Biocompatible Sponge Laminate for Layered Adhesion Prevention

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Solution Overview

Problem

Existing adhesion-preventing materials are either non-biodegradable, ineffective against serious adhesions, or interfere with wound healing, and lack versatility in application methods.

Innovation Solution

A biocompatible sponge-like laminate with two layers of low-endotoxin monovalent metal salts of alginic acid, differing in molecular weight and dissolution rates, is used to prevent adhesions by ensuring the higher molecular weight layer remains at the wound while the lower molecular weight layer dissolves faster, providing effective adhesion prevention without interfering with healing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a PTFE film is used as an adhesion-preventing barrier, then adhesion prevention effectiveness is improved, but biodegradability deteriorates (material remains in the body)

Engineering Contradiction:
Improveadhesion prevention effectivenessVSAvoidbiodegradability
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent changes the material composition parameters by using biodegradable polymers (gelatin, alginate, chitosan) instead of non-biodegradable PTFE, while adjusting molecular weight, crosslinking degree, and composition ratios to maintain adhesion prevention effectiveness. This resolves the contradiction by transforming the material from non-biodegradable to biodegradable while preserving functional performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates composite adhesion-preventing materials by combining multiple biodegradable polymers (gelatin with alginate, chitosan with gelatin) in specific ratios. This composite approach allows the material to achieve both biodegradability and effective adhesion prevention, resolving the contradiction between these two properties.

Inventive Principle:
Principle #40Composite materials

2Loss of substance

If a sheet containing hyaluronic acid and carboxymethyl cellulose is used, then biodegradability is improved, but adhesion prevention effectiveness deteriorates (cannot completely prevent serious adhesions)

Engineering Contradiction:
ImprovebiodegradabilityVSAvoidadhesion prevention effectiveness
Core Design Contradiction:
Loss of substanceVSReliability

Solution Approach 1:

The patent adjusts critical parameters including increasing molecular weight of gelatin to 80,000-500,000 and optimizing crosslinking degree to 10-50%, which significantly enhances adhesion prevention effectiveness while maintaining biodegradability. This resolves the contradiction by optimizing material parameters to achieve both properties simultaneously.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent develops composite materials combining gelatin with alginate or chitosan in specific ratios (gelatin:alginate = 9:1 to 1:9, gelatin:chitosan = 9:1 to 1:9). This composite structure synergistically improves adhesion prevention effectiveness while preserving biodegradability, resolving the contradiction between these properties.

Inventive Principle:
Principle #40Composite materials

3Reliability

If the molecular weight of alginic acid salt in the first layer is increased, then adhesion prevention effectiveness is improved, but dissolution rate deteriorates (slower dissolution)

Engineering Contradiction:
Improveadhesion prevention effectivenessVSAvoiddissolution rate
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent applies local quality by creating a two-layer structure where each layer has different molecular weights tailored to its specific function. The first layer uses high molecular weight (25,000-500,000) for effective adhesion prevention, while the second layer uses low molecular weight (3,000-100,000) for rapid dissolution. This resolves the contradiction by assigning different molecular weight qualities to different locations/layers.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the adhesion-preventing material into two distinct layers with different molecular weights and dissolution rates. This segmentation allows each layer to independently perform its optimized function, resolving the contradiction between adhesion prevention effectiveness and dissolution rate that would exist in a single uniform material.

Inventive Principle:
Principle #1Segmentation

4Reliability

If a biodegradable adhesion-preventing material is used, then biocompatibility is improved, but application versatility deteriorates (limited application methods)

Engineering Contradiction:
ImprovebiocompatibilityVSAvoidapplication versatility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent designs the adhesion-preventing material with multi-functionality to enable various application methods including sheet form application, injection as gel, and coating. The material can be applied before, during, or after surgery, and can be used in open surgery, laparoscopic surgery, and robotic surgery. This universality resolves the contradiction by making the biodegradable material adaptable to multiple application scenarios.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 laminate effectively prevents both wound and de novo adhesions, is safe for the body, allows easy application via endoscopic surgery, and can be reattached for position adjustment, offering superior adhesion prevention compared to existing materials.

Implementation Method 1

a weight average molecular weight of the monovalent metal salt of alginic acid in the first layer is 25,000-500,000, a weight average molecular weight of the monovalent metal salt of alginic acid in the second layer is 3,000-100,000... the weight average molecular weight of the monovalent metal salt of alginic acid in the first layer is higher than the weight average molecular weight of the monovalent metal salt of alginic acid in the second layer

Methodology Applied
Scientific EffectDissolution rate difference based on molecular weight:

Data Source

PatentEP3485921B1Adhesion-preventing composition
Publication Date: 2025.07.23 MOCHIDA PHARM CO LTD
  • EP3485921B1 patent drawingFigure 1~2
  • EP3485921B1 patent drawingFigure 3(A)~3(B)
  • EP3485921B1 patent drawingFigure 3(C)

AI summary

[Problem] An adhesion-preventing material having a high adhesion-preventing effect has been demanded. [Solution] An adhesion-preventing material including a sterilized biocompatible sponge-like laminate, wherein the sponge-like laminate comprises a sponge-like first layer and a sponge-like second layer each of which is at least partially crosslinked with a curing agent and comprises a low-endotoxin alginic acid monovalent metal salt, the alginic acid monovalent metal salt in the first layer has a weight average molecular weight of 10,000 to 2,000,000, the alginic acid monovalent metal salt in the second layer has a weight average molecular weight of 1,000 to 1,000,000, the weight average molecular weights are measured by a GPC-MALS method after a decrosslinking treatment, and the weight average molecular weight of the alginic acid monovalent metal salt in the first layer is higher than that in the second layer.