Tailor-Made Synthesis of Cerium Oxide Nanoparticles for Improving the Skin Decontamination of Paraoxon

Abstract

CeO 2 nanoparticles possess catalytic activity for hydrolysis of organophosphates such as paraoxon and nerve agents used in chemical warfare. Intoxication with these highly toxic compounds can occur directly through inhalation or dermal contact and lead to rapid and severe consequences including death. It is therefore necessary to have effective means of skin decontamination, and CeO 2 nanoparticles are promising. In this study, a wide range of CeO 2 nanoparticles were synthesized and their efficiency against paraoxon degradation was evaluated. Nanocubes (NC), nanorods (NR), nano-octahedra (NO), and nanopolyhedra (NPO) were studied along with nanoparticles obtained after calcination (NC*, NR*, NO*, and nanotruncated octahedra NTO*). Results show an influence of calcination, specific surface area, and crystal facets with higher activity for {111} facets compared to {100} facets. pH also impacted POX degradation rates, with higher pH accelerating the degradation. In vitro tests using the Franz cell method demonstrated the skin decontamination efficacy of the CeO 2 nanoparticles. NC* exhibited lower efficiency, possibly due to smaller surface area and limited {100} facet degradation. The most efficient nanoparticles were NR* and NO* followed by NTO* consistently with their degradation efficiency and specific surface area. Notably, NR* and NO* performed comparably to FE (Fuller's earth), the standard powder skin decontaminant on battlefield. Unlike FE that can only adsorb paraoxon, CeO 2 nanoparticles can neutralize it into safer byproducts. This study highlights the interest of CeO 2 nanoparticles and the influence of their physicochemical properties on organophosphorus compound degradation and cutaneous decontamination.