Biodegradable Stent Coating via Electro-Grafted Primer

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Solution Overview

Problem

Existing drug eluting stents face challenges with incomplete drug release, poor coating integrity leading to restenosis and late thrombosis due to biostable polymer layers that hinder endothelial cell recolonization and are prone to delamination, resulting in prolonged anti-thrombotic therapy requirements.

Innovation Solution

A drug eluting stent with a biodegradable polymer coating and an electro-grafted primer coating to ensure complete drug release, improve mechanical integrity, and promote endothelial cell recolonization, using a biodegradable topcoat layer and electro-grafted p-BuMA as an adhesion primer to prevent cracking and delamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a biostable polymer coating is used to release drugs, then drug delivery capability is improved, but the coating prevents complete drug release and hinders endothelial cell recolonization

Engineering Contradiction:

Improvedrug release completenessVSAvoidendothelial cell recolonization

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The coating is segmented into two functional layers: a biodegradable release matrix that completely degrades to release 100% of the drug, and a biostable primer coating that remains to promote endothelial cell recolonization. This segmentation resolves the contradiction by allowing the release matrix to fully degrade for complete drug delivery while the primer layer provides a reliable surface for cell recolonization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the coating have different properties: the release matrix is designed to be biodegradable for complete drug release, while the primer coating is biostable to support endothelial cell attachment and recolonization. This local differentiation of material properties resolves the contradiction between complete drug release and reliable cell recolonization.

Inventive Principle:

Principle #3Local quality

2Reliability

If a biostable polymer layer is used to prevent restenosis, then short-term anti-proliferative effect is improved, but long-term thrombosis risk increases due to prolonged drug presence

Engineering Contradiction:

Improverestenosis preventionVSAvoidlate thrombosis risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The release matrix is designed to be biodegradable rather than static and permanent. It dynamically degrades over time, releasing the drug as it breaks down and completely disappearing after drug release. This dynamic behavior ensures the drug is available when needed for restenosis prevention but disappears afterward to eliminate the source of late thrombosis risk.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The biodegradable release matrix is discarded after completing its drug delivery function. As it degrades and disappears, it releases 100% of the drug and then is eliminated from the system, preventing the prolonged drug presence that causes late thrombosis while maintaining effective restenosis prevention during the critical period.

Inventive Principle:

Principle #34Discarding and recovering

3Quantity of substance

If a biodegradable release matrix is used to enable complete drug release, then drug delivery is improved, but coating mechanical integrity deteriorates due to delamination and cracking

Engineering Contradiction:

Improvedrug release completenessVSAvoidcoating mechanical integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The biostable primer coating is applied first to the stent surface before applying the biodegradable release matrix. This preliminary action creates a strong adhesive foundation that prevents delamination and cracking of the subsequent release matrix during mechanical deformation, allowing the release matrix to maintain complete drug release capability without compromising coating integrity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coating system uses composite materials combining a biostable primer coating with a biodegradable release matrix. The biostable primer provides mechanical strength and adhesion to prevent cracking and delamination, while the biodegradable release matrix enables complete drug release. This composite structure resolves the contradiction between mechanical integrity and complete drug release.

Inventive Principle:

Principle #40Composite materials

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 enables complete drug release, improved endothelial recolonization, reduced inflammation, and the potential for early discontinuation of anti-thrombotic therapy by ensuring the biodegradable layer disappears within weeks, thus addressing restenosis and late thrombosis issues.

Implementation Method 1

electro-grafted primer coating to ensure complete drug release, improve mechanical integrity, and promote endothelial cell recolonization

Methodology Applied

Scientific EffectElectro-grafting: Electrodeposition

Data Source

PatentEP2716307B1Drug eluting stent with a biodegradable release layer attached with an electro-grafted primer coating

Publication Date: 2022.08.03 ALCHIMEDICS

Figure 1(A)~1(B)
Figure 2

AI summary

A drug eluting preventing restenosis, avoiding thrombosis and allowing for early proliferation and migration of endothelial cells is disclosed. The stent has a surface with a layer that promotes proliferation and adhesion of the endothelial cells and a drug hosting biodegradable polymer coating covering the surface which is degraded to completely release the drug.