Chitosan Bridging Hydrogel Adhesion for Rapid Tissue Bonding
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Solution Overview
Problem
Existing tissue adhesives face challenges in achieving strong, rapid adhesion without relying on covalent bonds, as they often require specific functional groups that can be disrupted by physiological fluids, leading to weak and time-consuming adhesion.
Innovation Solution
A double polymer network hydrogel system using a bridging polymer, such as chitosan, forms strong adhesion through non-covalent interactions like hydrogen bonding and chain entanglement, enabling ultra-tough adhesion (>2000J/m2) within minutes without the need for coupling agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If covalent bonding strategies with coupling reagents are used to achieve strong adhesion, then adhesion strength is improved, but the system becomes dependent on specific functional groups that can be disrupted by physiological fluids
Solution Approach 1:
The patent introduces a bridging polymer layer as an intermediary between the hydrogel and tissue surfaces. This bridging polymer forms non-covalent bonds (hydrogen bonds, electrostatic interactions, chain entanglements) with both surfaces, creating a stable adhesive interface that does not require specific reactive functional groups and is therefore resistant to disruption by physiological fluids
Solution Approach 2:
The patent changes the bonding mechanism from covalent to non-covalent interactions by modifying the chemical parameters of the adhesive system. The bridging polymer utilizes hydrogen bonding, electrostatic interactions, and physical entanglement instead of covalent bonds, fundamentally altering how adhesion is achieved and making it more stable in physiological environments
2Object-affected harmful factors
If non-covalent bonding strategies are used to avoid toxic chemicals, then safety is improved, but adhesion strength and speed deteriorate
Solution Approach 1:
The patent creates a composite adhesive system combining a tough hydrogel matrix with a bridging polymer layer. This composite structure leverages the benefits of both materials: the hydrogel provides biocompatibility and moisture content, while the bridging polymer contributes strong non-covalent bonding capabilities, achieving both safety and strength simultaneously
Solution Approach 2:
The patent applies different bonding mechanisms to different regions of the adhesive interface. The bridging polymer forms localized non-covalent bonds at the interface between the hydrogel and tissue, concentrating the bonding function where it is most needed while maintaining overall system safety
3Object-affected harmful factors
If topological wet adhesion is used to avoid chemical reactions, then biocompatibility is improved, but adhesion speed and strength deteriorate
Solution Approach 1:
The patent introduces dynamic bonding mechanisms where the bridging polymer can rapidly form and break non-covalent bonds during the adhesion process. The polymer chains dynamically adjust their configuration to maximize bonding interactions, enabling fast adhesion without requiring slow chemical reactions
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 system achieves rapid and robust adhesion between hydrogels and tissues or elastomers, providing unprecedented adhesion strength and versatility for biomedical applications.
Implementation Method 1
Chitosan deprotonation results in hydrogen bonding between polymer chains, leading to their entanglement and formation of molecular interlocks between the bridging polymer and the adherend matrix
Implementation Method 2
Chitosan deprotonation results in hydrogen bonding between polymer chains, leading to their entanglement and formation of molecular interlocks between the bridging polymer and the adherend matrix
Implementation Method 3
Hydrogel-based adhesives... have highlighted their versatility, biocompatibility, and tunability as tissue adhesives
Data Source
AI summary
The present disclosure shows that by combining pH-responsive bridging chitosan polymer chains and a tough hydrogel dissipative matrix one can achieve unprecedented ultra-tough adhesion to tissues (>2000J/m2) in 5-10 mins without covalent bond formation. The strong non-covalent adhesion was shown to be stable under physiologically relevant conditions and strongly influenced by chitosan molecular weight. molecular weight of polymers in the matrix, and pH. The adhesion mechanism relies primarily on the topological entanglement between the chitosan chains and the permeable adherends. The present disclosure also discloses dry polymer films to generate instant adhesion between hydrogel-hydrogel and hydrogel-elastomer surfaces. Unprecedented adhesive energies (>3000J/m2) between alginate-polyacrylamide tough hydrogels were achieved instantaneously using an intermediate chitosan film, governed by pH change, H-bonding, and bridging polymer entanglement. Furthermore, this strategy also generates instant strong adhesion between acrylic elastomers and tough hydrogels with adhesion energy as high as 4000J/m2.