Hydrogels containing water soluble conjugates of silver(i) ions with amino acids, metabolites or natural products for non infectious contact lenses

Abstract

The poor handling and hygiene practices of contact lenses are the key reasons for their frequent contamination, and are responsible for developing ocular complications, such as microbial keratitis (MK). Thus there is a strong demand for the development of biomaterials of which contact lenses are made, combined with antimicrobial agents. For this purpose, the known water soluble silver(i) covalent polymers of glycine (GlyH), urea (U) and the salicylic acid (SalH2) of formulae [Ag3(Gly)2NO3]n(AGGLY), [Ag(U)NO3]n(AGU), and dimeric [Ag(salH)]2(AGSAL) were used. Water solutions ofAGGLY,AGUandAGSALwere dispersed in polymeric hydrogels using hydroxyethyl-methacrylate (HEMA) to form the biomaterialspHEMA@AGGLY-2,pHEMA@AGU-2, andpHEMA@AGSAL-2. The biomaterials were characterized by X-ray fluorescence (XRF) spectroscopy, thermogravimetric differential thermal analysis (TG-DTA), differential scanning calorimetry (DTG/DSC), attenuated total reflection spectroscopy (FT-IR-ATR) and single crystal diffraction analysis. The antibacterial activity ofAGGLY,AGU,AGSAL,pHEMA@AGGLY-2,pHEMA@AGU-2andpHEMA@AGSAL-2was evaluated against the Gram negative speciesPseudomonas aeruginosa(P. aeruginosa) and Gram positive onesStaphylococcus epidermidis(S. epidermidis) andStaphylococcus aureus(S. aureus), which mainly colonize in contact lenses. Thein vitrotoxicity of the biomaterials and their ingredients was evaluated against normal human corneal epithelial cells (HCECs) whereas thein vitrogenotoxicity was evaluated by the micronucleus (MN) assay in HCECs. TheArtemia salinaandAllium cepamodels were applied for the evaluation ofin vivotoxicity and genotoxicity of the materials. Following our studies, the new biomaterialspHEMA@AGGLY-2,pHEMA@AGU-2, andpHEMA@AGSAL-2are suggested as efficient candidates for the development of antimicrobial contact lenses.