Bioinspired zinc-doped carbon dots protect against polystyrene microplastic-induced spermatogenic dysfunction through Nrf2 activation and cuproptosis suppression

A zinc-doped trifolirhizin-derived carbon dots was developed. • ZnTFZCDs demonstrate favorable biosafety without overt cytotoxicity, hemolysis, or organ damage. • ZnTFZCDs administration ameliorates testicular histopathology, improves sperm count and morphology. • ZnTFZCDs reactivates the Nrf2/HO-1 antioxidant axis, and suppresses cuproptosis-associated alterations in testicular tissues. Polystyrene microplastics (PS-MPs) are increasingly recognized for their detrimental effects on reproductive health, particularly in the male reproductive system. While mitochondrial oxidative stress is recognized as a driver of MPs-induced reproductive injury, it remains unclear whether this process involves cuproptosis, a newly identified copper-dependent form of regulated cell death, and elucidating this potential link is critical for alleviating such damage. Here, we report that PS-MPs exposure induces testicular injury and spermatogenic dysfunction in mice, associated with redox imbalance, copper transport defects, and upregulation of the cuproptosis regulators Ferredoxin 1 (FDX1) and Lipoic Acid Synthetase (LIAS). In turn, zinc-doped trifolirhizin-derived carbon dots (ZnTFZCDs) were rationally designed via a one-step hydrothermal strategy, embedding the antioxidant properties of a natural flavonoid and the reproductive-protective role of zinc into a biocompatible carbon nanoplatform. ZnTFZCDs are well-dispersed carbon dots rich in oxygen/nitrogen-containing groups with Zn coordination, and demonstrate favorable biosafety without overt cytotoxicity, hemolysis, or organ damage. In vitro , ZnTFZCDs potently scavenge intracellular reactive oxygen species (ROS), maintain antioxidant enzyme activities, preserve mitochondrial membrane potential, suppress lipid peroxidation, and rescue Glutathione peroxidase 4 (GPX4) expression in MPs-exposed RAW264.7 and GC-2 cells. Notably, ZnTFZCDs modulate copper homeostasis by upregulating the copper exporter ATP7B, downregulating the importer SLC31A1, and reducing FDX1/LIAS expression, thereby inhibiting cuproptosis-related signaling. In vivo , ZnTFZCDs administration ameliorates testicular histopathology, improves sperm count and morphology, reactivates the Nrf2/HO-1 antioxidant axis, and suppresses cuproptosis-associated alterations in testicular tissues, confirming the translational potential of the in vitro findings. Collectively, ZnTFZCDs represent a bio-inspired nanoplatform that attenuates PS-MPs-induced male reproductive injury through coordinated modulation of redox and copper homeostasis, offering a new therapeutic strategy for environmental pollutant-related reproductive disorders by targeting the previously overlooked cuproptosis pathway. This work reports a novel zinc-doped trifolirhizin-derived carbon dots (ZnTFZCDs) for attenuating PS-MPs-induced male reproductive injury through coordinated restoration of redox and copper homeostasis. Download: Download high-res image (323KB) Download: Download full-size image