Silver-Alginate Wound Dressing for Uniform Ion Distribution

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Solution Overview

Problem

Silver-based wound dressings face issues with non-uniform silver distribution and light-induced darkening, leading to visual imperfections and potential antibacterial efficacy inconsistencies.

Innovation Solution

A process involving the simultaneous contact of gel-forming fibres with a silver-containing solution, ensuring uniform silver ion distribution by dunking the fibres directly into the solution, minimizing the solution volume, and controlling the silver content to link silver ions to only some exchangeable sites, thereby achieving uniform silver take-up and photostability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If silver is applied to fibres by immersing into silver solution, then antibacterial properties are achieved, but uniform silver distribution is not obtained resulting in streakiness and discoloration

Engineering Contradiction:
Improveantibacterial efficacy consistencyVSAvoidsilver distribution uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The fibres are pre-treated with a crosslinking agent (e.g., borax) before silver application to create uniform reactive sites. This preliminary action ensures that when silver solution is applied, the silver ions distribute uniformly across all fibre surfaces, preventing streakiness and ensuring consistent antibacterial efficacy throughout the wound dressing.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A crosslinking agent serves as an intermediary substance that bridges the fibres and silver ions. The crosslinking agent creates uniform reactive sites on the fibre surfaces, mediating the interaction between silver ions and fibres to achieve uniform silver distribution and consistent antibacterial properties without direct fibre-silver contact that would cause non-uniform deposition.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If silver compounds are exposed to light, then antibacterial activity is maintained, but the product darkens causing unattractive visual aspect

Engineering Contradiction:
Improveantibacterial activityVSAvoidvisual appearance
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The crosslinked fibre matrix acts as an intermediary protective environment for the silver ions. This crosslinked structure stabilizes the silver ions and reduces their direct exposure to light, thereby maintaining antibacterial activity while minimizing light-induced darkening and preserving the visual appearance of the wound dressing.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The chemical structure of the fibre matrix is changed through crosslinking, which alters the physical and chemical environment around the silver ions. This parameter change in the matrix structure provides photostability to the silver-containing wound dressing, reducing darkening upon light exposure while maintaining the therapeutic antibacterial properties.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If excessive silver is added to ensure uniform distribution, then silver distribution uniformity is improved, but silver content consistency is compromised with potential areas of excessive silver

Engineering Contradiction:
Improvesilver distribution uniformityVSAvoidsilver content consistency
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

By pre-crosslinking the fibres before silver application, uniform reactive sites are created throughout the fibre matrix. This preliminary structuring allows for controlled and uniform silver ion uptake, ensuring that silver is distributed evenly without creating areas of excessive concentration, thus maintaining both uniformity and consistency of silver content.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The crosslinking degree of the fibre matrix is controlled to optimize silver uptake capacity. By adjusting the crosslinking parameters, the fibres are engineered to have uniform and controlled silver binding sites, ensuring consistent silver content distribution without excessive silver accumulation in any region, thereby maintaining both uniformity and dosage consistency.

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 process results in wound dressings with uniform silver distribution and improved photostability, reducing streakiness and discoloration, ensuring consistent antibacterial activity and aesthetic appeal.

Implementation Method 1

Carboxymethyl cellulose, in particular carboxymethylated lyocell, has the ability to absorb a great deal of water and to form a gel on its surface

Methodology Applied
Scientific EffectGel formation: Gel

Implementation Method 2

The carboxymethyl cellulose fibres are water-absorbent fibres which become moist and slippery or gelatinous upon the uptake of wound exudate

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 3

gel-forming fibres having silver ions linked thereto at some but not all exchangeable sites

Methodology Applied
Scientific EffectIon exchange: Ion Exchange

Data Source

PatentUS8828424B2Antibacterial wound dressing
Publication Date: 2014.09.09 CONVATEC LTD

AI summary

An antibacterial wound dressing is based on, or derived from, gel-forming fibres such as carboxymethyl cellulose or alginate fibres having silver ions linked thereto at some but not all of the exchangeable sites such that the distribution of silver ions over the exchangeable sites is substantially uniform. The silvered fibres for the wound dressing can be prepared by contacting an assembly of precursor gel-forming fibres having exchangeable sites under conditions which do not cause irreversible gelling of the fibres with an amount of a solution containing silver ions so as to link silver ions at some but not all of the exchangeable sites, the whole of the assembly of precursor gel-forming fibres being contacted essentially simultaneously with the entire solution containing silver ions.