Biodegradable Vascular Embolization Particles with Shape Recovery
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Solution Overview
Problem
Existing vascular embolization materials face issues with irreversible deformation and lack of flexibility, leading to clogging and inadequate delivery through catheters, which hampers effective embolization of blood vessels.
Innovation Solution
A biodegradable particle composed of a block copolymer with specific structural and molecular weight characteristics, including a biodegradable copolymer, a water-soluble polymer, and a polyvalent compound, which allows for enhanced flexibility and shape recovery after passing through a catheter, reducing aggregation and clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer particles are used for embolization, then embolization effect is achieved, but irreversible deformation and lack of flexibility occur causing clogging
Solution Approach 1:
The invention uses a block copolymer composite structure consisting of a biodegradable copolymer block (providing embolization functionality) and a flexible polymer block (providing elasticity and shape recovery). This composite structure resolves the contradiction by combining materials with complementary properties to achieve both reliable embolization and flexible catheter delivery.
Solution Approach 2:
The invention changes the physical and chemical parameters of the polymer particles by controlling the glass transition temperatures of the constituent blocks. The biodegradable copolymer block has Tg ≥ 40°C for structural integrity, while the flexible block has Tg ≤ -40°C for elasticity. This parameter optimization enables particles to maintain shape for embolization while flexing during catheter passage.
2Productivity
If polymer particles are delivered through microcatheter, then embolization delivery is achieved, but aggregation and clogging occur
Solution Approach 1:
The flexible polymer block forms a soft shell or surface layer around the biodegradable copolymer core. This flexible shell prevents particle aggregation by reducing inter-particle adhesion and enables the particles to deform elastically during catheter passage, preventing clogging while maintaining delivery efficiency.
Solution Approach 2:
The flexible polymer block acts as an intermediary between the biodegradable copolymer core and the aqueous environment. It provides a hydrophilic surface that prevents aggregation through steric stabilization and reduces interaction with catheter walls, thereby preventing clogging during delivery.
3Ease of operation
If particle flexibility is increased, then catheter passage is improved, but shape recovery ability decreases
Solution Approach 1:
The invention segments the particle into distinct functional blocks: a rigid biodegradable copolymer block (≥40°C Tg) that maintains spherical shape and provides embolization function, and a flexible polymer block (≤-40°C Tg) that enables deformation during catheter passage. The segmented structure allows each block to perform its specific function independently, resolving the contradiction between flexibility and shape recovery.
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 biodegradable particles exhibit improved flexibility and shape recovery, enabling effective embolization of blood vessels with minimal material usage and reduced clogging, ensuring efficient delivery and embolization.
Implementation Method 1
the particles have problems such as insufficient flexibility of the particles themselves, occurrence of aggregation to cause clogging of the catheter, and irreversible deformation of the polymer particles before they reach the target site
Implementation Method 2
a block copolymer produced by copolymerization of: a biodegradable copolymer having a structure composed of at least hydroxycarboxylic acid a1 and hydroxycarboxylic acid a2
Data Source
AI summary
The present invention aims to provide a biodegradable vascular embolization material that is less likely to coagulate and has an improved flexibility, and whose particle shape is recovered after its passing through a catheter or the like. The present invention provides a biodegradable particle comprising a block copolymer produced by copolymerization of: a biodegradable copolymer having a structure composed of hydroxycarboxylic acid a1, whose homopolymer produced by homopolymerization has a glass transition point of not less than 40°C, and hydroxycarboxylic acid a2, whose homopolymer produced by homopolymerization has a glass transition point of not more than -40°C; a water-soluble polymer comprising a functional group selected from the group consisting of a hydroxyl group, amino group and carboxylic acid group at each of both ends; and a polyvalent compound comprising 2 or more functional groups each selected from the group consisting of a hydroxyl group, amino group and carboxylic acid group; wherein the ratio of the mass of the structure composed of hydroxycarboxylic acid a2 to the mass of the biodegradable copolymer is 30 to 90% by mass.