Medical Device Coating Adhesion via Intermediary Copolymer
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Solution Overview
Problem
Current medical devices with polymeric coatings on metallic substrates face issues with adhesion, particularly on the luminal surface, which can interfere with endothelial cell growth and require minimizing polymer content to avoid biological responses.
Innovation Solution
A medical device comprising a metallic substrate with a polymeric region that includes a block copolymer with high and low Tg monomers, an adhesion promoting copolymer that bonds with the substrate, and a therapeutic agent, optionally with a release-affecting polymer to tailor drug release profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymeric coating is applied to the metallic substrate to serve as a drug reservoir, then therapeutic agent release is achieved, but adhesion to the substrate is poor
Solution Approach 1:
The patent introduces an adhesion promoting copolymer as an intermediary layer between the metallic substrate and the block copolymer drug reservoir. This copolymer contains monomers that form covalent or non-covalent bonds with the metallic substrate, creating a strong adhesive interface while remaining compatible with the block copolymer matrix, thus resolving the adhesion problem without compromising coating application.
Solution Approach 2:
The patent creates a composite polymeric coating system consisting of multiple components: the block copolymer (providing drug reservoir function), the adhesion promoting copolymer (providing substrate bonding), and optionally a release-affecting polymer. This composite structure allows each component to perform its specific function, achieving both strong adhesion and effective drug release.
2Object-affected harmful factors
If polymer content is minimized to reduce biological responses, then biocompatibility is improved, but drug delivery effectiveness is compromised
Solution Approach 1:
The patent applies different polymer compositions to different regions or functions within the coating. The adhesion promoting copolymer is used specifically at the substrate interface where bonding is critical, while the block copolymer is used in the bulk where drug delivery occurs. This local differentiation allows minimization of total polymer content while maintaining both biocompatibility and drug delivery effectiveness.
Solution Approach 2:
The patent optimizes parameters such as copolymer composition, molecular weight, and layer thickness to achieve the minimum effective polymer content. By carefully controlling these parameters, the coating provides sufficient drug delivery capacity while minimizing the total polymer quantity that could trigger biological responses.
3Object-affected harmful factors
If a polymeric layer is present on the luminal surface to promote biocompatibility, then endothelial cell growth is supported, but the layer may retard healthy endothelial cell growth
Solution Approach 1:
The patent extracts or removes the polymeric coating from the luminal surface, applying it only to the abluminal surface where it is needed for drug delivery and biocompatibility. This selective placement eliminates the harmful effect of the polymer layer interfering with luminal endothelial cell growth while maintaining the beneficial effects on the abluminal surface.
Solution Approach 2:
The patent applies different properties to different surfaces of the stent. The luminal surface is left without polymer coating to support endothelialization, while the abluminal surface receives the polymer-coated drug reservoir for biocompatibility and drug delivery. This local differentiation resolves the contradiction between biocompatibility and endothelial cell growth promotion.
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 solution enhances adhesion of therapeutic-agent-releasing layers to metallic substrates, improving biocompatibility and minimizing polymer content, thereby reducing potential biological responses while maintaining effective drug delivery.
Implementation Method 1
a first monomer that covalently or non-covalently bonds with the metallic substrate
Implementation Method 2
a first monomer that covalently or non-covalently bonds with the metallic substrate
Implementation Method 3
SIBS tends to phase separate, with the elastomeric blocks aggregating to form elastomeric phase domains and the hard blocks aggregating to form hard phase domains
Implementation Method 4
a polymeric coating that serves as a reservoir for one or more therapeutic agents
Implementation Method 5
therapeutic agents, including, for example, antiproliferative agents such as paclitaxel
Data Source
AI summary
According to an aspect of the present invention, a medical device is provided which comprises a metallic substrate and polymeric region disposed over and in contact with the metallic substrate. The polymeric region comprises (a) a block copolymer that comprises (i) a hard polymer block that comprises a high Tg monomer and (ii) a soft polymer block that comprises a low Tg monomer, (b) an adhesion promoting copolymer that comprises (i) a first monomer that covalently or non-covalently bonds with the metallic substrate and (ii) a second monomer that is compatible with the low Tg monomer and/or the high Tg monomer and (c) a therapeutic agent. The polymeric region may further comprise an optional polymer that is used to tailor the release rate of the therapeutic agent.