Upon excitation with near-infrared light (980 nm), PEGylated W 18O49 nanowires can sensitize the formation of singlet oxygen and thus reactive oxygen species (ROS). The resulting photodynamic therapy (PDT) effect can cause the destruction of tumors in the absence of organic photosensitizers. PEG=poly(ethylene glycol), PTT=photothermal therapy. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.