Fig. 6

Evaluation of efficient intracellular release for different radiant exposures. Cells with endosomes containing CPP-AuNPs and calcein irradiated with different radiant exposures. The release efficiency was determined by the amount of cells per image with 3–50 cells showing relevant fluorescent change according to the chosen criteria. Results are similar to the decision by eye (samples without AuNPs and with non-CPP-AuNPs show this ratio). Spikes (maximal ratio: \(\times\)) are due to analysis. Threshold is found at 25 mJ/cm\(^{2}\), efficient release for all higher radiant exposures. A two-tailed t-test revealed a significant increase compared to lower radiant exposures or control samples (***p \(<\) 0.001, *p \(<\) 0.04). Box: first to third quartile, line: median