Integrating zeta potential with conventional sperm preparation: Comparative effects of swim-up–zeta and density gradient-zeta methods on motility and DNA integrity

Objective: Sperm preparation techniques, such as the swim-up method and density gradient centrifugation, are essential for selecting the highest-quality spermatozoa in the context of assisted reproductive technologies. The zeta method, in which sperm are selected based on their surface electrical charge, has recently emerged as a simple and cost-effective adjunct to improve sperm selection. This study aimed to compare sperm motility and DNA integrity between sperm prepared using a combination of the swim-up and zeta methods (S-Z) and sperm prepared with a combination of density gradient centrifugation and the zeta method (D-Z). Methods: Thirty-nine normozoospermic semen samples were randomly divided into two aliquots. One aliquot was prepared using S-Z and the other using D-Z. Post-preparation sperm motility was assessed using computer-assisted sperm analysis, and DNA integrity was evaluated with acridine orange staining. Results: Both preparation methods significantly reduced sperm concentration compared to neat semen (p<0.001). The total motility rate was significantly higher in the S-Z group (90%) than in the D-Z group (86%) (p<0.001). Normal sperm DNA integrity was comparable between the S-Z (95.0%) and D-Z (95.3%) groups (p=0.582). Conclusion: Integrating the zeta method into conventional sperm preparation techniques may increase the efficiency of sperm selection. The S-Z approach appears particularly effective for recovering highly motile sperm with normal DNA integrity.