Figure 9.

Agglomeration state of particulates before and after exposure. Dispersion of reference and experimental materials in serum-free medium prior to macrophage exposure was evaluated at 5 μg/ml for particles, at 2.5 μg/ml for asbestos fibers, MWCNT 2 and 3, and at 0.5 μg/ml for MWCNT 1. After 14 days of exposure in serum-free medium, 3D cultures were lysed and particulates were recovered and imaged by SEM as described in Materials and Methods. Limited agglomeration of carbon black particles is evident in comparison with larger agglomerates of asbestos and MWCNTs post-exposure.