Citric Acid Stent Coating for Thrombosis and Endothelialisation
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Solution Overview
Problem
Existing medical devices cause thrombosis and impaired endothelialisation due to foreign body reactions, with current coatings being time-limited and having poor biocompatibility, and bioactive compounds either lacking mechanical properties or increasing device dimensions.
Innovation Solution
A non-porous layer of carboxylic acid or its derivative, such as citric acid, is applied as an outermost coating on medical devices to mask the underlying structure, promoting endothelialisation and reducing thrombosis by directly contacting the vessel wall, without using polymers or time-release agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer carrier matrix is used to elute antithrombogenic agents, then the device provides time-limited thromboprotection, but the carrier matrix exhibits poor biocompatibility causing further physiological complications
Solution Approach 1:
The patent extracts and eliminates the polymer carrier matrix from the coating system, using only the antithrombogenic agent (heparin or heparin sulphate) directly in a non-porous form. This removes the source of poor biocompatibility while maintaining the thromboprotective function through direct drug delivery without a degradable polymer scaffold.
Solution Approach 2:
The patent changes the physical state and composition parameters of the coating by formulating a non-porous matrix containing only the antithrombogenic agent without polymer carriers. This parameter change eliminates the biocompatibility issues associated with polymer degradation products while maintaining controlled drug delivery through the non-porous structure.
2Reliability
If drug-eluting stents are used to interrupt the healing response, then thrombosis is reduced, but the vascular wall cannot heal optimally and the device remains exposed longer
Solution Approach 1:
The patent applies different functional qualities to different aspects of the coating: the non-porous structure provides immediate thromboprotection, while the absence of cytotoxic polymer carriers and the inclusion of bioactive compounds create a locally favorable environment for endothelial cell adhesion and proliferation, enabling simultaneous thrombosis reduction and enhanced healing.
Solution Approach 2:
The patent creates a composite coating system that integrates antithrombogenic agents (heparin/heparin sulphate) with bioactive compounds that promote endothelialisation, all within a non-porous matrix structure. This composite approach allows multiple functions (thromboprotection + enhanced healing) to be achieved in a single coating layer without the drawbacks of polymer carriers.
3Object-affected harmful factors
If materials with advantageous thrombogenic or endothelialisation properties are used, then biocompatibility improves, but mechanical properties deteriorate or device dimensions increase
Solution Approach 1:
The patent employs a thin-film non-porous coating structure that provides the necessary biocompatible surface properties for thromboprotection and endothelialisation while maintaining the underlying device's mechanical integrity. The thin film approach ensures that the coating does not significantly alter device dimensions or compromise structural strength.
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 carboxylic acid coating enhances endothelialisation and reduces thrombosis by providing a biocompatible, stable surface that adheres well to the device, maintaining mechanical integrity and avoiding unnecessary carrier substances in the body.
Implementation Method 1
a non-porous layer of carboxylic acid or its derivative, such as citric acid, is applied as an outermost coating on medical devices to mask the underlying structure
Data Source
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AI summary
A medical device such as a stent (10) or medical balloon (40) is at least partially coated with a carboxylic acid layer in order to enhance biocompatibility, reduce thrombogenesis and increase endothelialisation. The coating is preferably of citric acid in non-crosslinked form and preferably non-porous so as to mask the underlying structure of the medical device. The acid coating forms an outer surface of at least a part of the medical device, that is has no other layer or material overlying it, save for in some embodiments a partial coating of a bioactive material.