Shape-Memory Polysaccharides via Non-Solvent Crosslinking
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Solution Overview
Problem
Current crosslinking methods for hyaluronic acid (HA) using diepoxides in alkaline media fail to maintain the original shape of the material, leading to degradation and loss of structural integrity, which is crucial for applications like tissue engineering and biomedical uses.
Innovation Solution
Crosslinking HA in a non-solvent system using quaternary ammonium bases and polyfunctional epoxides, which allows for the retention of the 3D structure and reduces hydrolysis, resulting in a 'shape-memory' product with improved stability and biocompatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crosslinking is performed in alkaline medium using diepoxides, then chemical stability and biocompatibility are improved, but the original shape and structural integrity of the material are lost
Solution Approach 1:
The patent changes the fundamental parameter of the reaction medium from aqueous alkaline solution to organic non-solvent system. This parameter change allows the crosslinking reaction to proceed while preserving the 3D structure, as the organic solvent does not cause the material to dissolve or lose its shape memory characteristics.
Solution Approach 2:
The patent introduces quaternary ammonium bases as intermediary substances that enable the crosslinking reaction in organic non-solvent systems. These intermediaries facilitate the reaction between diepoxides and polysaccharide hydroxyl groups without requiring aqueous alkaline conditions, thus preserving the material's shape while achieving crosslinking.
2Productivity
If crosslinking is performed in alkaline medium, then crosslinking efficiency is improved, but hydrolysis of polysaccharide chains increases leading to molecular weight reduction
Solution Approach 1:
The patent changes the reaction medium parameter from aqueous to organic non-solvent system. This eliminates the water that causes hydrolysis of polysaccharide chains, while still allowing efficient crosslinking through the use of quaternary ammonium bases and diepoxides. The organic environment prevents molecular weight reduction while maintaining crosslinking efficiency.
Solution Approach 2:
The patent converts the typically harmful effect of water (causing hydrolysis) into a benefit by using organic non-solvent systems where water is excluded. This transforms the reaction environment from one that causes chain scission to one that preserves molecular weight while enabling crosslinking.
3Ease of operation
If solvent systems are used for HA crosslinking, then reaction homogeneity is improved, but the 3D structure and shape memory are lost
Solution Approach 1:
The patent uses quaternary ammonium bases as intermediaries that enable homogeneous crosslinking reactions in organic non-solvent systems. These intermediaries ensure uniform distribution and reaction throughout the material while the organic solvent system preserves the 3D structure, combining the benefits of both solvent and non-solvent approaches.
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
This method produces crosslinked HA that maintains its original geometry and structural integrity, with increased chemical stability and biocompatibility, enabling longer residence times and enhanced performance in biomedical applications.
Implementation Method 1
crosslinking the polysaccharide in a non-solvent system for the polysaccharide in the presence of quaternary ammonium bases and a polyfunctional epoxide
Implementation Method 2
crosslinking involves the formation of inter- or intra-chain covalent bonds which are formed by reacting the polysaccharide with multifunctional molecules able to form covalent bonds with the hydroxyl and carboxyl moieties present on HA
Implementation Method 3
In aqueous solution the HA molecules trap large amounts of water (about 1000 times the weight of HA), taking on the form of extended spirals stabilised by the hydrogen bonds between the hydroxyl groups along the chain
Data Source
AI summary
Disclosed is an innovative method for the production of crosslinked polysaccharides which have the characteristic of maintaining the shape of the original solid matrix, and are therefore called shape-memory polysaccharides. The process according to the invention involves crosslinking at least one water-soluble polysaccharide, in particular hyaluronic acid and hyaluronans, chondroitin, chondroitin sulphate and chitosan, with at least one polyfunctional epoxy crosslinking agent, operating in a biphasic system consisting of the polysaccharide matrix, which always remains in the solid state throughout the crosslinking process, and a non-solvent system for the polysaccharide. The materials obtained by the process according to the invention are insoluble in aqueous systems and maintain their original shape after hydration. The process according to the invention is particularly important in -the preparation of crosslinked shape-memory polysaccharides for clinical applications and in the field of aesthetic medicine.