Graphene Films Irradiated With Safe Low-Power Nir-Emitting Diodes Kill Multidrug Resistant Bacteria

Bacterial adhesion to surfaces is the onset of biofilm formation and a hard problem to tackle, aggravated by the rise in drug-resistant bacteria, responsible for more than 500 000 deaths globally/year. This work reports few-layer graphene (FLG) and few-layer graphene oxide (FLGO) as stand-alone light-responsive platforms to develop smart antibacterial surfaces. Films exposure to low-intensity NIR drastically improve their ability to kill planktonic (up to similar to 99%) and adherent (up to similar to 85%) methicillin-resistant S. aureus and S. epidermidis. Upon irradiation, a mild photothermal effect is observed in supernatant, with temperature rising from 37.0 degrees C to 39.0 degrees C-42.0 degrees C, while surface temperature of non-oxidized FLG films increases to 51.3 degrees C versus 56.0 degrees C for oxidized films. Both films prompt total glutathione oxidation when irradiated, despite FLG films induce higher ROS generation than FLGO, suggesting antioxidants depletion occurs preferentially by ROS-dependent pathway (photodynamic effect) for FLG versus ROS-independent pathway for FLGO films. This proof-of-principle study demonstrates that safe, low-intensity NIR irradiation is a valuable and effective tool to boost graphene surfaces' antibacterial performance through a synergistic photothermal and photodynamic effect. These stand-alone NIR-activated graphene-based platforms arise as simple and economical disinfection surfaces/systems, with wide-spread use in medical and non-medical applications. (C) 2021 Elsevier Ltd. All rights reserved.