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 of AGGLY, AGU and AGSAL were dispersed in polymeric hydrogels using hydroxyethyl-methacrylate (HEMA) to form the biomaterials pHEMA@AGGLY-2, pHEMA@AGU-2, and pHEMA@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 of AGGLY, AGU, AGSAL, pHEMA@AGGLY-2, pHEMA@AGU-2 and pHEMA@AGSAL-2 was evaluated against the Gram negative species Pseudomonas aeruginosa (P. aeruginosa) and Gram positive ones Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus), which mainly colonize in contact lenses. The in vitro toxicity of the biomaterials and their ingredients was evaluated against normal human corneal epithelial cells (HCECs) whereas the in vitro genotoxicity was evaluated by the micronucleus (MN) assay in HCECs. The Artemia salina and Allium cepa models were applied for the evaluation of in vivo toxicity and genotoxicity of the materials. Following our studies, the new biomaterials pHEMA@AGGLY-2, pHEMA@AGU-2, and pHEMA@AGSAL-2 are suggested as efficient candidates for the development of antimicrobial contact lenses.
Highlights
The use of soft contact lenses is a popular method for correcting eye refractive errors.[1]
The inhibition zones which were developed in agar plates of P. aeruginosa, E. coli, S. epidermidis and S. aureus microbes around the pHEMA@AGGLY-2, pHEMA@AGU-2 and pHEMA@AGSAL-2 discs suggest mild antimicrobial activity (Table 1 and Fig. 8)
Since the contact lens wear can be implicated with the occurrence of microbial keratitis (MK), novel active biomaterials pHEMA@AGGLY-2, pHEMA@AGU-2, and pHEMA@AGSAL-2 were synthesised by the dispersion in pHEMA of the known water soluble silver(I) covalent polymers AGGLY, AGU and AGSAL of the natural products GlyH, U and SalH2
Summary
The use of soft contact lenses is a popular method for correcting eye refractive errors.[1]. The discs of pHEMA, pHEMA@AGGLY-2, pHEMA@AGU-2, pHEMA@AGSAL-2, were placed in tests tubes with the bacterial strains P. aeruginosa, S. epidermidis and S. aureus (Fig. 5).
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