Flow cytometry evaluations of sperm labeling and viability. Spermatozoa were labeled with 0 nM (Control), 0.1 nM (QD0.1−), and 1 nM (QD1− and QD1+) nanoparticles, followed by their incubation with FITC-PSA to the acrosome integrity or intactness. Proportions of 0%, 76 ± 4%, and 91 ± 2% spermatozoa were labeled with nanoparticles in the Control, QD0.1, QD1−, and QD1+ groups. The mean fluorescence intensities of nanoparticles-labeled spermatozoa (A) and proportions of spermatozoa with intact and damage acrosomes (B) were evaluated. Spermatozoa incubated with 0 and 10 µM calcium ionophore served as negative and positive controls, respectively. Columns (RFI, in A and QD+ intact acrosome, in B) with different letters differ significantly (ANOVA-1; p < 0.05). Data are mean ± SEM of four independent replicates.