Antimicrobial efficacy and ocular cell toxicity from silver nanoparticles

Area of Science:

• Ophthalmology
• Nanotechnology
• Microbiology

Background:

• Silver possesses known antimicrobial properties beneficial for biomedical applications.
• Ocular drug delivery faces challenges due to rapid clearance, reducing efficacy and potentially causing systemic side effects.

Purpose of the Study:

• To investigate silver nanoparticles (AgNPs) as a controlled-release source of antimicrobial silver for contact lens formulations.
• To evaluate the antimicrobial efficacy and safety of AgNPs in vitro for ocular applications.

Main Methods:

• Assessed in vitro silver ion release from various AgNP sizes and doses over several weeks.
• Tested antimicrobial activity against Pseudomonas aeruginosa (PA01).
• Evaluated mammalian cell viability and cytokine expression using corneal epithelial cells and macrophages.

Main Results:

• Minimal microcidal and cell toxic effects were observed at tested AgNP concentrations.
• Insufficient silver ion release was detected to cause significant biological effects in vitro.
• Silver particles themselves were not microcidal under the tested conditions.

Conclusions:

• Current AgNP loadings in contact lenses do not provide sufficient antimicrobial silver ion release for efficacy.
• Increased AgNP loading in lenses may be necessary to achieve bactericidal effects against bacterial colonization.
• AgNPs offer a potential strategy for managing bacterial issues in extended-wear contact lenses if loading is optimized.