Figure 1.

Digital phase contrast images of human astrocytoma cells exposed to surfactants or nanotube/surfactant conjugate solutions under ambient atmosphere at room temperature:acontrol, 60 min;bCNT/DNA, 60 min;cSC, 60 min;dCNT/SC, 60 min;eSDBS, 30 min;fCNT/SDBS, 30 min;gSDS, 30 min; andhCNT/SDS, 30 min. The concentrations of surfactants (b–h) and the SWCNTs (b,d,f, andh) were 0.5 mg/mL and 2 μg/mL, respectively.Arrowsindicate proliferating cells. All images were acquired at 200× magnification directly from the wells.Scale bar: 100 μm