Antimicrobial Contact Lens with Silver Nanoparticles

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Solution Overview

Problem

Current contact lenses lack long-term antimicrobial activity, broad-spectrum efficacy, and compatibility with ocular health and comfort, especially for extended wear, due to limitations in existing antimicrobial coatings and materials.

Innovation Solution

A method involving the incorporation of silver nanoparticles into a polymerizable fluid composition for contact lenses, using a siloxane-containing macromer and a soluble silver salt to form a stable polymerizable dispersion, which is then polymerized to create an antimicrobial contact lens with high oxygen and ion permeability, providing sustained antimicrobial activity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If antimicrobial coatings containing covalently bound antimicrobial agents are used, then duration of antimicrobial activity is improved, but oxygen permeability deteriorates

Engineering Contradiction:

Improveduration of antimicrobial activityVSAvoidoxygen permeability

Core Design Contradiction:

Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical-chemical state of silver from bulk metal to nanoparticle form (1-100 nm diameter), which fundamentally alters its properties. The nanoparticulate form provides high surface area to volume ratio for enhanced antimicrobial activity while maintaining small size that allows oxygen permeability, resolving the contradiction between duration of activity and oxygen transmission

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The contact lens comprises a composite material system combining polymeric lens material with dispersed silver nanoparticles. This composite structure integrates the antimicrobial functionality of silver with the optical and permeability properties of the polymeric matrix, achieving both long-term antimicrobial activity and adequate oxygen permeability

Inventive Principle:

Principle #40Composite materials

2Reliability

If antimicrobial compounds are incorporated into polymeric composition, then antimicrobial activity is improved, but surface properties such as hydrophilicity and lubricity deteriorate

Engineering Contradiction:

Improveantimicrobial activityVSAvoidsurface properties

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The silver nanoparticles are distributed throughout the bulk material rather than forming a continuous coating layer on the surface. This localized distribution within the matrix allows the surface to maintain its native hydrophilic and lubricious properties while the bulk provides antimicrobial activity through nanoparticle release or ion diffusion

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The use of nanoparticulate silver changes the delivery mechanism from surface-bound compounds that interfere with surface properties to dispersed particles that can release antimicrobial agents gradually without compromising the polymeric surface characteristics essential for comfort and ocular health

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If leachable antimicrobial agents are used in coatings, then ease of manufacture is improved, but duration of antimicrobial activity deteriorates

Engineering Contradiction:

Improveease of manufactureVSAvoidduration of antimicrobial activity

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent utilizes the natural leachable property of silver nanoparticles but controls the release rate through nanoparticle stabilization and matrix integration. The nanoparticulate form allows gradual release of silver ions over extended periods, transforming a short-lived leachable system into a long-duration antimicrobial source while maintaining manufacturing simplicity

Inventive Principle:

Principle #35Parameter changes

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 resulting antimicrobial contact lens exhibits a significant reduction in viable microorganisms, maintaining effectiveness for extended periods without adverse effects on ocular health or comfort, with high oxygen and ion permeability ensuring corneal health and comfort.

Implementation Method 1

a vinylic monomer capable of reducing silver cations

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 2

forming a polymerizable dispersion comprising silver nanoparticles and having a stability of at least about 60 minutes

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 3

polymerizing the polymerizable dispersion in the mold to form the antimicrobial medical device containing silver nanoparticles

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentUS8425926B2Antimicrobial medical devices

Publication Date: 2013.04.23 ALCON INC

AI summary

The present invention provides methods for making an antimicrobial medical device, preferably an antimicrobial ophthalmic device, more preferably an antimicrobial extended-wear contact lens, which contains silver nano-particles distributed uniformly therein. The antimicrobial medical device can exhibit antimicrobial activity over an extended period of time.