Surface Disinfection Enabled by a Layer-by-Layer Thin Film of Polyelectrolyte-Stabilized Reduced Graphene Oxide upon Solar Near-Infrared Irradiation

We report an antibacterial surface that kills airborne bacteria on contact upon minutes of solar near-infrared (NIR) irradiation. This antibacterial surface employs reduced graphene oxide (rGO), a well-known near-infrared photothermal conversion agent, as the photosensitizer and is prepared by assembling oppositely charged polyelectrolyte-stabilized rGO sheets (PEL-rGO) on a quartz substrate with the layer-by-layer (LBL) technique. Upon solar irradiation, the resulting PEL-rGO LBL multilayer efficiently generates rapid localized heating and, within minutes, kills >90% airborne bacteria, including antibiotic-tolerant persisters, on contact, likely by permeabilizing their cellular membranes. The observed activity is retained even when the PEL-rGO LBL multilayer is placed underneath a piece of 3 mm thick pork tissue, indicating that solar light in the near-infrared region plays dominant roles in the observed activity. This work may pave the way toward NIR-light-activated antibacterial surfaces, and our PEL-rGO LBL multilayer may be a novel surface coating material for conveniently disinfecting biomedical implants and common objects touched by people in daily life in the looming postantibiotic era with only minutes of solar exposure.