Biodegradable Polyurethane Coating for Stent Thrombogenicity
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Solution Overview
Problem
Current drug-eluting vascular stents face challenges with thrombogenicity, leading to late stent thrombosis due to non-degradable polymeric coatings that fail to become endothelialized and present a thrombogenic surface to blood, resulting in persistent thrombotic complications.
Innovation Solution
A biodegradable polymer with anti-thrombogenic groups, such as zwitterionic groups like phosphorylcholine, is integrated into the coating, which includes hydrolytically labile bonds and functional groups that react with the stent surface, reducing thrombogenicity and enabling controlled release of anti-proliferative drugs like paclitaxel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-degradable polymeric coatings are used on vascular stents, then drug reservoir function is maintained, but thrombogenicity increases leading to late stent thrombosis
Solution Approach 1:
The patent changes the degradation parameter of the polymer coating from non-degradable to biodegradable, specifically using polyesters with ester bonds that hydrolyze in vivo. This allows the coating to maintain drug reservoir function initially, then gradually degrade to reduce thrombogenicity and allow endothelialization over time, resolving the contradiction between maintaining drug delivery and reducing thrombotic complications.
Solution Approach 2:
The patent creates a composite coating system combining biodegradable polyester matrix with embedded anti-proliferative drugs. The composite structure allows the polymer to provide initial drug reservoir function while its biodegradable nature enables gradual breakdown into non-thrombogenic byproducts, simultaneously addressing both drug delivery and thrombogenicity issues.
2Object-affected harmful factors
If biodegradable coatings are used on vascular stents, then thrombogenicity is reduced, but evidence of marked reduction in thrombotic complication rates is limited
Solution Approach 1:
The patent ensures continuous anti-thrombogenic action through the gradual hydrolysis of ester bonds in the polyester coating. As the coating degrades continuously in vivo, it maintains a non-thrombogenic surface throughout the degradation process, providing sustained protection against thrombotic complications rather than a single-time effect.
Solution Approach 2:
The patent uses water as an intermediary that penetrates the polyester coating and triggers hydrolytic degradation of ester bonds. This intermediary mechanism enables controlled breakdown of the coating into non-thrombogenic fragments, mediating the transition from a potentially thrombogenic state to a non-thrombogenic state over time.
3Object-affected harmful factors
If anti-thrombogenic groups are incorporated into biodegradable polymer, then non-thrombogenic surface is achieved, but polymer synthesis complexity increases
Solution Approach 1:
The patent merges the anti-thrombogenic functionality directly into the polyester backbone structure by incorporating hydrophilic groups such as carboxyl, hydroxyl, or amide groups within the repeating units. This integration eliminates the need for separate surface modification steps, combining structural integrity, biodegradability, and non-thrombogenicity in a single polymer synthesis process.
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 biodegradable polymer coating significantly decreases platelet deposition and thrombogenicity, providing a non-thrombogenic surface that reduces inflammatory responses and intimal hyperplasia, while effectively releasing anti-proliferative drugs to inhibit vascular smooth muscle cell proliferation.
Implementation Method 1
The biodegradable groups may, for example, include at least one hydrolytically labile bond
Implementation Method 2
the anti-thrombogenic groups are zwitterionic groups. The zwitterionic group may for example include at least one of a phosphorylcholine group
Data Source
AI summary
A method of forming an implantable article includes providing a biodegradable polymer including anti-thrombogenic groups along the length of the biodegradable polymer, biodegradable groups in the backbone of the biodegradable polymer and a plurality of functional groups adapted to react with reactive functional groups on a surface of the implantable article, and reacting at least a portion of the plurality of functional groups with the reactive functional groups on the surface of the implantable article.