Size-dependent cryoprotective effects of curcumin nanoparticles on DNA integrity and motility in cryopreserved Angora buck sperm

Curcumin is a potent antioxidant and anti-inflammatory agent derived from the Curcuma longa plant. However, its low water solubility and limited bioavailability restrict its effectiveness in cryopreservation applications. In this study, curcumin nanoparticles (CNp) were produced in two different sizes (20 and 80 nm) to increase bioavailability, and their effects on the freezing of Angora buck sperm were investigated. Semen was collected a total of six times from five Angora bucks (aged 2–3 years). The collected semen was pooled in equal volumes, diluted with a Tris-based egg yolk diluent, and distributed among the experimental groups. Experimental groups set as: control, CNp 20–1 (20 nm CNp at 1 μg/ml), CNp 20-5 (20 nm CNp at 5 μg/ml), CNp 80–1 (80 nm CNp at 1 μg/ml), and CNp 80-5 (80 nm CNp at 5 μg/ml), and were drawn into 0.25 ml straws and frozen. After thawing, motility, kinematic parameters, plasma membrane and acrosomal integrity (PMAI), mitochondrial membrane potential (MMP), and DNA integrity analyses were performed. The highest motility value was observed in the CNp 20-1 group (p < 0.05), but the groups containing 80 nm CNp reduced MMP (p < 0.01). There was no statistical difference between groups in PMAI. DNA integrity remained within acceptable limits in all groups and was better preserved compared to the control group (p < 0.05). In addition to these findings, dynamic light scattering (DLS) analyses revealed that CNps exhibited increased water-absorbing capacity and aggregation. The hydrodynamic diameters of 20 and 80 nm CNps were found to be 223.3 and 289.3 nm, respectively. The findings indicate that the size of curcumin nanoparticles significantly affects aggregation behavior, motility, and DNA integrity parameters. These results suggest that curcumin nanoparticles with a 20 nm size may offer a more effective strategy for the cryopreservation of Angora buck sperm.