Fig. 4.

Dichroic targeting using dimer chirality and photodynamic therapy. a, b Live (green, FITC)/dead (red, Texas Red) assays with confocal microscopy for adherent HeLa cells after 30 min illumination under different polarization conditions for NP dimers (with cell penetrating TAT peptides on the NP surface) with 532 nm photons (a) and NR dimers (with cell penetrating TAT peptides on the NR surface) with 660 nm photons (b) with variable and stationary conformations, respectively. c, d Ex vivo singlet oxygen generation as a function of light exposure in model dispersions of NP dimers c or NR dimers d conjugated to PpIX and Ce6 photosensitizers with variable (as in Figs 1c–e) and stationary (labeled as ‘fixed’) conformations (as in Fig. 3), respectively. 5 mW/cm² light at 532 nm for 30 min was used for NP dimers; 5 mW/cm² light at 660 nm for 30 min was used with stationary NR dimers. ~94 molecules of PpIX were conjugated onto each NP and ~116 molecules of Ce6 were conjugated onto each NR. Intracellular conditions for c, d were experimentally reproduced by model cytosol medium as described in the Supplementary Methods; error bars are given for standard deviation of 95%. e, f Viability of cells for different illumination conditions in the presence of various cellular loadings of PpIX (e) and Ce6 (f). The concentrations of photosensitizers were calculated in accordance with the average number of PpIX and Ce6 molecules attached to NP and NR conjugates. Scale bar: 200 μm. The error bars correspond to the standard error of the mean (n = 3)