Chitosan-Bound Polyurethane Hydrogel for Antibacterial Wound Dressings

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Solution Overview

Problem

There is a need for new materials for wound dressings that exhibit good antibacterial efficacy without releasing harmful components, are suitable for various wound types, and can be easily and quickly manufactured, while ensuring biocompatibility.

Innovation Solution

A polymer is produced by reacting an isocyanate-terminated prepolymer with chitosan to create a hydrated polyurethane hydrogel system where chitosan is covalently bound, providing antibacterial properties and a moist wound environment without releasing chitosan into the wound.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If chitosan is used as an antibacterial component in wound dressings, then antibacterial efficacy is improved, but the material may release chitosan into the wound which could reduce efficacy and cause unwanted effects

Engineering Contradiction:
Improveantibacterial efficacyVSAvoidrelease of chitosan into wound
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The chitosan is nested within the polymer matrix structure, where it is covalently bound and physically trapped within the hydrogel network. This nested configuration allows the chitosan to maintain its antibacterial properties while preventing its release into the wound environment, as the polymer matrix acts as a containment structure.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention creates a composite material system combining chitosan with polyether polyols and isocyanate to form a cross-linked hydrogel polymer. This composite structure integrates the antibacterial properties of chitosan with the biocompatibility and moisture-retaining properties of the polymer matrix, achieving both efficacy and safety through material composition.

Inventive Principle:
Principle #40Composite materials

2Object-generated harmful factors

If chitosan is covalently bound within the polymer, then chitosan release is prevented, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvechitosan release preventionVSAvoidmanufacturing process complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The invention merges the chitosan incorporation step with the polymer formation step. By reacting chitosan directly with the isocyanate-terminated prepolymer during polymer synthesis, the covalent binding of chitosan is achieved simultaneously with polymer network formation, eliminating the need for separate incorporation steps and simplifying the overall manufacturing process.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The chitosan is dissolved in aqueous liquid before being mixed with the prepolymer, preparing it in advance for covalent binding. This preliminary dissolution step ensures uniform distribution and reactive availability of chitosan groups, facilitating efficient covalent bonding during the polymerization process without requiring complex additional processing.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If the polymer is produced quickly and easily, then productivity is improved, but the quality and biocompatibility may be compromised

Engineering Contradiction:
Improvemanufacturing speedVSAvoidbiocompatibility and quality
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The polymerization reaction is self-regulating and self-completing, proceeding automatically when the prepolymer is mixed with chitosan and aqueous liquid. The reaction requires no external catalysts, temperature control, or complex processing steps, allowing rapid production while maintaining consistent quality and biocompatibility through the inherent chemistry of the materials.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention optimizes the parameters of the reaction mixture, including the ratios of prepolymer, chitosan, and aqueous liquid, to achieve rapid polymerization. By adjusting these parameters, the process achieves both speed and quality, producing a biocompatible polymer with proper cross-linking density and chitosan incorporation without requiring extended processing times or complex conditions.

Inventive Principle:
Principle #35Parameter changes

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 polymer supports wound healing by absorbing exudate and releasing moisture, exhibits antibacterial efficacy, and is easily produced, adheres well to various wound types, and is biocompatible.

Implementation Method 1

reacting the prepolymer in the reaction mixture to obtain the polymer... allowing the prepolymer in the reaction mixture to react with the chitosan, so that at least a portion of the chitosan, or preferably the entire amount of chitosan, is covalently bound within the polymer

Methodology Applied
Scientific EffectCovalent bonding: Chemical Bonding

Implementation Method 2

The polymer according to the invention can thus create a moist wound environment that supports wound healing by absorbing wound exudate and/or releasing moisture to the wound

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentEP3587456B1Method for the production of antibacterial chitosane-containing polymer for medical purposes, in particular for treating wounds
Publication Date: 2026.02.25 PAUL HARTMANN AG
  • EP3587456B1 patent drawingFigure 1~2
  • EP3587456B1 patent drawingFigure 3~4
  • EP3587456B1 patent drawingFigure 5~6

AI summary

The present invention relates to a method for producing a polymer for medical purposes, in particular for wound treatment. The invention also relates to the polymer obtained by the method itself, as well as its use in medicine and in wound dressings. In principle, the produced polymer provides a hydrated polyurethane hydrogel system or a hydrated polyurethane foam system in whose cross-linked polymer structure chitosan is firmly embedded, in particular by covalent incorporation. The produced polymers are characterized in particular by antibacterial efficacy and the firm encapsulation of the chitosan within the polymer network.