PHA Suture Coatings for Lower Tissue Drag Without Fiber Damage
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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 PHA braided sutures do not adequately reduce tissue drag without altering the mechanical properties of the fiber.
Innovation Solution
Development of biocompatible coatings and spin finishes for polyhydroxyalkanoate (PHA) polymers, such as polyethylene glycol (PEG) and polyvinyl alcohol, applied to PHA fibers to reduce tissue drag and enhance processing without damaging the fibers, while maintaining the inherent properties of the PHA polymer.
Engineering Contradictions & Design Principles
Engineering 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 properties and shelf life of the fiber may be adversely altered
Solution Approach 1:
The patent applies parameter changes by selecting coatings with specific molecular weight ranges (e.g., PEG with MW 1000-10000 Daltons) and controlling coating weight percentages (0.1-10 wt%) to optimize the balance between tissue drag reduction and maintaining mechanical properties. This resolves the contradiction by adjusting physical parameters of the coating system.
Solution Approach 2:
The patent uses composite material systems combining PHA fibers with biocompatible coating materials (PEG, PVA, polyalkylene oxides) that provide lubricity while maintaining fiber integrity. The composite structure allows the coating to reduce tissue drag without compromising the underlying PHA fiber's mechanical properties.
2Ease of operation
If spin finish is applied to PHA fibers to facilitate processing, then ease of manipulation is improved, but residues may impact biocompatibility and device properties
Solution Approach 1:
The patent employs water-soluble spin finishes that can be easily removed after processing, effectively making them temporary aids rather than permanent components. The spin finish serves its purpose during manufacturing then is eliminated, avoiding long-term biocompatibility issues.
Solution Approach 2:
The spin finish acts as an intermediary substance that facilitates processing operations (spinning, orienting, knitting) but is designed to be completely removable. It mediates between the processing requirements and the final biocompatibility requirements by being present only during manufacturing.
3Ease of operation
If coatings are applied to impart lubricity to PHA braided sutures, then knot security and handling characteristics are improved, but the coating may react with or dissolve the fiber
Solution Approach 1:
The patent applies local quality by using coatings that specifically provide lubricity at the fiber surface interface without penetrating or reacting with the bulk PHA fiber material. The coating's functional properties are localized to where needed (surface lubricity) while leaving the fiber's core mechanical properties intact.
Solution Approach 2:
The patent converts the potential harm of coating-fiber interactions into benefit by selecting coating materials that are chemically incompatible with dissolving or reacting the PHA fiber. The very properties that make these coatings stable and effective (chemical inertness, molecular weight) also protect the fiber from degradation.
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 lower tissue drag forces in PHA braided sutures by at least 10% compared to uncoated braids, ensuring biocompatibility and stability, and can be easily removed without impacting the mechanical properties or shelf life of the medical devices.
Implementation Method 1
These coatings must: impart good lubricity to the fiber/braid
Implementation Method 2
Spin finishes are applied during extrusion of multifilaments to keep the fiber bundle protected and intact, and to impart lubricity to the fiber bundle
Data Source
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.