Injectable PVA Hydrogel Cross-Linking for Nucleus Pulposus Repair
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current cross-linked hydrogels for nucleus pulposus replacement have limitations such as low modulus, non-injectable forms, and susceptibility to degradation, which affect their mechanical properties and stability in the body.
Innovation Solution
A chemically cross-linked hydrogel composition comprising poly(vinyl alcohol) (PVA) with a second polymer selected from polyhydric alcohol, polyvalent epoxy, polyvalent amine, dialdehyde, or diisocyanate compounds, allowing the hydrogel to be flowable above its melting point and solidifying at physiological temperatures, enabling injectable and stable tissue repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If physical cross-linking is used in PVA hydrogels, then the hydrogel can be injected, but the mechanical properties degrade over time due to melting out of crystallites
Solution Approach 1:
The patent changes the cross-linking mechanism from physical to chemical, fundamentally altering the bonding parameters to achieve both injectability and long-term stability. The chemical cross-links maintain mechanical properties by preventing crystallite melting while allowing injection through controlled degradation or phase transition.
Solution Approach 2:
The patent uses composite material strategy by combining PVA with secondary cross-linking agents (such as borax, epichlorohydrin, or glutaraldehyde) to create a hybrid network that integrates the advantages of both physical and chemical cross-linking, achieving injectability with sustained mechanical stability.
2Reliability
If chemical cross-linking is used to improve mechanical properties and stability, then the hydrogel becomes non-injectable
Solution Approach 1:
The patent introduces dynamic characteristics to the cross-linked hydrogel system, where the material transitions from a rigid chemically cross-linked state to a flowable state during injection, then returns to structural integrity after implantation. This is achieved through thermal-responsive behavior or controlled degradation mechanisms.
Solution Approach 2:
The patent exploits phase transition phenomena where the chemically cross-linked hydrogel undergoes a reversible or irreversible phase change from solid gel to flowable state at injection temperature, enabling injection while maintaining the chemically cross-linked network structure for long-term stability.
3Strength
If high cross-linking density is used to increase modulus, then the hydrogel loses injectability
Solution Approach 1:
The patent optimizes the cross-linking density parameter to achieve a balance point where sufficient mechanical strength is obtained while maintaining injectability. This involves controlling cross-linker concentration, molecular weight, and cross-linking kinetics to create a network that is strong yet deformable under injection conditions.
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 hydrogel composition provides enhanced mechanical properties, stability, and biocompatibility, allowing for successful nucleus pulposus replacement with improved modulus and reduced degradation, facilitating minimally invasive procedures and long-term functionality.
Implementation Method 1
the hydrogel is flowable when heated above its melting point
Implementation Method 2
in a hydrogel they may be rendered insoluble generally due to the presence of covalent, ionic, or physical crosslinks
Implementation Method 3
Hydrogels are water-swellable or water-swollen materials whose structure is typically defined by a crosslinked or interpenetrating network of hydrophilic homopolymers or copolymers
Data Source
AI summary
An injectable hydrogel composition comprising: water; and poly(vinyl alcohol) chemically cross-linked with a second polymer to form a cross-linked resin, wherein the second polymer is selected from the group consisting of: a polyhydric alcohol compound, a polyvalent epoxy compound, a polyvalent amine compound, a dialdehyde compound, a diisocyanate compound, and mixtures thereof, wherein the cross-linked resin has a degree of cross-linking of from about 0.0001 mol/mL to about 0.002 mol/mL, and wherein the hydrogel is flowable when heated above its melting point.