Confocal microscopic images which show the fluorescence intensity of intracellular calcium formation. A–D

<p>: L929 cells treated with 3.5 nm CdTe QDs at 0, 10, 20 and 40 µg/ml (24 h). <b>E–H</b>: L929 cells treated with 2.2 nm CdTe QDs at 0, 10, 20 and 40 µg/ml for 24 h. <b>I</b>: Quantification of fluorescence intensity. Results represent the mean ± SD of three independent experiments. One-way analysis of variance followed by Dunnett’s post hoc test was used for statistical analysis. *p<0.05, indicates statistically significant difference compared with the control.