Silver nanoparticle induced toxicity to human sperm by increasing ROS (reactive oxygen species) production and DNA damage

Silver nanoparticles (AgNPs) have been used in medical products and industrial coatings, due to their antimicrobial properties. Excessive use of AgNPs can have adverse effects on the human body, however, their toxicity characteristics to human sperm and the potential mechanisms are not entirely clear. In this study, we exposed human sperm to different doses of AgNPs (0, 50 pg ml(-1), 100 mu g ml(-1), 200 mu g ml(-1) or 400 mu g ml(-1)) for various times (15 min, 30 min, or 60 min), followed by analyses of the sperm viability, motility and the ratio of abnormal to normal sperm.Then, transmission electron microscopy(TEM) was used to explore the sperm ultrastructural characteristics. Reactive oxygen species production and DNA fragmentation were tested using standard kits and the sperm chromatin dispersion method, respectively. The results showed a dose- and time dependent decline in sperm viability and motility and an increased ratio of abnormal to normal sperm after 30 min and 60 min of exposure to AgNPs at 200 mu g ml(-1) and 400 mu g ml(-1). The most common abnormalities were sperm heads with disrupted chromatin or absent acrosomes, bent tails, and curved mid-pieces. The ultrastructural characteristics of AgNP-treated sperm included disrupted, swollen, granular and vacuolar defects of the chromatin. In addition, ROS(reactive oxygen species)production and DNA fragmentation were markedly increased after 60 min of exposure to AgNPs at 200 mu g ml(-1) and 400 mu g ml(-1). Our results indicated that AgNPs caused detrimental changes in human sperm characteristics, and the excessive use of AgNPs should be carried out with caution.