact with blood, due to their hydrophobic nature, which complicates their hemocompatibility and stability.
Innovation Solution
A zwitterionic polysiloxane polymer composition is introduced, comprising a poly(dialkylsiloxane) block and a zwitterionic moiety, formed through methods such as copolymerization of poly(dialkylsiloxane) diol, diisocyanate, and tertiary amine alkyl diol, followed by reaction with a substituted saturated heterocylic compound to introduce zwitterionic groups, enhancing the hydrophilicity and reducing protein and platelet adsorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDMS is used for medical devices, then stability and low cytotoxicity are improved, but nonspecific adsorption of proteins and platelet deposition occurs
Solution Approach 1:
The patent changes the surface chemical parameters of PDMS by introducing zwitterionic groups through reaction with substituted saturated heterocyclic compounds. This transforms the hydrophobic surface into a hydrophilic zwitterionic surface, fundamentally altering the surface energy and chemical composition to prevent protein and platelet adsorption while preserving the bulk stability of PDMS
Solution Approach 2:
The patent creates a composite surface structure where zwitterionic moieties are grafted onto the PDMS backbone. This forms a hybrid material system combining the mechanical stability of PDMS with the antifouling properties of zwitterionic groups, achieving both reliability and resistance to harmful adsorption effects
2Reliability
If surface modification is applied to improve hemocompatibility, then blood-compatibility is improved, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary surface modification by pre-synthesizing zwitterionic-functionalized PDMS polymers before device fabrication. The zwitterionic groups are introduced during the polymerization or curing process, so the material arrives at the manufacturing stage already equipped with hemocompatible surface properties, eliminating the need for complex post-processing modification steps
Solution Approach 2:
The patent extracts the complex multi-step surface modification procedures from the manufacturing process. By incorporating zwitterionic functionality directly into the polymer synthesis, the harmful adsorption problem is solved at the material level rather than requiring separate surface treatment steps, thereby simplifying the overall manufacturing workflow
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 polysiloxane composition significantly reduces protein and platelet deposition, improves hemocompatibility, and maintains stability against enzymatic and oxidative stress, making it suitable for blood-contacting medical devices.
Implementation Method 1
enhancing the hydrophilicity and reducing protein and platelet adsorption
Implementation Method 2
zwitterionic group... reduces protein and platelet deposition
Implementation Method 3
maintains stability against enzymatic and oxidative stress
Data Source
AI summary
A zwitterionic polysiloxane polymer (e.g., a polyurethane elastomer) composition having poly(dialkylsiloxane) blocks and a zwitterionic moiety is prepared by the copolymerization of a poly(dialkylsiloxane) diol, a diisocyanate, a tertiary amine alkyl diol, and a poly(dialkylsiloxane) diamine to form a poly(urethane urea) copolymer. A substituted saturated heterocylic compound is reacted with the tertiary amine of the poly(urethane urea) copolymer to introduce a zwitterionic group into the poly(urethane urea) copolymer backbone. A polysiloxane polymer having a zwitterionic moiety is prepared by reacting a diallyl tertiary amine compound and a substituted saturated heterocylic compound to form a diallyl zwitterionic macromer and cross-linking a vinyl terminated poly(dialkylsiloxane) and the diallyl zwitterionic macromer with a curing agent to introduce a zwitterionic group into the poly(dialkylsiloxane) polymer.