Chitosan-Coated Urinary Catheters With Plasma Surface Activation
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Solution Overview
Problem
Chitosan coatings on urinary catheters face issues with adhesion to hydrophobic polymer blends and slow water absorption, limiting their effectiveness as a lubricating and antibacterial coating.
Innovation Solution
A four-step method involving low-pressure non-equilibrium gaseous plasma treatment to make the catheter surface hydrophilic, followed by chitosan application and additional plasma treatment to enhance wettability, resulting in a uniform and rapidly swelling chitosan film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chitosan is applied as a coating on hydrophobic polymer catheters, then antibacterial properties are improved, but adhesion of the coating is worsened
Solution Approach 1:
The patent introduces a coupling agent as an intermediary substance between the hydrophobic polymer catheter and the hydrophilic chitosan coating. This coupling agent contains both hydrophobic groups that bond to the polymer surface and hydrophilic groups that bond to chitosan, thereby mediating the adhesion interface and resolving the adhesion problem while preserving antibacterial properties
Solution Approach 2:
The patent modifies the surface parameters of the catheter by treating it with plasma or chemical agents to change its surface energy and wettability. This parameter change enables the hydrophobic surface to better accept the hydrophilic chitosan coating, improving adhesion without compromising the antibacterial function
2Stability of the object's composition
If dry chitosan is used for coating, then storage stability is improved, but water absorption speed is worsened
Solution Approach 1:
The patent applies a preliminary plasma treatment or surface activation to the catheter before chitosan coating. This preliminary action creates surface groups that accelerate subsequent water absorption when the coated catheter is deployed, while the coating itself remains in a stable dry state during storage
Solution Approach 2:
The patent creates a composite coating structure combining chitosan with hydrophilic polymers or porous materials. This composite structure maintains storage stability of dry chitosan while incorporating components that enable rapid water absorption and swelling upon contact with bodily fluids
3Ease of operation
If the catheter surface is made hydrophilic, then insertion comfort is improved, but coating uniformity is worsened due to rapid water absorption
Solution Approach 1:
The patent performs preliminary surface treatment to create controlled hydrophilic sites that guide uniform coating deposition. This preliminary action ensures that when chitosan is applied, it distributes evenly across the surface before rapid water absorption occurs during use
Solution Approach 2:
The patent creates local variations in surface properties during manufacturing, with different zones having controlled hydrophilicity. This local quality control allows uniform coating application in manufacturing while ensuring rapid water absorption and lubrication at the insertion surface during medical use
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 method ensures excellent lubrication and antibacterial properties with rapid water absorption, making the catheters suitable for medical use.
Implementation Method 1
treatment with gaseous plasma, wherein the outer surface of a catheter is subjected to a flux of reactive species and radiation
Implementation Method 2
the dried chitosan, however, wets slowly upon soaking with water
Implementation Method 3
chitosan-coated catheters with a hydrophilic character
Data Source
Figure 1~2
AI summary
The present invention relates to methods for optimization of the sliding properties of urinary catheters. The urinary catheters are first treated with a non-equilibrium gaseous plasma sustained in reactive gases or a mixture of a reactive gas with a noble gas. The first treatment enables a hydrophilic surface finish when oxygen is a reactive gas and an almost super-hydrophilic finish when the catheter is treated with hydrogen plasma followed by oxygen plasma. The hydrophilicity of the surface finish obtained upon the first plasma treatment is beneficial for adhering a layer of water solution of chitosan, which spreads uniformly on the entire outer surface of the catheter. The catheter with a layer of water solution of chitosan is dried and then treated with plasma containing an oxidative gas for better absorption of water by the dried chitosan film.