Electrospun Nanofiber Coating for Vascular Prostheses
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Solution Overview
Problem
Conventional vascular prostheses and stents face challenges in manipulating mechanical properties, cellular proliferation, fluid permeability, adhesion to structural frames, and incorporating active therapeutic components, while also struggling to coat complex geometries effectively.
Innovation Solution
A process involving the electrospinning of polymeric nanofibers onto a tubular frame or structure, forming a composite prosthetic device with layers of expanded polytetrafluoroethylene (ePTFE) and electrostatically spun PTFE fibers, allowing for varied pore structures and enhanced bonding, cellular response control, and integration of bioactive agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ePTFE mechanical formation methods are used to create microporous structure, then tissue ingrowth and cell endothelialization are enhanced, but mechanical property manipulation and cellular proliferation control are difficult
Solution Approach 1:
The patent applies parameter changes by controlling electrospinning process variables (voltage, flow rate, collection distance) and dispersion composition (polymer concentration, solvent type, additive content) to systematically adjust fiber diameter, pore size, porosity, and mechanical strength. This enables independent optimization of multiple properties that were previously coupled in conventional ePTFE formation.
Solution Approach 2:
The invention uses composite materials by incorporating multiple polymers (e.g., PTFE with PEO or PVA), adding bioactive agents (growth factors, antibiotics, anti-proliferative drugs), and combining different fiber orientations within the electrospun mat. This creates multifunctional structures that simultaneously provide mechanical support, controlled porosity, and therapeutic functionality.
2Ease of manufacture
If conventional ePTFE coating methods are used, then simple geometries can be covered, but complex geometries cannot be effectively coated
Solution Approach 1:
The patent replaces mechanical coating methods (extrusion, dipping, spraying) with electrostatic field-based electrospinning. The charged polymer jets are attracted to and deposited on the substrate by electrostatic forces, allowing the coating to conform to any geometry including complex stent structures, branched vessels, and irregular surfaces that mechanical methods cannot access.
Solution Approach 2:
The invention adds the dimension of electrostatic field control to the coating process. By applying high voltage between the spinneret and substrate, the process transitions from purely mechanical contact-based coating to field-guided deposition, enabling uniform coating on three-dimensional complex geometries from all angles.
3Reliability
If high porosity is achieved to promote tissue ingrowth, then fluid permeability increases, but mechanical strength decreases
Solution Approach 1:
The patent applies local quality by creating spatial variations in fiber density, diameter, and orientation within different regions of the electrospun mat. The inner surface near the lumen can have higher porosity and larger pores to facilitate cell ingrowth and endothelialization, while the outer surface or deeper layers can have higher fiber density and smaller pores to provide mechanical strength and structural support.
Solution Approach 2:
The invention segments the wall structure into multiple functional layers with distinct properties: an inner highly porous layer for tissue integration, a middle transition layer for mechanical reinforcement, and an outer layer for structural integrity. This segmentation allows each layer to be optimized for its specific function without compromising overall device performance.
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
Enables the creation of prosthetic devices with improved mechanical properties, enhanced cellular interaction, and therapeutic capabilities, including the ability to coat complex geometries, thereby expanding therapeutic applications and structural integrity.
Implementation Method 1
Nanofibers from the dispersion are electrospun onto the tubular frame to form a prosthetic device
Implementation Method 2
The prosthetic device is heated
Data Source
AI summary
In accordance with certain embodiments of the present disclosure, a process of forming a prosthetic device is provided. The process includes forming a dispersion of polymeric nanofibers, a fiberizing polymer, and a solvent, the dispersion having a viscosity of at least about 50,000 cPs. A tubular frame is positioned over a tubular polymeric structure. Nanofibers from the dispersion are electrospun onto the tubular frame to form a prosthetic device. The prosthetic device is heated.