Confocal Surface-enhanced Raman Imaging of the Intestine Barrier Crossing Behavior of Dual-functional Plasmonic Nanoplastics in Daphnia magna

Due to wide spread, high concentrations, and easy bioavailability, nanoplastics (nPs) pose great ecological hazards both in the marine and freshwater ecosystems. To evaluate their impacts on the model water flea, Daphnia magna, and how they translocate from the intestine, the primary organ of accumulation, to the other body parts, is a key subject of research. In our current effort, we addressed the phenomenon of inter organ translocation of the nPs and suggested plausible mechanism of the process with the help of a dual functional plasmonic polystyrene (PS) nanoplastic (nPS) and confocal Raman mapping. We synthesized a ‘core-shell' polystyrene coated-nano gold particle and conjugated it with a Raman reporter, 4-mercapto benzoic acid (4-MBA). This dual functional plasmonic nanoplastic (model nPS) fulfills the purpose of nP as well as surface-enhanced Raman scattering (SERS) nano-probe for imaging. Upon exposure, the Daphnia showed uptake of the model nPSs mainly in the intestine tract. Exposure, beyond 4 h at concentration of 10 mg/L, exhibited inter organ translocation of the model nPSs to other parts in Daphnia body. Translocation was observed with the help of multilayer stack Raman mapping of the SERS signals coming from the model nPSs.