Gold nanoparticles improve motility, functional integrity, and antioxidant status of boar spermatozoa during liquid storage.

Liquid preservation of boar semen is widely used in artificial insemination programs; however, storage-induced oxidative stress progressively impairs sperm function and reduces fertility potential. The present study evaluated the effects of gold nanoparticles (AuNPs) on sperm quality, functional integrity, and oxidative status of liquid-preserved boar semen during storage at 17 °C. 24 ejaculates collected from four healthy Lumsniang breeding boars were diluted in Beltsville Thawing Solution (BTS) extender and allocated to three treatment groups: T0 (control, no AuNPs), T1 (5 million AuNPs/ml), and T2 (10 million AuNPs/ml). Extended semen samples were stored for 5 days and evaluated on days 0, 3, and 5. Sperm motility and kinematic parameters were assessed using computer-assisted semen analysis (CASA), while viability, plasma membrane integrity, acrosomal integrity, and mitochondrial membrane potential were determined using CFDA/PI staining, hypo-osmotic swelling test, FITC-PNA staining, and JC-1 staining, respectively. Oxidative status was assessed by measuring malondialdehyde (MDA) concentration and total antioxidant capacity (TAC). Storage duration significantly affected all sperm quality parameters (P < 0.05), resulting in progressive declines in motility, viability, membrane and acrosomal integrity, mitochondrial activity, and antioxidant capacity, accompanied by increased lipid peroxidation. However, AuNP supplementation significantly improved semen preservation compared with the control group. On day 5, semen supplemented with 10 million AuNPs/ml (T2) exhibited higher total motility (30.78 ± 1.53%), progressive motility (17.97 ± 0.94%), viability (47.62 ± 1.38%), plasma membrane integrity (17.25 ± 0.44%), acrosomal integrity (54.91 ± 0.96%), and high mitochondrial membrane potential (41.79 ± 0.79%) than the control (P < 0.05). Furthermore, T2 showed lower MDA concentrations and higher TAC values, indicating enhanced antioxidant protection during storage. These findings demonstrate that AuNP supplementation, particularly at 10 million AuNPs/ml, effectively mitigates oxidative stress and preserves sperm functionality during liquid storage, suggesting its potential application for improving the shelf life and quality of boar semen used in artificial insemination programs.