Poly-ε-Lysine or Mel4 Antimicrobial Surface Modification on a Novel Peptide Hydrogel Bandage Contact Lens

Microbial keratitis (MK) is a serious issue in many countries and is often caused by contact lens wear. Antimicrobial peptides (AMPs) are a potentially useful tool for creating antimicrobial surfaces in light of increasing antibiotic resistance. Poly--lysine (pK) is an AMP that has been used extensively as a food preservative and Mel4 has recently been synthesised and studied as an antimicrobial coating for contact lenses. A hydrogel synthesised of pK cross-linked with biscarboxylic acids provides a potential lens material which has many surface free amines, that can be subsequently used to attached additional AMPs, creating an antimicrobial lens. The aim of this study was to investigate pεK hydrogels against a clinical strain of Pseudomonas aeruginosa for preventing or treating MK. Covalent attachment of AMPs was investigated and confirmed by fluorescently tagged peptides. Bound pK effectively reduced the number of adherent P. aeruginosa in vitro (>3 log). In ex vivo studies positive antimicrobial activity was observed on bare pK hydrogels and those with additionally bound pK or Mel4; lenses allowed the maintenance of the corneal epithelium. A pεK hydrogel contact lens with additional AMPs could be a therapeutic tool to reduce the incidence of MK