Researchers recently investigated the effects of incorporating silver nanoparticles (AgNPs) into silicone hydrogel composite films in hopes of imparting antimicrobial activities. They found that adding AgNPs into the material—one similar to that used for contact lenses—inhibited bacterial growth, reduced biofilm formation and enhanced some mechanical properties of silicone hydrogel film.

The researchers first created the composite material by adding several different concentrations of silver ions (0ppm, 10ppm, 20ppm, 30ppm, 40ppm, 60ppm and 80ppm) to the silicone hydrogel film and then hitting it with ultraviolet (UV) light to cure it. With the new composite film in hand, they then tested it against several bacterial strains common in contact lens wearers: Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Finally, they evaluated the antimicrobial activity and biofilm formation.

The team, based in Cairo, found that as the AgNPs concentration increased, the mechanical properties of the material were enhanced without affecting its chemical and thermal properties. In addition, when the nanoparticle-infused composite films were bathed in solutions with bacterial loads, organism growth slowed as the silver concentration increased. While a material sample lacking silver nanoparticles led to a 93% bacterial growth for Staphylococcus aureus, nanoparticle concentrations of 40, 60 or 80ppm all showed 0% bacterial growth. The study showed similar results for Escherichia coli and Pseudomonas aeruginosa.

Incorporating these silver nanoparticles into the silicone-hydrogel composite films “demonstrated sufficient release of AgNPs to inhibit bacterial growth and reduce biofilm formation,” the study concludes.

Mourad R, Helaly F, Darwesh O, et al. Antimicrobial and physicomechanical natures of silver nanoparticles incorporated into silicone-hydrogel films. Cont Lens Anterior Eye. February 28, 2019. [Epub ahead of print]