Spiral Coated Stent Gradient Degradation
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Solution Overview
Problem
Current degradable stents face challenges with uncontrollable degradation fragments, leading to aseptic inflammation and limited clinical application due to the acidic environment caused by degradation products, particularly with polylactic acid and magnesium-based materials, which lack controllable gradient degradation properties.
Innovation Solution
A spiral coated stent with controllable gradient degradation is developed, combining degradable medical polyurethane with a specific chemical structure (PCL-PEG-PCL) and a degradable magnesium alloy, where the polyurethane contains L-lysine diisocyanate as a hard segment and PEG as a soft segment, and the magnesium alloy undergoes surface treatment to achieve gradient degradation, ensuring mechanical integrity and biocompatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If polylactic acid or magnesium-based materials are used as degradable stent materials, then the stent can be degraded in the body, but uncontrollable degradation fragments are produced causing aseptic inflammation and acidic environment
Solution Approach 1:
The patent applies local quality by creating a gradient structure where the stent has different degradation rates in different regions. The surface treatment creates zones with varying degradation speeds, allowing the stent to degrade gradually from the surface inward, preventing sudden release of degradation products that cause inflammation.
Solution Approach 2:
The patent changes the degradation parameter by applying surface treatments (such as oxidation or coating) that modify the degradation rate. This creates a controlled gradient where the degradation time can be adjusted from hours to days, preventing the formation of harmful acidic environments while maintaining structural integrity.
2Ease of manufacture
If magnesium-based materials are used for stent fabrication, then good processability and biocompatibility are achieved, but low corrosion resistance leads to loss of mechanical integrity before tissue healing
Solution Approach 1:
The patent uses composite materials by combining magnesium-based alloy with surface treatment layers or coatings. This composite structure maintains the excellent processability and biocompatibility of magnesium while adding corrosion resistance through the surface layer, preventing premature loss of mechanical integrity.
Solution Approach 2:
The patent applies preliminary surface treatment to the magnesium stent before implantation. This pre-treatment creates a protective layer that slows down corrosion, ensuring the stent maintains its mechanical strength throughout the critical tissue healing period.
3Reliability
If degradable materials are used for stent construction, then the stent can be resorbed by the body, but degradation fragments cause aseptic inflammation limiting clinical application
Solution Approach 1:
The patent changes the degradation time parameter by applying surface treatments that control the degradation rate. This extends the degradation time from hours to days, allowing the stent to maintain structural integrity while degrading gradually, preventing the formation of inflammatory degradation fragments.
Solution Approach 2:
The patent converts the potentially harmful rapid degradation into a beneficial slow, controlled degradation process. By applying surface treatments, the degradation that would normally cause inflammation is transformed into a controlled resorption process that maintains stent function throughout the healing period.
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 stent exhibits improved mechanical properties, reduced risk of inflammation, and controlled degradation, allowing for safer and more effective clinical use by minimizing the risk of secondary operations and enhancing patient comfort.
Implementation Method 1
In a physiological environment of pH (7.4 to 7.6), the magnesium has a strong reduction effect, which leads to the loss of mechanical integrity before a tissue fully heals, and produces hydrogen that cannot be absorbed by the body in time
Implementation Method 2
a soft segment of the degradable medical polyurethane contains a following chemical structure: PCL-PEG-PCL
Data Source
AI summary
Disclosed are a spiral coated stent with controllable gradient degradation, a preparation method thereof and an application thereof. The spiral coated stent with controllable gradient degradation is composed of a degradable medical polyurethane and a degradable magnesium alloy material, wherein the degradable medical polyurethane contains a following chemical structure: PCL-PEG-PCL, wherein a molecular weight of the PEG is 200 to 1,000 and the molecular weight of the PCL is 200 to 10,000, and the degradable magnesium alloy material is of a spiral stent structure; and physical properties of the spiral coated stent with controllable gradient degradation need to satisfy the following technical parameters that: a breaking strength needs to be no less than 1 N, a pressure resistance needs to be no less than 2 N, and a degradation characteristic of the magnesium alloy after surface treatment shows gradient degradation with different time.