Figure 6.

Dependence of cytotoxicity on P3HT NPs dose and optical excitation. P3HT NPs at different concentrations, corresponding to OD in the range 0–0.5 (from top to bottom panels), have been administered to HEK-293 cells at the plating step. A sub-set of samples has been treated with the same illumination protocol used for ROS production (CW LED light illumination, peak emission wavelength λ = 540 nm, closely matching the polymer absorption spectrum; photoexcitation density P = 95 mW/mm²; overall duration of the photoexcitation protocol, 2 min), 24 h after NPs administration and upon careful rinsing of the cell growth medium (B, D, F, H, J). All other samples have been subjected exactly to the same preparation protocol, but they did not undergo photoexcitation (A, C, E, G, I). Viable cells are finally detected by FDA staining. Representative images have been acquired at 2 DIV. Scale bar, 100 μm.