Shape Memory Silk Fibroin Materials for Biocompatible Tissue Integration

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Solution Overview

Problem

Current shape memory polymers face challenges in biocompatibility, mechanical integrity when wet, controlled degradation, and integration with tissue, often resulting in immune responses and unpredictable degradation kinetics.

Innovation Solution

Development of silk fibroin-based materials with specific molecular weight ranges and the incorporation of plasticizers, processed through controlled lyophilization and thermally conductive molds, enabling rapid recovery and volumetric expansion without plastic deformation, facilitating biocompatibility and predictable degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If current shape memory polymers are used, then shape recovery function is achieved, but biocompatibility and immune response issues occur

Engineering Contradiction:
Improveshape recovery functionVSAvoidimmune response
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameter by using silk fibroin (a natural protein) instead of conventional synthetic polymers, and controls molecular weight parameters (3-400 kDa range) to achieve both shape memory functionality and biocompatibility. This parameter transformation resolves the contradiction between shape recovery and immune response.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates composite materials by combining silk fibroin with plasticizers (such as glycerol at 10-40% w/w) to achieve the desired balance between shape memory properties and biocompatibility. The composite structure allows simultaneous optimization of mechanical integrity, shape recovery, and biological compatibility.

Inventive Principle:
Principle #40Composite materials

2Reliability

If shape memory polymers are used, then shape recovery is achieved, but mechanical integrity when wet deteriorates

Engineering Contradiction:
Improveshape recoveryVSAvoidmechanical integrity when wet
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent optimizes the molecular weight parameter of silk fibroin (3-400 kDa range) and controls the plasticizer content (10-40% w/w) to maintain mechanical integrity in wet conditions while preserving shape memory functionality. The specific parameter ranges ensure adequate strength when wet.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces plasticizers as intermediary substances that mediate between the silk fibroin matrix and water environment. These plasticizers (e.g., glycerol) improve water compatibility and prevent excessive softening when wet, thereby maintaining mechanical integrity during shape recovery processes.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If shape memory polymers are used, then shape recovery function is achieved, but degradation kinetics become unpredictable

Engineering Contradiction:
Improveshape recovery functionVSAvoiddegradation kinetics control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent precisely controls the molecular weight parameter of silk fibroin (3-400 kDa) and the plasticizer concentration (10-40% w/w) to achieve predictable degradation kinetics. By establishing specific parameter ranges, the patent transforms unpredictable degradation into a controllable process that can be tailored for different applications.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If shape memory polymers are used, then shape recovery is achieved, but integration with tissue deteriorates

Engineering Contradiction:
Improveshape recoveryVSAvoidtissue integration
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the material composition parameter by using silk fibroin, a natural protein with proven biocompatibility and tissue compatibility. The molecular weight control (3-400 kDa) and plasticizer optimization enable both shape memory function and effective tissue integration, resolving the contradiction between these two requirements.

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 silk fibroin-based materials exhibit rapid recovery up to 50 times volume expansion, maintain biocompatibility, and show predictable degradation kinetics, allowing for minimally invasive implantation and effective tissue integration.

Implementation Method 1

Stimuli-responsive polymers are a subclass of 'smart' materials that can recover from a deformed shape back to an original, pre-defined shape in the presence of an external stimuli. Materials exhibiting this behavior are often known as shape memory polymers (SMPs).

Methodology Applied
Scientific EffectShape memory effect: Shape Memory Polymer

Implementation Method 2

processed through controlled lyophilization

Methodology Applied
Scientific EffectLyophilization: Freeze Drying

Implementation Method 3

processed through controlled lyophilization and thermally conductive molds

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4116318A1Shape memory silk materials
Publication Date: 2023.01.11 TUFTS UNIV
  • EP4116318A1 patent drawingFigure 1
  • EP4116318A1 patent drawingFigure 2
  • EP4116318A1 patent drawingFigure 3A~3D

AI summary

The present application relates to silk fibroin-based materials, methods for making and using the same. Provided materials exhibit shape memory characteristics while showing comparable or better volumetric swelling, biocompatibility and/or degradability when compared to current memory polymers derived from either natural or synthetic materials.