PLA-PCL Copolymer Scaffolds for High Radial Strength
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Solution Overview
Problem
Current bioresorbable polymer stents face challenges in achieving high radial strength and resistance to fracture while maintaining a thin strut thickness, particularly in peripheral vascular applications where they are subjected to various mechanical forces, leading to potential chronic recoil and strut fractures before intended bioresorption.
Innovation Solution
A bioresorbable polymer scaffold composed of a combination of polylactide (PLA) and polycaprolactone (PCL) with a high molecular weight, specifically a blend or copolymer formulation that includes a random or block copolymer structure, processed to enhance crystallinity and radial strength, achieving strut thicknesses less than 120 microns and maintaining radial strength of at least 350 mm Hg when expanded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If bioresorbable polymer stents use thin strut thickness to improve deliverability and reduce chronic recoil, then radial strength and resistance to fracture deteriorate
Solution Approach 1:
The patent employs a composite polymer system combining polylactide (PLA) and polycaprolactone (PCL) to achieve both thin strut dimensions and high radial strength. The PLA-PCL copolymer or blend formulation creates a material with optimized mechanical properties that simultaneously provides fracture resistance and enables strut thickness below 120 microns while maintaining radial strength above 350 mm Hg.
Solution Approach 2:
The patent utilizes high molecular weight polymers (number average molecular weight greater than 110 kDa) to enhance the mechanical strength of thin struts. By changing the molecular weight parameter and controlling crystallinity through processing, the material achieves sufficient fracture resistance and radial strength despite the reduced strut thickness, resolving the contradiction between thin dimensions and structural strength.
2Strength
If bioresorbable polymer stents increase radial strength to withstand mechanical forces, then fracture resistance improves but deliverability and flexibility deteriorate
Solution Approach 1:
The patent achieves high radial strength (at least 350 mm Hg) while maintaining deliverability by changing key material parameters: using high molecular weight polymers (Mn > 110 kDa) and controlling crystallinity through specific processing methods. These parameter changes enable the polymer to be sufficiently strong when expanded yet flexible enough for crimping and delivery through catheters.
Solution Approach 2:
The PLA-PCL composite material system provides a balance between strength and flexibility. The copolymer or blend formulation creates a material that can be crimped for delivery and then expanded to provide adequate radial support, resolving the contradiction between deliverability and radial strength.
3Strength
If bioresorbable polymer stents maintain high molecular weight for strength, then radial strength improves but processability and manufacturing difficulty worsen
Solution Approach 1:
The patent combines high molecular weight polylactide and polycaprolactone in specific ratios to create a composite material that maintains high strength (radial strength ≥ 350 mm Hg) while improving processability. The PCL component facilitates processing through controlled crystallization, enabling manufacturing of high-performance scaffolds with thin struts despite using high molecular weight polymers.
Solution Approach 2:
The patent controls the crystallinity of the polymer through processing parameters to achieve the desired balance between strength and processability. By adjusting crystallinity during manufacturing, the high molecular weight polymer becomes more manageable while retaining its strength advantages, resolving the manufacturing difficulty.
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 scaffold provides sufficient radial strength and fracture resistance, allowing for effective mechanical support and bioresorption, reducing the risk of chronic recoil and strut fractures, while maintaining a low profile for improved deliverability and minimizing long-term damage in peripheral vascular applications.
Implementation Method 1
bioresorbable polymer scaffold comprising a polymer combination including a polylactide (PLA) polymer and polycaprolactone (PCL)
Implementation Method 2
processed to enhance crystallinity and radial strength
Data Source
AI summary
Bioresorbable polymer vascular scaffolds made of combinations of polylactide and polycaprolactone having a high molecular weight polymer, thin struts in a selected range and sufficient radial strength to support a vessel upon deployment. The scaffolds have degradation behavior of molecular weight, radial strength, and mass that are conducive to healing of a vessel including providing patency to a vessel, reduction of radial strength, breaking up, and resorbing to allow return of the vessel to a natural state.