In vitro cell/particle interaction captured by SEM (to image the outside of cell), and TEM (to image the inside of the cell) following a 1 hour particle exposure. A, SEM and (E) TEM of unexposed control C57BL/6 alveolar macrophage (AM). B, The SEM and (F) TEM of TiO2 NS-exposed AM revealed a high concentration of particle collection in the cytoplasm of the AM, compartmentalized in lysosomal structures (inset). The SEM revealed no external NS concentration. C, The SEM and (G) TEM of NB-1-exposed AM revealed a similar high concentration of particle collection in the cytoplasm of the AM again compartmentalized in lysosomal structures (inset). The SEM revealed very few NB-1 on the cell surface. D, The SEM of the TiO2 long nanobelt-exposed AM (NB-2) showed many belts on the outside of the cell, as the (H) TEM image illustrated that these belts are also internalized to some degree. The TEM images also suggest there are fewer lysosomal structures associated with the NB-2 exposure in addition to an increased number of belts segments directly exposed to the cell's cytoplasm (inset).