Cerium oxide nanoparticles in vivo distribution and transformation behavior mediate intestinal transit function

CeO₂ nanoparticles (NPs) could be exposed to all levels of food chain organisms during generation or utilization, and the possible effects on intestinal microecosystem by potential human ingestion deserves to be scrutinized. However, the effects of continuous ingestion with CeO₂ NPs on distribution and intestinal physiological function are not known. This work showed the distribution in vivo, and the potential biochemical mechanisms in Ce^3 + /Ce⁴⁺ electron conversion mediated the elimination of reactive oxygen species (ROS) with the co-involvement of intestinal microbes after CeO₂ NPs (10 mg/kg·bw/day, 28 days) continuous ingestion in mice. CeO₂ NPs can be mostly excreted in feces (51.49 %), yet the rest existed at different levels in all tissues, and with the highest levels in digestive tissues (stomach (36.78 %) and intestine (4.44 %)). CeO₂ NPs exhibited higher accumulation in intestine with low transporter capacity and further participate in redox processes, ultimately alleviating transport function disruption. Importantly, electron transfer from Ce³⁺ to Ce⁴⁺ took a major role in H₂O₂ to H₂O production, where the H₂O₂ level was reduced by 32.92 %. Further, CeO₂ NPs electron transfer reduced intestinal microbial extracellular oxidase combinatorial role in ROS. These results suggested that after CeO₂ NPs ingestion, electron transfer between Ce³⁺ and Ce⁴⁺ modulates the intestinal redox microcosm and mitigates the reduction of persistent transport capacity. Therefore, this work provides more accurate descriptions of the entire physiological process of CeO₂ NPs after ingestion, spotlights their intestinal transport fate and redox functional effects, and opens up new theoretical perspectives for potential human health studies of NPs.