Resolving polymeric nanoplastics in human cumulus cells by synchrotron X-ray fluorescence and light nano-imaging.

Micro- and nanoplastics have been shown to cross biological barriers, reach the female reproductive tract, and infiltrate ovarian tissue, raising critical concerns about their potential impact on reproductive health and early-life outcomes. Elucidating how nanoplastics interact with ovarian cells is therefore essential for risk assessment, but requires ultra-sensitive analytical approaches capable of resolving rare events at the nanoscale. Detecting individual polymeric nanoplastics within structurally preserved human cells remains a major challenge due to their low abundance, small size, and embedding within complex biological matrices, particularly in sensitive systems where they may act as vectors for environmental contaminants. Here, we investigated cadmium selenide quantum dot-labeled polyethylene nanoplastics in human cumulus cells using a strategy combining spectral confocal microscopy and synchrotron-based X-ray fluorescence nano-imaging. Spectral imaging enabled discrimination of nanoparticle-associated signals and guided region-of-interest selection under low-occupancy nanoplastic conditions, while XRF at 100 nm resolution resolved discrete cadmium-enriched hotspots consistent with spatially confined nanoplastic-associated Cd hotspots. By simultaneously mapping endogenous elements, this approach provides elemental context within structurally preserved cells and further establishes synchrotron X-ray nano-imaging as an advantageous technique to support future investigations of early-life exposure scenarios.