Zwitterionic Monomer Surface Layer for Oxygen Permeable Contact Lenses
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Solution Overview
Problem
Current biocompatible materials for ocular devices, such as contact lenses, face challenges in balancing oxygen permeability, water content, and biocompatibility, with limitations in solubility and reactivity of existing zwitterionic monomers like MPC, leading to suboptimal performance and potential biological responses.
Innovation Solution
Development of ethylenically unsaturated monomers with both terminal vinyl groups and zwitterionic groups, which enhance biocompatibility and solubility, allowing for improved copolymerization with vinyl comonomers like N-vinyl pyrrolidone, and the formation of polymers with high oxygen permeability and water content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicone materials are used to improve oxygen permeability, then gas permeability is improved, but the hydrophobic nature causes surface fouling and tear film breakdown
Solution Approach 1:
The patent applies local quality by creating a surface layer with different properties than the bulk material. The contact lens has a hydrophilic surface layer containing zwitterionic groups that provides anti-fouling properties, while the bulk remains silicone-based for high oxygen permeability. This resolves the contradiction by making the surface locally hydrophilic to prevent fouling while maintaining the overall hydrophobic silicone structure for gas permeability.
Solution Approach 2:
The patent uses composite materials by combining silicone polymer base material with hydrophilic zwitterionic surface layers. The composite structure integrates the oxygen permeability benefits of silicone with the anti-fouling properties of hydrophilic surfaces, resolving the contradiction between gas permeability and surface fouling resistance.
2Object-affected harmful factors
If hydrogel systems are used to improve comfort and reduce fouling, then water content and comfort are improved, but oxygen permeability decreases
Solution Approach 1:
The patent applies local quality by concentrating the hydrophilic zwitterionic groups in a surface layer rather than throughout the entire lens. This provides fouling resistance at the surface where it is most needed, while maintaining high oxygen permeability in the bulk silicone material that would be compromised if hydrophilic groups were distributed throughout.
3Object-affected harmful factors
If zwitterionic monomers like MPC are used to improve biocompatibility, then protein adsorption is reduced, but solubility and reactivity are limited
Solution Approach 1:
The patent applies parameter changes by modifying the molecular structure of zwitterionic monomers to improve their solubility and reactivity parameters. The patent uses various zwitterionic monomers with different molecular weights and structural configurations that exhibit improved solubility in polymerization systems while maintaining their biocompatibility and protein adsorption resistance properties.
4Use of energy by moving object
If silicone materials are used to achieve high oxygen permeability, then gas permeability is improved, but the materials become uncomfortable due to low water content
Solution Approach 1:
The patent applies local quality by creating a hydrophilic surface layer that provides water content and comfort at the eye-contact interface, while the bulk silicone material maintains high oxygen permeability. The surface layer is specifically designed to interact with tear films and provide comfort, while the bulk provides gas permeability.
Solution Approach 2:
The patent uses composite materials by combining silicone base material with hydrophilic surface layers containing zwitterionic groups. This composite structure integrates the oxygen permeability benefits of silicone with the comfort and hydration benefits of hydrophilic materials at the surface.
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 new monomers provide biocompatible polymers that offer enhanced oxygen permeability and water content, reducing protein deposition and biological responses, while overcoming solubility and reactivity issues of previous materials.
Implementation Method 1
The adsorption of tear components onto contact lenses results in deposit formation which is problematic
Implementation Method 2
hydrogel systems have a much higher water content than the original rigid gas permeable silicone lenses
Implementation Method 3
ethylenically unsaturated monomers with both terminal vinyl groups and zwitterionic groups, which enhance biocompatibility and solubility, allowing for improved copolymerization with vinyl comonomers
Implementation Method 4
the oxygen permeability of these lenses may be regarded as adequate for daily use but less suitable for extended wear
Implementation Method 5
High gas, in particular oxygen, permeability
Data Source
AI summary
Monomers of formula (I) which include a vinyl group, polymers and articles, such as contact lenses, made therefrom, all of which are biocompatible, are described.