Enhanced uranium sequestration through selenite-modified nano-chitosan loaded with melatonin: Facilitating U(IV) conversion

The combined chemotoxicity and radiotoxicity associated with uranium, utilized in nuclear industry and military applications, poses significant threats to human health. Among uranium pollutants, uranyl is particularly concerning due to its high absorptivity and potent nephrotoxicity in its + 6 valence state. Here, we have serendipitously found Na 2 SeO 3 facilitates the conversion of U(VI) to U(IV) precipitates. A novel approach involving nano-chitosan loaded internally with melatonin and externally modified with selenite (NPs Cs-Se/MEL) was introduced. This modification not only enhances the conversion of U(VI) to U(IV) but also preserves the spherical nanostructure and specific surface area, leading to increased adsorption of U(VI) compared to unmodified samples. Selenite modification improves lysosomal delivery in HEK-293 T cells and kidney distribution of the nanoparticles. Furthermore, NPs Cs-Se/MEL demonstrated a heightened uranium concentration in urine and exhibited remarkable efficiency in uranium removal, resulting in a reduction of uranium deposition in serum, kidneys, and femurs by up to 52.02 %, 46.79 %, and 71.04 %, respectively. Importantly, NPs Cs-Se/MEL can be excreted directly from the kidneys into urine when carrying uranium. The results presented a novel mechanism for uranium adsorption, making selenium-containing nano-materials attractive for uranium sequestration and detoxification.