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

Abstract

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 m2/g) and pore volume (0.42 cm3/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.