Transmission electron microscope observation of gold labelled MIL5scFv-Arg9 in NIH3T3 cells. Cells incubated with PBS (panel A), 5 nm colloidal gold labelled with MIL5scFv-Arg9 at 1:40 dilution at 37°C for 1 h, 2 h or 5 h (panel B~D); 5 nm colloidal gold labelled with MIL5scFv at 1:40 dilution at 37 °C also for 1 h, 2 h or 5 h (panel E~G), respectively. In one hour, gold particles were found outside or on the membrane of MIL5scFv treated cells (E), while particles can be seen in the endochylema of MIL5scFv-Arg9 treated sample (B). After two hours, gold particles could be found inside cells both in MIL5scFv-Arg9 and MIL5scFv treated samples (C and E), though in figure F they seemed to be near mitochondria. After five hours, the subcellular localization of gold particles in two samples were obviously different, in which MIL5scFv could be seem still in the cytoplasm (D), but MIL5scFv-Arg9 aggregated mainly inside of the mitochondria (G).