Bioabsorbable PLLA/PPCP Blend for Vascular Scaffolding

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Solution Overview

Problem

Conventional bioabsorbable polymer coatings for cardiovascular devices, such as stents, face challenges with mechanical strength and biocompatibility, leading to chronic inflammatory reactions and stent thrombosis due to inadequate phosphorylcholine group distribution on the surface.

Innovation Solution

A bioabsorbable blend of poly(L-lactide) (PLLA) and a phosphorylcholine group-containing copolymer (PPCP), specifically 2-methacryloxyethyl phosphorylcholine (MPC), is developed to enhance mechanical strength and biocompatibility by forming a phosphorylcholine-rich surface that prevents protein denaturation and platelet adhesion, reducing inflammatory reactions and thrombosis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If PLLA is used as a coating for temporary scaffolding, then mechanical strength is improved, but chronic inflammatory reactions occur due to poor biocompatibility

Engineering Contradiction:

Improvemechanical strengthVSAvoidchronic inflammatory reactions

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent combines PLLA (providing mechanical strength) with PPCP containing phosphorylcholine groups (providing biocompatibility and anti-thrombogenic properties). This composite blend maintains the structural integrity of PLLA while adding the blood-compatible characteristics of phosphorylcholine, thereby reducing chronic inflammatory reactions and platelet adhesion without sacrificing mechanical strength.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent creates a surface layer enriched with phosphorylcholine groups through the PPCP component. This localized concentration of biocompatible groups at the surface provides anti-thrombogenic and anti-inflammatory properties where they are most needed (in contact with blood), while the bulk PLLA maintains its mechanical support function.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If conventional PPCP coating is applied to metallic stents, then biocompatibility is improved, but phosphorylcholine groups are not efficiently detected on the surface

Engineering Contradiction:

ImprovebiocompatibilityVSAvoidphosphorylcholine group detection

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent merges the structural support function of PLLA with the surface-active phosphorylcholine groups of PPCP into a single integrated blend. This ensures that phosphorylcholine groups are inherently present throughout the material matrix and prominently displayed on the surface, eliminating detection issues associated with thin conventional coatings while maintaining robust biocompatibility.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If stent scaffolding is provided to prevent thrombosis, then reliability is improved, but stent thrombosis still occurs more than one year after implantation due to biodegradation

Engineering Contradiction:

Improvethrombosis preventionVSAvoidscaffolding duration

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent modifies the degradation parameters of the stent material by using high-molecular-weight PLLA combined with PPCP. This combination provides controlled biodegradation where the scaffolding maintains its mechanical strength and thrombosis-preventing properties for the required duration (more than one year), then gradually degrades into harmless lactic acid and phosphorylcholine metabolites that are safely eliminated by the body.

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 PLLA/PPCP blend exhibits improved mechanical strength and stable biodegradation patterns, reducing chronic inflammatory reactions and thrombosis risks, while maintaining similar Young's modulus to PLLA, making it suitable for various medical devices like stents.

Implementation Method 1

Poly(L-lactide) (PLLA) is a bioabsorbable polymer hydrolyzing into lactic acid under aqueous conditions

Methodology Applied

Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

forming a phosphorylcholine-rich surface that prevents protein denaturation and platelet adhesion

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS9138511B2Bioabsorbable blend for temporary scaffolding of the blood vessel wall

Publication Date: 2015.09.22 DOTTER INC

AI summary

A bioabsorbable blend comprising poly(L-lactide) (PLLA) and a phosphorylcholine group-containing copolymer (PPCP) capable of enduring the mechanical strength of blood vessel walls and applicable for fabricating cardiovascular devices was developed. The blend acts as a scaffold to support blood vessel walls during vascular healing and undergoes biodegradation in vivo after vascular healing is complete. Furthermore, the blend can prevent the formation and adsorption of thrombi.