Biodegradable Stent Coating Integrity After Sterilization
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Solution Overview
Problem
Existing drug delivery stents face challenges with compromised coating integrity due to ethylene oxide sterilization and crimping processes, leading to potential adhesion to delivery balloons and incomplete degradation, which can result in thrombosis and restenosis.
Innovation Solution
A biodegradable implantable device with a coating comprising a terpolymer layer and a primer layer, where the terpolymer has a glass transition temperature less than 37°C, maintaining integrity after sterilization and providing a controlled release of bioactive agents, with a degradation rate ensuring 80% mass loss within 6 months.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an amorphous bioabsorbable polymer is used for coating a stent, then the coating can be applied, but the coating integrity is compromised during ethylene oxide sterilization and crimping processes
Solution Approach 1:
The invention uses a composite polymer system consisting of poly(glycolide-co-caprolactone) copolymer combined with poly(D,L-lactide) or poly(L-lactide) homopolymer. This composite approach allows the coating to maintain integrity during sterilization and crimping while remaining bioabsorbable, resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The invention modifies the polymer composition parameters by incorporating specific ratios of glycolide (30-70 mol%), caprolactone (10-40 mol%), and lactide (10-40 mol%) to achieve the desired balance between coating applicability and integrity maintenance under processing conditions.
2Stability of the object's composition
If the coating is designed to degrade completely, then bioabsorbability is achieved, but coating integrity may be compromised leading to thrombosis and restenosis
Solution Approach 1:
The coating is designed to maintain its structural integrity and protective function during the critical early period after implantation, then gradually degrade over time. This preliminary stability prevents thrombosis and restenosis, while the controlled degradation achieves complete bioabsorbability, resolving the contradiction between stability and harmful effects.
Solution Approach 2:
The invention controls the degradation rate by adjusting the polymer composition parameters, ensuring the coating maintains stability when needed and degrades appropriately over time to eliminate harmful effects while achieving complete bioabsorbability.
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 coating maintains mechanical integrity and ensures complete degradation, reducing the risk of thrombosis and restenosis by providing a controlled release of bioactive agents, effectively addressing the challenges of coating integrity and degradation.
Implementation Method 1
providing a controlled release of bioactive agents
Implementation Method 2
degradation rate ensuring 80% mass loss within 6 months
Implementation Method 3
maintains integrity after sterilization
Implementation Method 4
maintains integrity after sterilization
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention provides a coating comprising a reservoir layer comprising a terpolymer comprising caprolactone and glycolide and a primer layer comprising an amorphous polymer on an implantable device and methods of making and using the same.