Coatings for the manufacture and application of polyhydroxyalkanoate medical devices

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Solution Overview

Problem

There is a need for absorbable braided sutures with high initial tensile strength, prolonged strength retention in vivo, good knot security, low tissue drag, and biocompatibility, particularly for PHA braided sutures, where existing coatings do not adequately reduce tissue drag without altering the mechanical and thermal properties of the fiber.

Innovation Solution

Development of biocompatible coatings and spin finishes, such as Tween® 20, applied to PHA polymers to reduce tissue drag and improve processing without damaging the fibers, while maintaining the inherent properties of the PHA polymer, and subsequent removal of the spin finish to ensure cytotoxicity compliance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If coatings are applied to PHA braided sutures to reduce tissue drag, then lubricity is improved, but the mechanical and thermal properties of the fiber may be adversely altered

Engineering Contradiction:

Improvetissue dragVSAvoidmechanical properties of fiber

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent applies polyethylene glycol (PEG) as an intermediary coating substance that reduces tissue drag while maintaining fiber integrity. PEG serves as a mediator between the PHA fiber and tissue, providing lubricity without chemically reacting with or degrading the fiber structure, thus resolving the contradiction between reducing tissue drag and preserving mechanical properties

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the surface parameters of the PHA fiber by applying a PEG coating, which changes the surface properties to reduce friction and tissue drag. This parameter change affects only the surface characteristics while leaving the bulk mechanical and thermal properties of the PHA fiber unchanged, thereby resolving the contradiction

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If spin finish is applied to PHA fibers to facilitate processing, then ease of manipulation is improved, but residues may remain that could be cytotoxic

Engineering Contradiction:

Improveease of manipulation during processingVSAvoidcytotoxicity from residues

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent uses water-soluble spin finishes that can be easily removed after serving their temporary purpose during processing. The spin finish is applied to facilitate manipulation during textile processing, then completely removed through water washing, leaving no cytotoxic residues. This approach treats the spin finish as a temporary, disposable aid that is discarded after use

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent employs spin finishes that are deliberately discarded through water washing after they have fulfilled their function during processing. The water-soluble nature of the spin finish allows for complete removal and recovery of the PHA fiber without any harmful residues, resolving the contradiction between ease of manipulation and cytotoxicity

Inventive Principle:

Principle #34Discarding and recovering

3Object-affected harmful factors

If coatings are applied to PHA sutures to improve lubricity, then tissue drag is reduced, but the coating may react with or dissolve the fiber

Engineering Contradiction:

Improvetissue dragVSAvoidchemical compatibility with fiber

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent selects polyethylene glycol (PEG) as a coating material that is chemically homogeneous and compatible with the PHA fiber structure. PEG does not react with or dissolve the PHA polymer, maintaining chemical compatibility while providing the desired lubricity. This chemical homogeneity and compatibility resolve the contradiction between reducing tissue drag and ensuring fiber stability

Inventive Principle:

Principle #33Homogeneity

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 coatings and spin finishes effectively reduce tissue drag, enhance processing without fiber damage, and ensure biocompatibility, while maintaining the mechanical properties of PHA polymers, allowing for the production of high-strength medical devices like sutures and textiles with improved handling characteristics.

Implementation Method 1

impart good lubricity to the fiber/braid

Methodology Applied

Scientific EffectLubrication: Lubrication

Implementation Method 2

fill the braid interstices

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentEP2558133B1Coatings for the manufacture and application of polyhydroxyalkanoate medical devices

Publication Date: 2020.01.22 TEPHA INC

AI summary

Biocompatible coatings and spin finishes that can be applied to polyhydroxyalkanoate (PHA) polymers, and medical devices made from PHA polymers, have been developed. The coatings impart good lubricity to PHA polymers, particularly to fibers and braids made from these materials, making the coatings ideal for use on medical devices such as PHA braided sutures. The spin finishes can be applied to PHA fibers to facilitate their manufacture, and also for their conversion to other products, including medical textiles. The spin finishes serve to protect multifilament fiber bundles, and keep them intact following extrusion, and also to impart lubricity to the fiber bundles and monofilament fibers so that they are not damaged in subsequent processing steps particularly in textile processing. The coating reduces tissue drag of, for example, braided sutures.