Fig. 5

The visual changes in the lung tissue homogenates after incubation with proteinase K (PK). Carbon black (CB) was selected as a representative CNM and a mixture of CB at 25 μg and lung tissue homogenates at 0.02 g (dry weight) were incubated in 1 mL of Tris buffer (pH 8.0) containing 200 μg PK. After 24 h samples were washed by centrifugation and incubated for another 24 h in 1 mL of Tris buffer (pH 8.0) containing 200 μg PK. Note that CB could be completely recovered from the lung tissue homogenates following PK digestion and centrifugation. The perfusion step did not influence nanomaterial recovery