Chitosan Oligosaccharide Hydrogels Homogeneous Gelation
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Solution Overview
Problem
Chitosan-based hydrogels often form non-homogeneous precipitates at neutral pH when combined with boric acid, limiting their application in biomedical and pharmaceutical fields due to uncontrolled gelation and phase separation.
Innovation Solution
A process involving the solubilization of chitosan oligosaccharide derivatives in water at pH 4-8, followed by the addition of a boric acid solution and a homogenizing reagent such as mannitol or sodium bicarbonate, under stirring, to form homogeneous hydrogels that avoid precipitation and exhibit controlled gelation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chitosan is combined with boric acid at neutral pH, then gelation occurs, but non-homogeneous precipitates form
Solution Approach 1:
The patent applies preliminary action by adjusting the pH to acidic conditions (pH 2-4) before adding boric acid to chitosan. This pre-adjustment of pH ensures that chitosan remains soluble and prevents premature precipitation, allowing controlled gelation to occur uniformly throughout the solution rather than forming localized precipitates.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying pH as the key control parameter. The process transitions from acidic pH (2-4) during mixing to neutral pH (6-8) during gelation. This parameter transformation enables controlled gelation while maintaining homogeneity, resolving the contradiction between achieving gelation and preventing precipitate formation.
2Quantity of substance
If chitosan with medium to high molecular weight and low N-acetyl-glucosamine fraction is used, then solubility at neutral pH decreases, but precipitation occurs
Solution Approach 1:
The patent applies parameter changes by controlling pH as the critical factor. By maintaining acidic pH (2-4) during the mixing phase, the patent ensures high solubility of chitosan regardless of its molecular weight or N-acetyl-glucosamine fraction. This pH control prevents precipitation and enables homogeneous gel formation even with chitosan that would normally precipitate at neutral pH.
3Manufacturing precision
If acidic conditions are used to maintain chitosan solubility, then homogeneous gelation is achieved, but biocompatibility may be compromised
Solution Approach 1:
The patent applies preliminary action by performing the pH adjustment and gelation process in acidic conditions first, then allowing the system to naturally buffer to neutral pH. This sequential approach ensures homogeneous gelation occurs under controlled acidic conditions, after which the final product achieves neutral pH for improved biocompatibility.
Solution Approach 2:
The patent utilizes periodic action through the time-dependent pH transition. The system undergoes a periodic change from acidic pH during mixing and initial gelation to neutral pH in the final hydrogel product. This temporal separation allows homogeneous gelation to occur in acidic conditions while the final product achieves biocompatible neutral pH.
Data Source
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AI summary
The invention concerns a process for the preparation of hydrogels from chitosan oligosaccharide derivatives and boric acid, which allows to obtain homogeneous hydrogels avoiding the formation of precipitates. In another aspect, a hydrogel obtainable from this process is described. The use of the hydrogels in the biomedical and pharmaceutical fields for applications such as viscosupplementation, as a substitute for the extracellular matrix, and as a drug delivery system are also described.