Effect of silver nanoparticles on donkey sperm parameters and ultrastructure

The aim of this study was to determine the effect of silver nanoparticles (AgNPs) on donkey sperm parameters and ultrastructure. AgNPs were synthesized, purified and resuspended in the extender. Nine frozen-thawed donkey sperm samples were exposed to different concentrations of AgNPs (0, 1.25, 2.5, 5, 12.5, 25 and 50 μg/mL). Sperm parameters: total (TMOT, %) and progressive (PMOT, %) sperm motility, plasma (LIVE, %) and acrosomal membrane integrity (AIS, %), and sperm morphology (MORF, %) were evaluated immediately after AgNPs exposure (T0) and after 2 h of incubation (T2). The interaction beween AgNPs and spermatozoa was visualized by transmission electron microscopy (TEM). At T0, sperm motility and AIS were reduced (p < .05) when using concentrations ≥50 and ≥25 μg/mL, respectively. At T2, sperm motility and LIVE were significantly decreased (p < .05) in concentrations ≥25 and ≥50 μg/mL, respectively. TEM analysis revealed nanoparticle adhesion to the acrosomal region of the plasma membrane. In conclusion, AgNPs at concentrations ≥25 μg/mL impair motility, acrosome and plasma membrane integrity of donkey sperm, which may be mediated by adhesion to the acrosomal region of the sperm surface membrane.