In vivo analysis of the biodistribution of fluorescently labelled PEG-SWCNTs. Panels show recording of fluorescence in mice injected with PBS (a) Seta750 (b) and PEG-SWCNT-750 (c). No fluorescence was recorded in control mice (a) at any time. Already 10 min after the injection, animals that received the fluorophore Seta750 alone (b) displayed fluorescence almost exclusively localized in the bladder. High fluorescence was recorded in liver and brown fat of mice administered with PEG-SWCNT-750 (c); one hour after the injection bladder accumulation of fluorescence was also visible in this group.