Polyurethane Heart Valve Leaflets With Narrow Molecular Weight Control
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Solution Overview
Problem
Current heart valve replacements, whether mechanical or bioprosthetic, fail to meet durability and biocompatibility requirements, necessitating lifelong anticoagulation or suffering from oxidative degradation and calcification, while polymeric alternatives have poor mechanical properties and variable molecular weight distributions.
Innovation Solution
Development of a two-step process to create a linear polyurethane or polyurethane-urea polymer with a hydrogen-bonded, phase-separated structure, using specific chain extenders like benzene 1,4-diol, to produce a polymer with narrow molecular weight distribution and improved mechanical properties, eliminating the need for reinforcement and melt processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If mechanical valves are used, then durability is improved, but biocompatibility deteriorates requiring lifelong anticoagulation
Solution Approach 1:
The patent changes the material parameters from traditional mechanical materials (pyrolytic carbon, titanium alloy) to a specific polyurethane polymer composition with controlled molecular weight distribution and hydrogen bonding characteristics, achieving both durability and biocompatibility simultaneously
Solution Approach 2:
The patent creates a composite polyurethane material combining hard segments (isocyanate-chain extender) and soft segments (polyol) in a phase-separated structure, achieving properties that neither component alone could provide - both mechanical durability and blood compatibility
2Object-affected harmful factors
If bioprosthetic tissue valves are used, then biocompatibility is improved, but durability deteriorates due to oxidative degradation and calcification
Solution Approach 1:
The patent changes the chemical composition parameters by selecting specific polyols (poly(tetramethylene oxide), poly(ethylene oxide)) and chain extenders that resist oxidative degradation and calcification, while maintaining biocompatibility through controlled molecular structure and hydrogen bonding
Solution Approach 2:
The patent replaces expensive xenogenic biological tissues (porcine valves, bovine pericardium) with synthetic polyurethane polymers that can be manufactured consistently and are not limited by geographical availability or disease
3Object-affected harmful factors
If polymeric heart valve materials are used, then biocompatibility is improved, but mechanical properties deteriorate requiring reinforcement
Solution Approach 1:
The patent creates a composite polyurethane structure with hard segments (isocyanate-chain extender) providing mechanical strength and soft segments (polyol) providing elasticity and biocompatibility, eliminating the need for reinforcement while maintaining both properties
Solution Approach 2:
The patent optimizes the molecular weight distribution parameters and hydrogen bonding density to achieve sufficient mechanical strength without reinforcement, while maintaining biocompatibility through controlled polymer architecture
4Ease of manufacture
If polymers with large molecular weight distribution are used, then ease of manufacture is improved, but mechanical properties and biocompatibility deteriorate
Solution Approach 1:
The patent changes the molecular weight distribution parameter to narrow (polydispersity index 1.0-1.2) which improves mechanical properties and biocompatibility, while adjusting the polymer architecture to maintain manufacturability through controlled polymerization processes
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 resulting polymer exhibits excellent fatigue resistance, biocompatibility, and mechanical properties, suitable for heart valve leaflets, capable of withstanding millions of cycles without plastic deformation and integrating seamlessly with the native environment.
Implementation Method 1
reacting the prepolymer with one or more chain extender molecules to form a linear polyurethane or polyurethane-urea polymer
Implementation Method 2
The resulting polymer exhibits a hydrogen-bonded, phase-separated structure
Implementation Method 3
The resulting polymer exhibits a hydrogen-bonded, phase-separated structure
Implementation Method 4
capable of withstanding millions of cycles without plastic deformation
Data Source
AI summary
A method of forming an implantable biomaterial comprising the steps of providing a polyether-diisocyanate prepolymer, reacting the prepolymer with one or more chain extender molecules typically including benzene 1,4-diol to form a mouldable polymer selected from a polyurethane or polyurethane-urea polymer or a polyurethane-urea block copolymer; placing the mouldable polymer into an implantable biomaterial shaped mould, and shaping and curing the mouldable polymer in the implantable biomaterial shaped mould to form the implantable biomaterial. An implantable biomaterial such as a heart valve leaflet is also disclosed.