Zwitterionic Microgels for Self-Healing Injectable Hydrogels
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Solution Overview
Problem
Current injectable hydrogels face challenges in achieving biocompatibility, physiological stability, and ease of use for biomedical applications, particularly in forming self-healing, malleable, and tissue-like materials that can be easily sterilized and stored, while maintaining covalent crosslinking for strength and elasticity.
Innovation Solution
Development of self-healing zwitterionic and mixed charge microgels with covalent crosslinking and supramolecular interactions, which can be lyophilized into powders for simplified storage and reconstituted into injectable, malleable hydrogels with tunable viscoelasticity, suitable for biomedical applications such as tissue fillers and cell scaffolds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If in situ forming hydrogels are used to achieve injectability, then the hydrogel can be injected through a needle, but the gel cannot be significantly re-shaped once formed and requires complex polymer architectures
Solution Approach 1:
The invention divides the hydrogel into pre-formed microgel beads (1-1000 micrometers in diameter) that are suspended in a solution. These discrete microgel units are then assembled in situ to form the injectable hydrogel construct, simplifying the overall architecture while maintaining injectability and re-shapability
Solution Approach 2:
The hydrogel employs dynamic reversible crosslinking mechanisms (metal-ligand coordination, hydrogen bonding, or host-guest interactions) that allow the gel to be re-shaped multiple times after injection, unlike irreversible covalent crosslinking. This dynamic nature enables both injectability and post-injection malleability
2Adaptability or versatility
If physical crosslinking is used to enable repeated switching between solid-like and liquid-like forms, then the hydrogel is more practical for clinical applications, but the gels are relatively weak and short-lived in vivo
Solution Approach 1:
The invention merges physical crosslinking (reversible, enables flow and self-healing) with covalent crosslinking (irreversible, provides structural strength) within the same microgel network. This hybrid approach gives the hydrogel both the practical handling properties of physical gels and the in vivo stability of covalent gels
Solution Approach 2:
The hydrogel uses composite crosslinking strategies combining multiple bonding types (covalent bonds plus physical interactions like metal-coordination or hydrogen bonding) to achieve a material that exhibits both reversibility for clinical handling and stability for in vivo performance
3Object-affected harmful factors
If zwitterionic polymers are used to achieve ultra-low nonspecific protein fouling, then biocompatibility is improved, but no straightforward route to injectable or malleable pure zwitterionic hydrogels has been reported
Solution Approach 1:
The invention uses pre-formed zwitterionic microgel beads as building blocks that can be easily handled, suspended, and injected. This segmented approach bypasses the difficulty of forming injectable pure zwitterionic hydrogels directly while maintaining the ultra-low protein fouling properties of zwitterionic polymers
Solution Approach 2:
The microgel beads act as intermediaries that facilitate injection and malleability while the zwitterionic polymer chains on their surfaces maintain biocompatibility and resist protein fouling. The beads enable practical handling without compromising the biochemical properties
4Ease of manufacture
If lyophilized ZIP powders are used for simplified storage and sterilization, then ease of manufacture is improved, but the powders must rapidly self-heal into homogeneous composite hydrogel formulation upon reconstitution
Solution Approach 1:
The lyophilized microgel beads possess self-healing properties that enable them to automatically reassemble into a homogeneous hydrogel formulation upon contact with aqueous solutions, without requiring external energy input, specialized reagents, or complex processing steps
Solution Approach 2:
The microgels are pre-crosslinked and pre-formed as stable powders before sterilization and storage. This preliminary formation ensures that upon reconstitution, they rapidly self-assemble into homogeneous gels without requiring complex in-situ crosslinking chemistry or specialized equipment
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 zwitterionic injectable pellet (ZIP) constructs demonstrate high biocompatibility, maintain strength and elasticity upon rehydration, and exhibit efficient self-healing properties, making them suitable for various clinical applications including drug delivery and cell preservation without requiring specialized reagents or conditions.
Implementation Method 1
Many gels in this category are based on polysaccharides, such as alginate, dextran, and hyaluronic acid; these natural polymers can reversibly crosslink by chelating divalent ions such as Ca 2+
Implementation Method 2
These are commonly used for injectable drug formulations, their lack of covalent crosslinking makes them relatively weak and short-lived in vivo
Implementation Method 3
Zwitterionic polymer brushes, hydrogels, and elastomers confer ultra-low levels of nonsspecific protein fouling from complex physiological fluids, exceeding the performance of popular hydrophilic or amphiphilic polymers like poly(ethylene glycol) (PEG)
Implementation Method 4
The combination of covalent crosslinking inside each microgel and supramolecular interactions between them gives the resulting zwitterionic injectable pellet (ZIP) constructs supportive moduli and tunable viscoelasticity. Lyophilized ZIP powders retain their strength and elasticity upon rehydration
Data Source
Figure 1A~1G
Figure 2A~2D
Figure 3A~3E
AI summary
Zwitterionic microgels, zwitterionic microgel assemblies, their formulations and methods for their use.