Figure 7.

STORM acquisitions of A549 cells treated with TiO₂ NMs. (A) Uncoated TiO₂ at 0 and 18 h, (B) TiO₂-PVP at 0 and 18 h and (C) TiO₂-dispex at 0 and 18 h. At 0 h, uncoated (TiO₂-un), PVP-coated (TiO₂-PVP), and Dispex-AA4040 (TiO₂-AA4040)-coated NMs demonstrate different behaviors. TiO₂-PVP NMs are internalized as discrete, spherical spots which strongly associate with FITC-labeled protein (initial corona). In comparison, uncoated and dispex-AA4040-coated NMs form large agglomerates which associate with both FITC protein and Alexa-647 protein, forming an initial (green) and exchanged (magenta) corona. At 18 h post incubation, TiO₂-PVP NMs have adsorbed a secondary layer of protein and formed larger agglomerates. Conversely, TiO₂-un NMs appear to have lost the FITC-serum signal, and are instead associated with Alexa-647-labeled proteins. Interestingly TiO₂-AA4040 NMs are internalized as large agglomerates which retain their initial corona (FITC) signal at the later time point observed. Reconstructions were performed using the NIS Element STORM module, with a density filter restricting molecules to clusters of 15 molecules within 200 nm.