Near-infrared and eye tear triggered biocidal corneal bandage for bacterial keratitis therapy

Abstract

Purpose : Antibiotics as the conventional treatment option for bacterial keratitis has raised the problems such as antimicrobial resistance and allergy, and these problems promoted innovation of alternatives for antibiotics. We designed an antibiotics-free biocidal corneal bandage with photo-sensitive nanocomposites embedded in enzyme-modified hydrogel. Nanocomposites and enzyme produce reactive oxygen species (ROS) to disinfect bacteria. The nanocomposites release ROS under near-infrared light (NIR) irradiation, and the enzyme in hydrogel produces ROS by catalyzing glucose in eye tear. Methods : The generation of ROS was characterized using colorimetric analysis, and dyes that can react with ROS were used as the indicators. The antibacterial property of the bandage against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. Aeruginosa) suspended in medium was compared with the blank control group through spread plate method (N=3), Live/dead staining (N=3). The morphology of bacteria was examined by scanning electron microscopy (SEM). The ROS level in bacteria after treated by the bandage under NIR irradiation was also evaluated with DCFH-DA. Results : Dyes were oxidized after treated with bandage under NIR irradiation, and the enzymes on the bandage could also oxidize dye in darkness in the presence of glucose. The living colonies decreased significantly to (52+/-2)% (S. aureus) and (27+/-2)% (P. aeruginosa) after treated by the bandage and NIR irradiation. The antibacterial rates from Live/dead staining were ((54+/-1)% to S. aureus and (83+/-2)% to P. aeruginosa). Severe damage on bacteria membrane and ROS signals were found only in bacteria that were treated by the bandage and NIR irradiation. Conclusions : The catalysis of the dyes indicated that the biocidal corneal bandage produces adequate ROS in the presence of glucose with NIR irradiation. The decreasing of living colonies after treated by the bandage, indicated that our bandage has excellent antibacterial property. The in-vitro results suggested that our bandage has the potential to be a treatment alternative for bacterial keratitis, but further evaluations on ex-vivo and in-vivo models are required to justify its translational potential.