Labile Anionic Polyelectrolyte Binding Cationic Biocides
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Solution Overview
Problem
Cationic biocides used in medical devices and emulsions can cause deleterious effects, such as uptake into contact lenses and instability in emulsions, due to their ionic charge, leading to potential toxicity and discomfort.
Innovation Solution
Incorporating a labile anionic polyelectrolyte, such as cis-diol polymers like galactomannan or polyvinyl alcohol, into compositions with cationic biocides and borate to inhibit uptake into hydrogel biomaterials and stabilize emulsions, maintaining antimicrobial activity while reducing toxicity and improving droplet stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a higher concentration of cationic biocide is used to achieve sufficient antimicrobial activity, then the biocidal effectiveness is improved, but the potential for toxic effects and discomfort increases
Solution Approach 1:
An anionic polymer is introduced as an intermediary substance that selectively binds to cationic biocides through electrostatic interactions. This mediator captures the biocide in the bulk solution, preventing its direct contact with and absorption by contact lenses and ocular tissues, thereby reducing toxicity while preserving antimicrobial activity
Solution Approach 2:
The patent changes the chemical environment by adjusting pH and ionic strength to control the electrostatic interactions between the anionic polymer and cationic biocide. By optimizing these parameters, the system achieves selective binding of biocide to the polymer while maintaining biocidal effectiveness against microorganisms
2Reliability
If cationic biocides are used in emulsion formulations, then antimicrobial protection is provided, but droplet stability deteriorates due to aggregation of negatively charged droplets
Solution Approach 1:
The anionic polymer acts as a mediator that sequesters cationic biocides in the continuous phase through electrostatic binding. This prevents the biocides from interacting with and neutralizing the negative charges on emulsion droplets, thereby maintaining droplet stability while preserving antimicrobial protection
Solution Approach 2:
The anionic polymer extracts or sequesters the cationic biocide from the interface between the continuous phase and emulsion droplets. By removing the biocide from the droplet surface environment, the polymer prevents aggregation while maintaining bulk antimicrobial activity
3Reliability
If cationic biocides are present in lens care solutions, then disinfection capability is achieved, but biocide uptake into contact lenses occurs leading to ongoing irritation
Solution Approach 1:
The anionic polymer serves as an intermediary that binds cationic biocides in the lens care solution. This creates a reservoir of bound biocide that does not penetrate the contact lens, preventing the lens from becoming a source of ongoing irritation while maintaining disinfection capability in the solution
Solution Approach 2:
The anionic polymer applies preliminary anti-action by pre-binding the cationic biocide before it can be absorbed by the contact lens. This preemptive binding prevents the harmful uptake and subsequent release of biocide by the lens, eliminating ongoing irritation
Data Source
AI summary
Methods of inhibiting the uptake of cationic biocides into medical devices such as contact lenses and implants are described. Methods of stabilizing emulsions containing cationic biocides are also described. In particular, the present invention provides for the use of polymers acting as labile anionic polyelectrolytes to reversibly bind cationic biocides. The reversible binding can reduce the deleterious effects of cationic biocides while maintaining biocidal activity. Preferred polymers include galactomannan and polyvinyl alcohol.