Infant Vascular Stent Coating with Chitosan-PPDO Micelles
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Solution Overview
Problem
Current absorbable vascular stents for infants with angiostenosis face challenges such as poor biocompatibility, inflammation, and thrombosis during degradation, which affect their efficacy and longevity, and there is a lack of stents designed specifically for infants with these conditions.
Innovation Solution
A drug-loaded composite coating for absorbable vascular stents using a chitosan-poly(p-dioxohone) amphiphilic block copolymer, which allows for controlled drug release during the stent's degradation phase to prevent inflammation and proliferation, ensuring biodegradability without increasing thrombosis risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If polymer absorbable stents are used for infant angiostenosis, then the stent can be completely degraded and fused with vascular wall, but the stent has poor biocompatibility at middle stage of degradation causing inflammation and thrombosis
Solution Approach 1:
The stent is pre-coated with drugs (such as anti-inflammatory and anti-proliferation drugs) before implantation. During the middle stage of degradation when inflammation and thrombosis risk is highest, these pre-loaded drugs are released to actively prevent harmful reactions, rather than waiting for the body's natural response.
Solution Approach 2:
The degradation process itself, which normally causes inflammation and poor biocompatibility, is converted into a beneficial process by coupling it with controlled drug release. The degradation products trigger drug release that actively prevents the harmful inflammatory response, turning the harmful degradation byproducts into a trigger for protective therapy.
2Duration of action of stationary object
If polymer absorbable stents are used for infant angiostenosis, then the stent can be completely degraded, but the degradation cycle is too long (2-3 years) for infant vascular development
Solution Approach 1:
The patent modifies the polymer composition and coating formulation to achieve faster degradation kinetics. By adjusting the polymer blend ratios (e.g., PLLA-PLGA-PPDO combinations) and coating thickness, the degradation time is reduced from 2-3 years to 6-12 months, matching infant vascular growth rates while maintaining adequate support duration.
3Strength
If traditional metal stents are used for infant angiostenosis, then the stent provides strong radial support, but the stent causes relative narrowing, repeated dilation, and thrombogenicity as the infant grows
Solution Approach 1:
The patent uses polymer material parameter optimization to achieve adequate radial support (though lower than metal) combined with complete biodegradability. The stent provides sufficient support during the critical 6-12 month period while gradually degrading, eliminating long-term thrombogenicity and allowing vascular growth without the constraints of permanent metal structures.
4Shape
If degradable polymer stents are prepared by melt spinning or solution casting, then the stent structure can be formed, but the production cost is high and the method is complicated
Solution Approach 1:
The patent combines the stent structure formation and drug coating into a single integrated process. The drug-coated polymer filaments are directly woven into stent structures during the manufacturing process, eliminating separate coating and assembly steps, thereby reducing production complexity and cost while maintaining structural integrity.
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 coating maintains reendothelialization of damaged vessels, provides anti-inflammatory and anti-proliferation effects, and ensures complete biodegradability, enhancing the stent's biocompatibility and vascular repair support for infants.
Implementation Method 1
chitosan-poly(p-dioxohone) amphiphilic block copolymer
Implementation Method 2
allows for controlled drug release during the stent's degradation phase
Implementation Method 3
degradation products of these materials are safe and non-toxic and can be excreted through cell metabolism
Data Source
AI summary
A preparation method of drug-loaded micelles of an absorbable vascular stent coating for angiostenosis in an infant is provided, including the following steps: S1: dissolving a drug to be encapsulated in an appropriate amount of an emulsifying agent, adding a chitosan-poly(p-dioxohone) amphiphilic block copolymer (chitosan-b-PPDO copolymer), and thoroughly mixing to obtain a drug-copolymer solution; S2: adding the drug-copolymer solution obtained in S1 dropwise to an emulsifying agent aqueous solution prepared in advance, and continuously stirring to obtain a stable drug-loaded micellar solution; and S3: removing the emulsifying agent from the micellar solution obtained in S2 through vacuum evaporation, stirring a resulting concentrate, and centrifuging the concentrate to obtain a supernatant; and filtering the supernatant to obtain a filtrate, and subjecting the filtrate to dialysis to obtain the drug-loaded micelles.