Bisphosphonate Monolayer Coating for Metallic Implants
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Solution Overview
Problem
Implantable medical devices with metallic substrates face issues with biocompatibility, leading to inflammatory responses, thrombosis, and in-stent restenosis due to chemical and physical irritation, which existing coatings have not adequately addressed.
Innovation Solution
A bisphosphonate-based coating is covalently and directly bonded to the metallic surface of implantable medical devices, forming a monolayer that reduces inflammatory responses and platelet adhesion, promoting endothelialization while maintaining compatibility with platelet-poor plasma and endothelial cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic substrate is used for implantable medical devices to obtain adequate mechanical properties, then mechanical strength is improved, but biocompatibility deteriorates leading to inflammatory responses and immune reactions
Solution Approach 1:
The patent applies composite materials by combining a metallic substrate with a bisphosphonate coating layer. The metallic substrate provides mechanical strength while the bisphosphonate coating provides biocompatibility. This composite structure resolves the contradiction by integrating two materials with complementary properties - the metal substrate maintains structural integrity while the coating layer reduces inflammatory responses and immune reactions through its biocompatible surface chemistry.
2Reliability
If drug-eluting stents are used to prevent in-stent restenosis through inhibition of smooth muscle cell proliferation, then restenosis rate is reduced, but late stent thrombosis increases
Solution Approach 1:
The patent changes the chemical parameters of the stent surface by coating it with bisphosphonate compounds instead of using traditional polymer-based drug delivery systems. This parameter change in surface chemistry provides antiproliferative effects to prevent restenosis while simultaneously reducing thrombogenicity. The bisphosphonate coating modifies the surface properties to be less thrombogenic compared to conventional drug-eluting stents, thus resolving the contradiction between restenosis prevention and thrombosis risk.
3Object-affected harmful factors
If conventional coatings are applied to reduce inflammatory responses, then biocompatibility is improved, but the coatings do not adequately prevent thrombosis and restenosis
Solution Approach 1:
The patent applies universality by designing a bisphosphonate coating that performs multiple functions simultaneously: it reduces inflammatory responses, prevents thrombosis, and inhibits restenosis. The bisphosphonate compound acts as a multi-functional agent that addresses all three major complications (inflammation, thrombosis, and restenosis) through its unique mechanism of action on osteoclasts and smooth muscle cells, eliminating the need for separate coatings for each function and providing comprehensive biocompatibility improvement.
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 bisphosphonate coating significantly decreases the risk of thrombosis and in-stent restenosis by reducing chronic inflammatory reactions and platelet aggregation, while supporting rapid endothelial cell growth and maintaining biocompatibility.
Implementation Method 1
a bisphosphonate-based coating covalently and directly bonded to a surface of the metallic part
Implementation Method 2
decreases the risk of thrombosis and in-stent restenosis by reducing chronic inflammatory reactions and platelet aggregation
Data Source
Figure 1~4
AI summary
An implantable medical device comprising (a) a metallic substrate and (b) a bisphosphonate wherein both phosphorus atoms contained in the bisphosphonate are covalently attached to a same carbon atom. The bisphosphonate continuously coats the external surface of the metallic substrate as monolayer and as outermost layer. At least one phosphonate moiety of the bisphosphonate is covalently and directly bonded to the external surface of the metallic substrate and/or covalently bonded to another molecule of the bisphosphonate in the coating.