Metalloantibiotic functionalized pHEMA for therapeutic contact lenses

Ocular infections remain a major cause of visual impairment worldwide, while the low bioavailability of conventional eye drops limits therapeutic efficacy and patient compliance. Herein, we report the development of therapeutic contact lenses based on poly(2-hydroxyethyl methacrylate) (pHEMA) functionalized with the antibacterial silver(i) metalloantibiotics {[Ag(CipH)₂]NO₃·0.75MeOH·1.2H₂O} (CipAg) and [Ag(pen)(CH₃OH)]₂ (PenAg), yielding the biomaterials pHEMA@CipAg and pHEMA@PenAg, respectively. Successful incorporation of the antimicrobial agents into the hydrogel matrix was confirmed by refractive index, X-ray fluorescence (XRF), solid-state UV-vis spectroscopy and differential scanning calorimetry (DTG/DSC). Among the tested materials, pHEMA@CipAg exhibited the highest antibacterial activity, reducing bacterial viability to 1.3%, 0.4% and 1.4% against P. aeruginosa, S. epidermidis and S. aureus, respectively. Moreover, pHEMA@CipAg generated large inhibition zones ranging from 30 to 41 mm and removed 66.7% and 77.6% of preformed P. aeruginosa and S. aureus biofilms, respectively. The metalloantibiotic-based lenses consistently outperformed the corresponding lenses containing the parent antibiotics, demonstrating the beneficial effect of silver(i) coordination on antimicrobial efficacy. Importantly, the materials displayed acceptable biocompatibility toward human corneal epithelial cells (HCEC), while micronucleus, Artemia salina and Allium cepa assays revealed no significant toxicological concerns.