Biodegradable Stent Coating with Plasticizer for Delamination Prevention
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Solution Overview
Problem
Conventional drug-containing stent coatings face issues with delamination during stent expansion, limiting their ability to maintain mechanical integrity and ensure controlled drug release over a long period.
Innovation Solution
A non-biodegradable stent coated with a biodegradable polymer layer and a plasticizer, which eliminates the need for a primer coating, allowing for a thicker coating and higher drug loading while maintaining mechanical integrity during storage and balloon expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primer coating is used to prevent delamination, then mechanical integrity is improved, but coating thickness increases and biodegradability is compromised
Solution Approach 1:
The patent removes the primer coating layer from the coating structure, extracting the problematic non-biodegradable component while maintaining the essential function of preventing delamination through the biodegradable polymer coating alone
Solution Approach 2:
The patent changes the chemical composition parameters of the coating by using biodegradable polymers with specific properties (elastic modulus, glass transition temperature) that allow the coating to maintain mechanical integrity without requiring a primer layer
2Reliability
If a primer coating is used to prevent delamination, then coating adhesion is improved, but drug loading capacity decreases
Solution Approach 1:
The patent extracts the primer coating layer that was preventing direct drug loading onto the stent, allowing the biodegradable polymer coating to serve both as adhesive layer and drug carrier simultaneously
Solution Approach 2:
The patent merges the functions of the primer coating and drug-containing coating into a single integrated biodegradable polymer coating layer that provides both adhesion and drug loading capabilities
3Duration of action of moving object
If coating thickness is increased to sustain long-term drug release, then drug release duration is improved, but mechanical integrity deteriorates due to delamination
Solution Approach 1:
The patent changes the physical and chemical parameters of the polymer coating (compliance, glass transition temperature, elastic modulus) to match the stent substrate, enabling thicker coatings to maintain mechanical integrity and prevent delamination
Solution Approach 2:
The patent uses composite biodegradable polymer formulations combining different polymers (PLGA, PCL, PLA) with complementary properties to achieve both adequate thickness for long-term drug release and mechanical compliance to prevent delamination
4Object-generated harmful factors
If biodegradable polymer coating is used without primer, then biodegradability is improved, but mechanical integrity worsens due to delamination
Solution Approach 1:
The patent optimizes the physical and chemical parameters of the biodegradable polymer coating (glass transition temperature, elastic modulus, compliance) to match the stent substrate, enabling direct coating without primer while maintaining mechanical integrity
Solution Approach 2:
The patent employs composite biodegradable polymer formulations that combine materials with different degradation rates and mechanical properties to ensure both biodegradability and mechanical stability during the stent's functional life
Data Source
AI summary
The present invention relates to the field of non-biodegradable stents, and therein to non-biodegradable stents coated with at least one layer of a biodegradable polymer which maintains mechanical integrity of the coating both in storage and upon balloon expansion and which can optionally release drugs. The at least one polymer layer comprises a biodegradable polymer and a plasticizer. The present invention also relates to a manufacturing method of such a non-biodegradable stent.