The macrophage MARCO receptor is uniquely employed to bind and take up the TiO
nanospheres (NS), but has no recognition for the short (NB-1) or long (NB-2) TiO
nanobelts. A, Bright-field microscopy showing uptake of NS in C57BL/6 wildtype AM. Binding and uptake of the NS was significantly hindered in the AM from MARCO null mice. In contrast, B and C panels illustrate no binding or uptake problems in MARCO-deficient AM exposed to either short (NB-1) or long (NB-2) TiO2 nanobelts. MSS values indicate 'median side scatter' which was used as a metric for particle binding. Panel D illustrates the point further, as it shows that the loss of viability and increased apoptosis associated with NB-2 exposure is not affected by MARCO expression on AM. Data expressed as mean ± SEM. Asterisk (*) indicates P < 0.05 compared to control.