Degradable Hydrogel with Tunable Ester Linkages
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Solution Overview
Problem
Existing degradable hydrogel systems face challenges in achieving predictable and broadly tunable degradation rates without significant changes in macroscopic properties, which is crucial for biomedical applications like drug delivery and tissue regeneration.
Innovation Solution
A bioorthogonally crosslinked hydrogel platform using four-armed poly(ethylene glycol) macromers with strategically placed labile ester linkages, allowing for predictable tuning of degradation profiles via click chemistry, enabling the formation of hydrogels with consistent mechanical properties and controlled disintegration times from 2 days to 250 days or longer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If labile linkages with varying cleavage rates are incorporated to control degradation, then degradation rate is improved, but macroscopic properties change significantly
Solution Approach 1:
The patent divides the hydrogel network into two distinct linkage types: stable crosslinks (forming the structural backbone) and labile linkages (controlling degradation). This segmentation allows independent optimization of mechanical properties through stable crosslinks while degradation kinetics are controlled by the labile linkage composition, resolving the contradiction between maintaining stable macroscopic properties and achieving controllable degradation rates.
Solution Approach 2:
The patent applies local quality by placing labile linkages specifically at network chain positions rather than throughout the entire structure. The stable crosslinks maintain the hydrogel's macroscopic integrity and mechanical properties, while the locally positioned labile linkages degrade at controlled rates, enabling degradation tuning without compromising overall structural stability.
2Duration of action of moving object
If polymer network structure is altered to control degradation, then degradation profile is improved, but other macroscopic properties change undesirably
Solution Approach 1:
The patent extracts the degradation control function from the overall network structure by introducing specific labile linkage components (e.g., ester bonds, disulfide bonds) that can be independently tuned. This allows the degradation profile to be modified by changing linkage composition without altering the fundamental network architecture that provides mechanical strength, thus resolving the contradiction between degradation control and property stability.
3Duration of action of moving object
If composition-dependent changes are made to control degradation, then degradation rate is improved, but network structure stability deteriorates
Solution Approach 1:
The patent creates a composite hydrogel network combining two types of linkages with fundamentally different stability characteristics. The stable crosslinks (e.g., amide bonds, ether bonds) provide reliable structural support, while the labile linkages (e.g., ester bonds, anhydride bonds) provide controlled degradation. This composite approach allows independent optimization of both network reliability and degradation rate through compositional adjustment.
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 platform achieves precise control over hydrogel degradation rates, maintaining robust mechanical properties and allowing for the formulation of hydrogels with predictable disintegration times, addressing the limitations of existing systems by providing a versatile and cytocompatible solution for biomedical applications.
Implementation Method 1
a bioorthogonally crosslinked network of a first set of macromers and a second set of macromers, wherein the first set of macromers comprises a macromer (i) having the structural formula of: wherein R 1 is a group comprising -N 3 , X is an ester group, and each n is independently an integer from 1 to about 400; and a macromer (ii) having the structural formula of: wherein R 1 is a group comprising -N 3 , X is empty, and each n is independently an integer from 1 to about 400; and the second set of macromers have the structural formula of: wherein R 2 is a group comprising a cyclic or acylic alkyne group, Y is NH, O, or empty, and each m is independently an integer from 1 to about 400, wherein the first and second reactive end groups are joined via click chemistry to form a crosslinked network
Implementation Method 2
X is an ester group... the one or more labile and/or stable linkage(s) are configured within the crosslinked network so as to provide a controllable and predictable gelling kinetics and/or disintegration profile of the hydrogel
Data Source
Figure 1
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Figure 3(A)~3(C)
AI summary
The invention provides a novel approach to hydrogels with predictable degradation/gelling kinetics, which is useful for many biomedical applications where appropriate gelling kinetics and the timely disintegration of the hydrogel (e.g., drug delivery, guided tissue regeneration) is required. Precisely controlling hydrogel degradation over a broad range in a predictable manner is achieved via a simple but versatile hydrogel platform that allows formulation of hydrogels with predictable disintegration time from within 2 days to >250 days yet comparable macroscopic physical properties.