Electro-grafted Biodegradable Primer for Drug Eluting Stents

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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 cracking and delamination.

Innovation Solution

A drug eluting stent with an electro-grafted biodegradable primer coating to enhance adhesion and mechanical integrity, allowing for complete drug release and promoting endothelial cell recolonization by using a biodegradable polymer coating that disappears after a few weeks, reducing the risk of thrombosis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If a biostable polymer coating is used to release drug, then the coating provides long-term drug delivery, but the coating cannot be completely removed and hinders endothelial cell recolonization

Engineering Contradiction:

Improvedrug release durationVSAvoidhindrance to endothelial cell recolonization

Core Design Contradiction:

Duration of action of moving objectVSObject-generated harmful factors

Solution Approach 1:

The coating is divided into two distinct layers: a biostable primer layer that remains permanently on the stent to provide structural integrity and drug delivery capability, and a biodegradable topcoat layer that degrades completely after drug release. This segmentation allows each layer to fulfill its specific function without the drawbacks of a single-layer system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The biodegradable topcoat layer is designed to be temporarily present and then completely degraded and discarded by the body after serving its purpose of drug delivery and protecting the primer layer. This eliminates the long-term presence of polymer that hinders endothelial cell recolonization, while the biostable primer layer remains to provide continued therapeutic effect.

Inventive Principle:

Principle #34Discarding and recovering

2Quantity of substance

If a thick polymer coating is used to host drug, then more drug can be loaded, but the coating becomes prone to cracking and delamination

Engineering Contradiction:

Improvedrug loading capacityVSAvoidcoating integrity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The drug-hosting function is divided between two layers: the biostable primer layer provides a stable foundation and hosts some drug, while the biodegradable topcoat layer provides additional drug loading capacity. This segmentation distributes the mechanical stress and prevents the formation of cracks that would occur in a single thick polymer layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coating system uses a composite structure combining biostable and biodegradable polymer materials with different mechanical and degradation properties. This composite approach optimizes both drug loading capacity and coating integrity by leveraging the strengths of each material type.

Inventive Principle:

Principle #40Composite materials

3Strength

If a biostable polymer layer remains on the stent, then the coating maintains mechanical integrity long-term, but it prevents complete drug release and causes late thrombosis

Engineering Contradiction:

Improvecoating mechanical integrityVSAvoidlate thrombosis

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The coating is segmented into a biostable primer layer that maintains long-term mechanical integrity and a biodegradable topcoat layer that degrades completely. This segmentation allows the biostable layer to provide structural support while the biodegradable layer ensures complete drug release and eliminates the source of late thrombosis.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the coating have different properties: the primer layer near the stent surface maintains permanent integrity for structural support, while the topcoat layer has biodegradable properties to enable complete drug release. This local differentiation of material properties resolves the contradiction between long-term integrity and complete drug release.

Inventive Principle:

Principle #3Local quality

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 electro-grafted biodegradable primer coating ensures complete drug release, improved endothelial recolonization, and reduced thrombosis risk, enabling the discontinuation of anti-platelet therapy sooner after stent implantation while maintaining mechanical integrity.

Implementation Method 1

a electro-grafted coating disposed on the stent framework

Methodology Applied

Scientific EffectElectro-grafting: Electrodeposition

Implementation Method 2

a biodegradable polymer coating hosting a drug disposed on the electro-grafted coating

Methodology Applied

Scientific EffectBiodegradation: Decomposition (biological)

Data Source

PatentUS9884142B2Drug eluting stent with a biodegradable release layer attached with an electro-grafted primer coating

Publication Date: 2018.02.06 ALCHIMEDICS

AI summary

The present invention provides a drug eluting stent including a metallic stent framework, an electro-grafted primer coating disposed on the stent framework; and a biodegradable polymer coating hosting a drug disposed on the electro-grafted primer coating and a method of manufacturing said biodegradable drug eluting stent.