Biocompatible Block-Copolymer Membrane for Tissue Engineering

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Solution Overview

Problem

Current biomedical membranes face challenges in achieving biodegradability, sterilizability, mechanical properties, and uniform porous structures, which are essential for medical applications, while also needing to comply with stringent regulatory requirements.

Innovation Solution

A biocompatible block-copolymer membrane is developed through polycondensation, featuring controlled degradability and mechanical properties, with a uniform porous structure and permeability, achieved by specific chemical composition and processing methods, including the use of diisocyanate, diacid halides, and phosgene reactions, and phase separation techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If a polymer membrane is designed to be biodegradable, then it can be used in temporary medical implants, but the mechanical strength and durability are reduced

Engineering Contradiction:
Improveservice lifeVSAvoidmechanical strength
Core Design Contradiction:
Duration of action of moving objectVSStrength

Solution Approach 1:

The patent employs block copolymers consisting of different polymer blocks with complementary properties. The crystalline blocks (e.g., polyglycolic acid) provide mechanical strength and structural stability, while the amorphous blocks (e.g., polyε-caprolactone) provide flexibility and controlled degradability. This composite structure at the molecular level allows the membrane to maintain mechanical integrity during its service life while being biodegradable.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The membrane exhibits different properties in different regions: the crystalline domains provide strength and stability where needed, while the amorphous domains provide degradability and flexibility. The phase-separated structure creates local regions with distinct functions, allowing simultaneous achievement of mechanical strength and controlled degradation.

Inventive Principle:
Principle #3Local quality

2Quantity of substance

If the membrane is made highly porous to improve permeability, then mass transport is enhanced, but the mechanical strength decreases

Engineering Contradiction:
ImprovepermeabilityVSAvoidmechanical strength
Core Design Contradiction:
Quantity of substanceVSStrength

Solution Approach 1:

The block copolymer system creates a composite structure where the crystalline phases form a supportive network that maintains mechanical strength even when the membrane is highly porous. The amorphous phases fill the spaces and provide flexibility, allowing high porosity without sacrificing structural integrity.

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If the membrane structure is made uniform and symmetric, then manufacturing control is improved, but the degradability control becomes more difficult

Engineering Contradiction:
Improvestructure uniformityVSAvoiddegradability control
Core Design Contradiction:
Manufacturing precisionVSDuration of action of moving object

Solution Approach 1:

The patent controls degradability by changing the chemical composition parameters of the block copolymer, specifically the ratio of crystalline to amorphous blocks, the molecular weight of each block, and the composition of the amorphous block. These parameter changes allow precise control of degradation rate while maintaining uniform membrane structure through controlled phase separation during fabrication.

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 membrane exhibits excellent biocompatibility, controlled degradability, and mechanical performance, allowing for versatile applications in medical and veterinary fields, including tissue engineering and implant use, with tailored service life and reduced need for secondary surgeries.

Implementation Method 1

The film is then contacted with a fluid which is a non-solvent for the polymer, but which is miscible with the solvent to induce phase inversion of the film

Methodology Applied
Scientific EffectPhase separation: Phase Change

Implementation Method 2

A classical method is known as 'non-solvent induced phase separation' (NIPS)

Methodology Applied
Scientific EffectNon-solvent induced phase separation:

Implementation Method 3

The solvent diffuses outwards into the coagulation bath while the non-solvent diffuses into the cast film. The exchange of solvent and non-solvent yields a solution which becomes thermodynamically unstable resulting in the separation of the components

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP1862188B1Porous membrane comprising a biocompatible block-copolymer
Publication Date: 2018.02.28 ETH ZURICH
  • EP1862188B1 patent drawingFigure 1A~1B
  • EP1862188B1 patent drawingFigure 2
  • EP1862188B1 patent drawingFigure 3

AI summary

The invention relates to a membrane comprising a biocompatible block copolymer and has a porous structure with regularly distributed pores. A method for preparing said membranes is also provided.