Nanoplastics and chain-length-dependent PFCs disrupt reproductive endocrinology by targeting the PKC - GnRH signaling axis

Nanoplastics (NPs) and microplastics (MPs) are widespread in aquatic ecosystems and frequently co-occurred with perfluorinated compounds (PFCs), yet their combined toxic effects remain poorly understood. Here, we investigated the combined toxicity of both nano- and micro-sized polystyrene (PS) and two PFCs [perfluorooctanesulphonic acid (PFOS) and perfluorobutane sulfonate (PFBS)] to Brachionus calyciflorus. PFOS exerted markedly higher toxicity effects than PFBS. Both nano-sized (50 nm) and micro-sized (1 μm) PS were examined, and the results showed that particle size strongly modulated toxic outcomes, with nanoplastics producing more pronounced effects than microplastics. Co-exposure to nanoplastics significantly enhanced PFOS reproductive toxicity by promoting oxidative stress and altering reproductive modes, whereas PS combined with PFBS showed no significant synergistic toxicity. Transcriptomic and molecular docking analyses further revealed that both PFOS and PFBS targeted protein kinase C (PKC), implicating disrupted calcium signaling and mitochondrial function as key drivers of reproductive impairment. These findings reveal a novel mode of reproductive toxicity induced by PFCs in invertebrates and highlight the importance of monitoring emerging fluorinated contaminants in combination with nanoplastics.