PHA Fiber Coatings and Spin Finishes for Low-Drag Sutures

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Solution Overview

Problem

There is a need for absorbable braided sutures with improved performance, specifically high initial tensile strength, prolonged strength retention in vivo, good knot security, low tissue drag, and biocompatibility, while existing coatings for polyhydroxyalkanoate (PHA) sutures do not adequately reduce tissue drag without compromising the mechanical and thermal properties of the fiber.

Innovation Solution

Development of biocompatible coatings and spin finishes for PHA polymers and fibers, including polymers or oligomers of ethylene oxide, propylene oxide, and polyvinyl alcohol, which are applied to reduce tissue drag and enhance processing without damaging the fibers, and can be easily removed to ensure cytotoxicity safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

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

Engineering Contradiction:

Improvetissue dragVSAvoidmechanical and thermal properties of fiber

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The coating is applied selectively to the surface of the PHA braid, providing lubricity where needed (at the tissue interface) while leaving the bulk fiber properties intact. This localized application reduces tissue drag without compromising the overall mechanical strength and thermal properties of the suture fiber.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coating acts as an intermediary layer between the PHA braid and the tissue, reducing direct interaction and friction. This intermediate layer provides the lubricity needed to reduce tissue drag while the underlying fiber maintains its structural integrity and mechanical properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If coatings are applied to PHA fibers to impart 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 coating formulation is specifically designed with parameters (chemical composition, molecular weight, crosslinking density) that ensure compatibility with PHA fibers. The coating is selected or engineered to have chemical stability with respect to PHA, preventing reactions or dissolution while maintaining the desired lubricity properties.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If spin finish is applied to PHA fibers to facilitate processing, then ease of manipulation is improved, but residues may be difficult to remove or may be cytotoxic

Engineering Contradiction:

Improveease of manipulation during processingVSAvoidcytotoxicity of residues

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The spin finish is designed as a temporary, removable substance that performs its function during processing and then can be completely or largely removed before implantation. Like a disposable tool, it serves its purpose and is discarded, ensuring no harmful residues remain in the final medical device.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The spin finish is extracted or removed from the fiber after processing is complete. This extraction step separates the temporary processing aid from the final product, ensuring that no cytotoxic residues remain on the implantable suture while the fiber retains the processing benefits.

Inventive Principle:

Principle #2Taking out (Extraction)

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 significantly reduce tissue drag by at least 10% and maintain the mechanical properties of PHA fibers, ensuring biocompatibility and prolonged strength retention, making them suitable for medical applications such as sutures and textiles.

Implementation Method 1

impart good lubricity to the fiber/braid

Methodology Applied

Scientific EffectLubrication: Lubrication

Implementation Method 2

impart lubricity to the fiber bundle so that it may be manipulated in subsequent processing steps without damaging the fiber

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS9326841B2Coatings for the manufacture and application of polyhydroxyalkanoate medical devices

Publication Date: 2016.05.03 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.