The dual effects of nanomaterials on sperm and seminal fluid oxidative stress.

Nanomaterials, due to their unique physicochemical properties, have found widespread applications in biomedical, energy, and environmental fields. Currently, their effects on the male reproductive system are also under investigation. Oxidative stress, a pathological condition resulting from an imbalance between the generation and clearance of reactive oxygen species (ROS), is a critical mechanism affecting male reproductive function. Therefore, this review focuses on the regulatory mechanisms of various nanomaterials on semen oxidative stress, synthesizing literature data and evaluating their effects and molecular underpinnings. Previous studies indicate that nanomaterials exhibit dual effects: some materials (e.g. selenium, cerium dioxide nanoparticles) mimic the activity of superoxide dismutase (SOD) and catalase (CAT), or enhance endogenous antioxidant systems such as glutathione peroxidase (GPx), significantly reducing ROS levels and improving sperm motility, membrane integrity, and DNA stability. Conversely, other materials (e.g., silver nanoparticles, silica nanoparticles) release surface metal ions, activate inflammatory pathways, or impair mitochondrial function, triggering Fenton reactions and excessive ROS accumulation, leading to lipid peroxidation, DNA fragmentation, and reproductive cell apoptosis. Furthermore, the effects of nanomaterials are influenced by their physicochemical characteristics (e.g., size, modification), exposure dose, administration route, and research models. Surface functionalization (e.g., antioxidant loading, polymer coating) can effectively modulate their outcomes. This review emphasizes the need for a careful balance between the antioxidant potential and pro-oxidant risks of nanomaterials in reproductive medicine. Future studies should focus on multi-scale toxicity assessments, standardized model development, and optimized targeted delivery strategies to promote the sustainable application of nanomaterials in male infertility treatment and sperm preservation technologies.