Antimicrobial activity of a short guanidine mimic immobilised on contact lenses

The advancement of antimicrobial contact lenses presents a promising strategy for mitigating microbial keratitis. This study investigated the antimicrobial activity of four guanidine-substituted anthranilic amide peptidomimetics (GAMPs), identifying RK1083 as the most potent candidate. The minimum inhibitory concentrations ranged from 20 to 86 µM, with therapeutic indices between 2 and 22. All tested GAMPs exhibited resistance to proteolytic degradation. RK1083 was covalently immobilized onto contact lenses using carbodiimide chemistry, oxazoline plasma deposition, and plasma immersion ion implantation (PIII). The modified lenses demonstrated increased nitrogen content (≥3%), changes in surface charge, and improved hydrophilicity. Adhesion of Staphylococcus aureus was reduced by 5 log₁₀, while Pseudomonas aeruginosa adhesion decreased by ≥5 log₁₀ on oxazoline and PIII-treated lenses, and by ≥3 log₁₀ on carbodiimide-treated lenses. RK1083-coated surfaces exhibited no cytotoxicity toward corneal epithelial cells, and carbodiimide-treated lenses maintained antimicrobial activity post-sterilization. These results underscore RK1083's potential for enhancing antimicrobial contact lens surfaces with improved bacterial resistance.