Fig. 5

Radiosensitizing effects of bare nanocomposites and DOPAC-coated nanoconjugates. a, c SK-N-AS and b, d SK-N-DZ cells were irradiated in the presence of bare (Bare-NCs) or DOPAC-coated (DOPAC-NCs) nanoconstructs of different concentrations. Curves were generated by adjusting cell viabilities to 100% for non-irradiated cells in each nanoconstruct treated group. A statistically significant radiosensitizing effect was observed at 250 nM bare nanocomposites in both cell lines, particularly at 10 Gy. Datapoints presented are average of 5 biological replicates and are representative of at least two independent MTS experiments. Error bars indicate mean ± SD. e Annexin V/propidium iodide flow cytometry assay of SK-N-AS cells 24 h after irradiation (0 or 10 Gy) preceded by treatment with 250 nM DOPAC-nanocomposites. H₂O₂ was the positive control. Three independent experiments were done, with 3 biological replicates per experiment. Con = cells not exposed to nanoconjugates; NC = DOPAC nanoconjugate treatment; f percentage of SK-N-AS cells with > 20 foci per nucleus, for untreated or treated with 250 nM bare nanocomposites or 250 nM DOPAC-nanoconjugates for one hour and irradiated as indicated. 53BP1 foci were stained by immunocytochemistry while the nuclei were counterstained with propidium iodide (PI). At least 100 cells were counted for each treatment group per replicate. N = total number of biological replicates from 4 independent experiments of 1–2 replicates each. There was a significant increase in the percentage of cells with > 20 foci after 2 Gy treatment. g Representative images of cells shown in f. Error bars indicate mean ± SD. * < 0.05 significance level, ** < 0.01 significance level, *** < 0.001 significance level when treatment sample is compared to untreated and/or unirradiated control