ABA Tri-block Copolymer for Bioresorbable Vascular Implants
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Solution Overview
Problem
Conventional polymeric materials used in medical implants, such as vessel closure devices and stents, face challenges with mechanical strength, flexibility, and degradation rates, leading to issues like stent dislodgment, restenosis, and inadequate hemostasis, particularly in vascular procedures.
Innovation Solution
Development of ABA tri-block copolymers with a crystalline A block providing mechanical strength and an amorphous B block offering elasticity and flexibility, allowing for rapid degradation, making them suitable for bioresorbable and biocompatible medical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymeric materials are used in medical implants, then mechanical strength is maintained, but degradation rate is too slow and flexibility is insufficient
Solution Approach 1:
The patent employs ABA tri-block copolymer composite materials where block A provides mechanical strength through crystalline structure and block B provides rapid degradation through amorphous structure. This composite polymeric material resolves the contradiction by combining materials with opposing properties in a single integrated system, allowing the implant to maintain strength when needed while degrading at a controlled rapid rate.
Solution Approach 2:
The patent applies local quality by creating distinct blocks within the copolymer where block A (crystalline) is localized to provide strength in specific regions, while block B (amorphous) is localized to provide degradation capability in other regions. This spatial differentiation of material properties within the same polymer chain allows simultaneous achievement of strength and rapid degradation.
2Strength
If conventional polymeric materials are used in medical implants, then mechanical strength is maintained, but flexibility is insufficient
Solution Approach 1:
The ABA tri-block copolymer functions as a composite material where the crystalline block A contributes mechanical strength while the amorphous block B contributes flexibility and elasticity. This composite structure at the molecular level allows the material to exhibit both strength and flexibility simultaneously, resolving the contradiction between these two mechanical properties.
Solution Approach 2:
The patent implements local quality by creating distinct segments within the polymer chain where block A provides localized strength and block B provides localized flexibility. This segmentation allows different regions of the same material to exhibit different mechanical properties, enabling the overall material to be both strong and flexible.
3Reliability
If vessel closure devices are used after percutaneous procedures, then hemostasis is achieved, but stent dislodgment and restenosis may occur
Solution Approach 1:
The ABA tri-block copolymer creates a composite material where the crystalline blocks provide structural integrity for reliable hemostasis while the amorphous blocks enable controlled degradation that prevents long-term complications like restenosis. The material degrades after serving its hemostatic function, eliminating the harmful effects associated with permanent implants.
Solution Approach 2:
The patent applies parameter changes by controlling the degradation rate of the polymeric material through the proportion and composition of blocks A and B. The material transitions from a stable state (providing hemostasis) to a degrading state (preventing restenosis) over time, with degradation parameters tuned to match the therapeutic timeline.
4Reliability
If stents are used to maintain vessel patency, then vessel support is provided, but mechanical strength and flexibility balance is inadequate
Solution Approach 1:
The ABA tri-block copolymer functions as a composite material where block A (crystalline) provides the mechanical strength needed for vessel support and block B (amorphous) provides the flexibility needed for vessel conformability. This composite structure allows the stent to maintain vessel patency while having appropriate mechanical properties for safe deployment and long-term function.
Data Source
AI summary
A block copolymer comprises an A block and a B block. The A block provides mechanical strength while the B block provides elasticity to the polymeric material. The block copolymer may be an ABA tri-block copolymer. The A block may include one or more of polyglycolide (PGA), polylactic acid (PLA), or copolymer thereof. The B block may include a random copolymer of (i) glycolide (GA) and/or lactide (LA), (ii) trimethylene carbonate (TMC), and (iii) ε-caprolactone (CL). The block copolymer may cover an implantable device which may be used in delivering immediate hemostasis at a puncture site in a wall of a blood vessel.