Fe/Pt Magnetic Coating for Cell Retention on Stents
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Solution Overview
Problem
Current cardiovascular stents face challenges with restenosis and thrombosis due to neointimal proliferation and limited long-term safety, necessitating improved compositions and methods for enhanced tissue repair and cell retention on device surfaces.
Innovation Solution
Iron/platinum (Fe/Pt) particles are dispersed in a polymer and magnetized to create devices that attract and retain magnetically labeled cells, forming a stable endothelial surface, with annealing at 700°C to achieve a ferromagnetic state and minimize particle disintegration, and are used in stents and other implants to prevent restenosis and thrombosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional stents are used, then basic structural support is provided, but restenosis and thrombosis occur due to neointimal proliferation
Solution Approach 1:
The stent is pre-coated with Fe/Pt particles and polymer matrix before implantation, creating a prepared surface that will subsequently attract and retain magnetically labeled progenitor cells. This preliminary preparation enables the stent to actively recruit therapeutic cells to the implantation site, addressing restenosis and thrombosis through biological repair mechanisms rather than passive structural support alone
Solution Approach 2:
The invention uses a composite coating system consisting of Fe/Pt particles embedded in a polymer matrix on the stent surface. This composite structure provides both mechanical stability and magnetic functionality, allowing the stent to maintain structural integrity while enabling magnetic cell attraction and retention. The composite material approach resolves the contradiction by combining structural support with active therapeutic cell recruitment capabilities
2Strength
If Fe/Pt particles are used without annealing, then particle disintegration occurs, but magnetic field strength is insufficient for effective cell retention
Solution Approach 1:
The Fe/Pt particles undergo annealing treatment at elevated temperatures (typically 400-800°C) to transform their magnetic properties from paramagnetic to ferromagnetic state. This parameter change in magnetic strength enables the particles to generate sufficient magnetic field for effective cell attraction and retention. The annealing process simultaneously stabilizes the particle composition and prevents disintegration by creating a more stable crystalline structure
Solution Approach 2:
The annealing process induces a phase transition in the Fe/Pt particles from a paramagnetic phase to a ferromagnetic phase. This phase transition is critical for achieving the necessary magnetic field strength for cell retention. The phase change occurs through thermal treatment that reorganizes the magnetic domains within the particles, transforming them into a state capable of maintaining persistent magnetic moments for effective cell attraction
3Reliability
If cells are exposed to biological fluid flow, then natural cell distribution occurs, but cell retention on device surface is insufficient
Solution Approach 1:
The invention replaces passive mechanical cell adhesion with active magnetic field-based cell retention. Instead of relying solely on mechanical forces that must overcome biological fluid flow, the magnetic field exerts a force on magnetically labeled cells that is sufficient to counteract the hydrodynamic forces of blood flow. This substitution of magnetic force for mechanical adhesion enables effective cell retention in the high-flow environment of blood vessels
Solution Approach 2:
Cells are pre-labeled with magnetic particles before administration to the patient, preparing them for magnetic attraction to the stent. This preliminary magnetic labeling ensures that when cells encounter the magnetized stent surface in the presence of biological fluid flow, they experience immediate and strong magnetic attraction that overcomes the flow forces, enabling effective retention and accumulation at the implantation site
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 magnetized Fe/Pt devices effectively capture and retain cells for extended periods, enhancing tissue integration and reducing restenosis and thrombosis, while maintaining stability under biological fluid flow, thereby improving vascular repair and reducing complications post-implantation.
Implementation Method 1
Iron/platinum (Fe/Pt) particles are dispersed in a polymer and magnetized to create devices that attract and retain magnetically labeled cells
Implementation Method 2
annealing at 700°C to achieve a ferromagnetic state
Implementation Method 3
annealing at 700°C to achieve a ferromagnetic state and minimize particle disintegration
Data Source
AI summary
It has been discovered that iron-platinum ferromagnetic particles can be dispersed in a polymer and coated into or onto, or directly linked to or embedded on to, medical devices and magnetized. The magnetized devices are used to attract, capture, and/or retain magnetically labeled cells on the surface of the device in vivo. The magnetic particles have an iron/platinum core. Annealing the Fe/Pt particle is very important for introducing a L10 interior crystalline phase. The Fe:Pt molar ratio for creation of the crystal phase is important and a molar range of 1.2-3.0 Fe to Pt (molar precursors, i.e. starting compounds) is desired for magnetization. The magnetic force as a whole can be measured with a “Super Conducting Quantum Interference Device”, which is a sensitive magnetometer. The overall magnetic force is in the range from 0.1 to 2.0 Tesla.