Catalytic performance of ceria fibers with phosphatase-like activity and their application as protein carriers

Ceria (CeO2) synthesized by cerium nitrate hexahydrate in alkaline solution under hydrothermal treatment produces a fiber structure that allows high O-P bond cleavage activity. Brunauer-Emmett-Teller (BET) analysis revealed that fiber-morphological CeO2 with high surface area (73.9 m(2)/g) and pore volume (0.42 cm(3)/g) showed better hydrolytic activity than nanopolyhedral and cubic morphologies. The CeO2 fiber displayed hydrolytic activity in a tris(hydroxymethyl)aminomethane (Tris) buffer; however, no reaction occurred in a phosphate buffer. From analysis by based on scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDX), the phosphate group in the buffer was seen to be immediately adsorbed on the surface of CeO2 particles; therefore, the CeO2 catalysts could not attack the phosphoric esters as a substrate. In addition, the CeO2 fiber showed hydrolytic activity for deoxyribonucleic acid (DNA). Moreover, enzymes loaded on the CeO2 fiber particles retained activity levels equivalent to free-solution enzymes. It is thought that the findings of the present study regarding the properties of CeO2 fiber will have a significant impact in the fields of not only antibacterial and antimicrobial reagents, but also biosensors and biocatalysts. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.