Anionic Silicone Hydrogel Contact Lenses with Controlled Charge Density
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Solution Overview
Problem
Silicone hydrogel contact lenses with added anionic components face issues of hydrolytic instability, increased moduli when exposed to water and heat, and undesirable uptake of positively charged components like PQ1 from multipurpose solutions, while also having higher than desired contact angles and lower oxygen permeability.
Innovation Solution
Development of anionic silicone hydrogel contact lenses with statistical copolymers comprising at least 10 weight % of non-ionic hydrophilic monomers and anionic monomers, which have a contact angle of 70° or less, achieving lysozyme uptake of at least 50 μg/lens and less than 10% uptake of polycationic components from ophthalmic solutions, using a reactive mixture with specific polymerizable components and crosslinkers to control charge density and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If anionic components are added to silicone hydrogels to increase lysozyme uptake, then lysozyme uptake increases, but uptake of polycationic components (PQ1) also increases undesirably
Solution Approach 1:
The patent applies local quality by creating statistical copolymers with non-uniform distribution of anionic groups throughout the silicone hydrogel matrix. This localized arrangement allows selective interaction with lysozyme while minimizing uptake of polycationic components like PQ1, resolving the contradiction between desired protein uptake and unwanted solution component absorption.
Solution Approach 2:
The patent changes the chemical parameter of charge density distribution within the silicone hydrogel by incorporating statistical copolymers with controlled anionic monomer content (at least 10 weight%). This parameter modification enables the material to achieve at least 50 μg/lens lysozyme uptake while maintaining less than 10% PQ1 uptake, simultaneously addressing both requirements.
2Quantity of substance
If anionic components are added to silicone hydrogels, then lysozyme uptake increases, but hydrolytic stability decreases and moduli increase when exposed to water and heat
Solution Approach 1:
The patent employs composite materials by integrating statistical copolymers containing anionic monomers into the silicone hydrogel matrix. This composite structure achieves the desired lysozyme uptake (at least 50 μg/lens) while maintaining hydrolytic stability and appropriate moduli values, even when exposed to water and heat, by balancing the ionic and non-ionic components.
3Quantity of substance
If anionic components are added to silicone hydrogels, then lysozyme uptake increases, but contact angles increase beyond desired levels
Solution Approach 1:
The patent modifies the surface parameter (contact angle) by carefully controlling the composition of statistical copolymers with at least 10 weight% non-ionic hydrophilic monomers. This parameter adjustment enables the contact lens to achieve at least 50 μg/lens lysozyme uptake while maintaining contact angles of 70° or less, satisfying both protein uptake and wettability requirements.
4Quantity of substance
If anionic components are added to silicone hydrogels, then lysozyme uptake increases, but oxygen permeability decreases
Solution Approach 1:
The patent applies local quality by incorporating statistical copolymers with anionic groups in specific locations within the silicone hydrogel matrix. This localized approach allows the material to achieve at least 50 μg/lens lysozyme uptake while preserving oxygen permeability greater than 60, as the anionic components are distributed to minimize impact on gas transport pathways.
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 solution provides stable, low-polar contact lenses with enhanced lysozyme uptake and reduced polycationic component uptake, maintaining oxygen permeability and hydrolytic stability, while maintaining a desirable contact angle and preventing excessive PQ1 uptake.
Implementation Method 1
anionic silicone hydrogel contact lens... at least about 50 μg/lens lysozyme uptake
Implementation Method 2
contact angle of about 70° or less
Implementation Method 3
oxygen permeabilities greater than about 60
Data Source
AI summary
The present invention relates to ionic silicone hydrogel polymers comprising at least one pharmaceutical or nutriceutical component and displaying improved lysozyme uptake, low contact angle and reduced water soluble polymeric ammonium salt uptake.