SEM and TEM images of silica nanoparticles, distribution of particle sizes, and combined labeling. The mean diameter of the PAMAM-coated silica nanoparticles was 20 to 50 nm, as evaluated by scanning electron microscopy (A) and transmission electron microscopy (B). The distribution of the particle sizes was measured using a laser-scattering particle-size analyzer (C). The peak of the distribution was 30 nm in ethanol solution. Combined labeling with both 99mTc and ICG-sulfo-OSu for PCSNs was verified by TLC before each experiment (D). Two-microliter spots of the grafted PCSNs were visualized on TLC plates for NIR fluorescence imaging (above) and contact radiography (below). Verification of the complete graft was confirmed by the lack of flares on either plate.