CeO_2−x nanorods with intrinsic urease-like activity

Abstract

The large-scale production and ecotoxicity of urea make its removal from wastewater a health and environmental challenge. Whereas the industrial removal of urea relies on hydrolysis at elevated temperatures and high pressure, nature solves the urea disposal problem with the enzyme urease under ambient conditions. We show that CeO2-x nanorods (NRs) act as the first and efficient green urease mimic that catalyzes the hydrolysis of urea under ambient conditions with an activity (kcat = 9.58 × 101 s-1) about one order of magnitude lower than that of the native jack bean urease. The surface properties of CeO2-x NRs were probed by varying the Ce4+/Ce3+ ratio through La doping. Although La substitution increased the number of surface defects, the reduced number of Ce4+ sites with higher Lewis acidity led to a slight decrease of their catalytic activity. CeO2-x NRs are stable against pH changes and even to the presence of transition metal ions like Cu2+, one of the strongest urease inhibitors. The low costs and environmental compatibility make CeO2-x NRs a green urease substitute that may be applied in polymer membranes for water processing or filters for the waste water reclamation. The biomimicry approach allows the application of CeO2-x NRs as functional enzyme mimics where the use of native or recombinant enzyme is hampered because of its costs or operational stability.

Antioxidant activity of cerium dioxide nanoparticles and nanorods in scavenging hydroxyl radicals

“…Details about the CeNRs can be found from our previous study. 32 In addition to the detection of size and morphology, the specic surface areas of the cerium nanoparticles were determined to be 24.8 AE 0.4 m 2 g À1 (B 50 nm CeNPs) ( Fig. 1D), 39.2 AE 0.7 m 2 g À1 (B 25 nm CeNPs) ( Fig.…”

“…This implies that the amount of $OH decreases accordingly. Based on the spin-counting method, 32 we quantied the concentration of BMPO-OH in these solutions. The results are shown in Fig.…”

Micro‐Bio‐Chemo‐Mechanical‐Systems: Micromotors, Microfluidics, and Nanozymes for Biomedical Applications

“…The catalytic efficiencies of nanozymes in most cases are lower than that of natural enzymes. For example, CeO 2− x nanorods, [ 145 ] can act as an efficient green urease mimics that catalyzes the hydrolysis of urea under ambient conditions with a turnover number k cat of 9.58 × 10 1 s −1 , which is significantly lower than that of native jack bean urease. In some cases, however, nanozymes have been reported to have catalytic efficiencies comparable to that of natural enzymes.…”

CeO2 Nanoparticle-Containing Polymers for Biomedical Applications: A Review

“…Phua et al observed that proteolytic enzyme urease degraded segmented, cross-linked medical polyester Biomer ® at 37 • C in vitro after just a few months. Recently, Korschelt et al demonstrated the urease-like activity of ceria nanorods [106], which suggests the possibility of controlling the rate of degradation of polyurethane items in the body by ceria nanoparticles.…”