(a) Schematic illustration of the photothermal ablation of bacteria and their biofilms with gold nanocrosses. Reproduced from ref. 52 with permission from John Wiley and Sons, Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. (b–f) The NIR-mediated photothermal antibacterial effect of chitosan and Fe₃O₄ functionalized graphene oxide on (b) E. coli and (c) S. aureus. (d) The corresponding bacterial colonies treated with chitosan and Fe₃O₄ functionalized graphene oxide, in the presence and absence of NIR. SEM images of (e) E. coli and (f) S. aureus, control experiment and treatment with chitosan and Fe₃O₄ functionalized graphene oxide under NIR radiation. Reproduced from ref. 171 with permission from the Royal Society of Chemistry.