Biodegradable Amphiphilic Shape Memory Polymers for Bone Grafts

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current synthetic polymer scaffolds for tissue engineering face challenges in maintaining mechanical properties after shape recovery in aqueous environments and achieving stable integration with hydroxyapatite, leading to inadequate structural and biological performance in biomedical applications.

Innovation Solution

Development of biodegradable triblock amphiphilic shape memory polymers (SMPs) such as poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(lactide-co-glycolide) (PELGA) that exhibit tunable hydrolytic degradation and enhanced integration with hydroxyapatite, supporting cell attachment and osteogenesis, and displaying hydration-induced stiffening due to PEG crystallization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional synthetic polymer scaffolds are used for tissue engineering, then structural framework is provided, but mechanical properties are lost after shape recovery in aqueous environments

Engineering Contradiction:

Improvemechanical propertiesVSAvoidstability after shape recovery

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the polymer by incorporating PEG segments with specific molecular weights (2,000-20,000 Daltons) and controlling the ratio of hydrophilic to hydrophobic segments. This compositional parameter change enables the polymer to maintain mechanical strength after shape recovery in aqueous environments, resolving the contradiction between strength and reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polymer structure combining hydrophilic PEG segments with hydrophobic segments (such as polylactide, polyglycolide, or polycaprolactone). This composite architecture at the molecular level allows the material to exhibit both shape memory behavior and enhanced mechanical stability after shape recovery, simultaneously achieving strength and reliability.

Inventive Principle:

Principle #40Composite materials

2Strength

If hydrophobic polymers are used, then structural integrity is maintained, but integration with hydroxyapatite is poor

Engineering Contradiction:

Improvestructural integrityVSAvoidintegration with hydroxyapatite

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies local quality by creating amphiphilic polymers with distinct hydrophilic PEG segments and hydrophobic segments in specific arrangements. The hydrophilic segments locally interact with hydroxyapatite surfaces through hydrogen bonding and electrostatic interactions, while hydrophobic segments maintain structural integrity, thus resolving the contradiction between structural integrity and integration with hydroxyapatite.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes the phase transition behavior of PEG segments, which can transition from crystalline to amorphous states upon hydration. This phase transition enhances the polymer's ability to interact with hydroxyapatite while maintaining structural integrity, effectively resolving the contradiction between strength and integration reliability.

Inventive Principle:

Principle #36Phase transitions

3Ease of operation

If shape memory polymers are designed for self-wrapping, then surgical handling is improved, but mechanical strength may be compromised

Engineering Contradiction:

Improvesurgical handlingVSAvoidmechanical strength

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The patent designs polymers with dynamic mechanical properties that can adapt to different operational states. During surgical handling, the polymers exhibit enhanced flexibility and elasticity due to PEG crystallization upon hydration, facilitating self-wrapping. After deployment, the same dynamic properties allow the material to maintain adequate mechanical strength, resolving the contradiction between ease of operation and mechanical strength.

Inventive Principle:

Principle #15Dynamics

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 SMPs maintain or enhance mechanical properties after shape recovery, facilitating stable fixation and integration with hydroxyapatite, enabling effective self-wrapping around bone grafts and promoting bone regeneration with improved surgical handling and biological performance.

Implementation Method 1

displaying hydration-induced stiffening due to PEG crystallization

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 2

biodegradable triblock amphiphilic shape memory polymers (SMPs)

Methodology Applied

Scientific EffectShape memory polymer effect: Shape Memory Polymer

Implementation Method 3

exhibit tunable hydrolytic degradation

Methodology Applied

Scientific EffectHydrolysis: Hydrolysis

Data Source

PatentUS11453746B2Biodegradable amphiphilic shape memory polymers and compositions and methods thereof

Publication Date: 2022.09.27 UNIV OF MASSACHUSETTS

AI summary

The invention relates to compositions of co-polymers having hydrophilic and biodegradable hydrophobic units or blocks, resulting in improved properties and functionalities suitable for biomedical applications as self-fitting tissue scaffolds or minimally invasive surgical implants.