Fig. 2. Cellular imaging of Gd–GFP³⁶⁺–dLBT. (A) Confocal laser microscopy images of HeLa cells treated with PBS (left) or 1 μM Gd–GFP³⁶⁺–dLBT (right) for 4 h. In blue: nuclear staining (DAPI), in green: GFP³⁶⁺. The scale bar is 15 μm. (B) Gd content in HeLa cells measured using ICP-MS after incubation with Gd-DTPA or Gd–GFP³⁶⁺–dLBT for 4 h. Data are shown as the mean ± SD of three independent experiments. (C) T₁-weighted MR images of 2 × 10⁶ HeLa cells treated with Gd-DTPA or Gd–GFP³⁶⁺–dLBT at different concentrations. Cells were washed 5 times to remove the free protein.