Robust and Reusable Laccase Mimetic Copper Oxide Nanozyme for Phenolic Oxidation and Biosensing

Abstract

The development of earth-abundant metal-oxidebased nanomaterials with an intrinsic enzyme-mimicking activity (nanozyme) is useful for both practical applications and fundamental research. The laccase enzyme is a multicopper oxidase that finds commercial utility in environmental remediation and biotechnology, but with significant limitations under harsh conditions. Herein, we present the laccase-like activity of Cu 2 O nanospheres, fabricated using a one-pot polyol-based microwaveassisted method. The as-synthesized Cu 2 O nanospheres possess great stability under harsh conditions and exhibit excellent laccaselike activity with a K M value of 0.2 mM, considerably smaller than those of previously reported nanozymes as well as native laccase. The utility of the nanozyme was demonstrated in the efficient oxidation of phenolic pollutants under real-life high-salinity conditions, as well as in the colorimetric detection of biomolecules such as epinephrine and dopamine with sensitivities of 10 and 6.5 μM, respectively. Notably, the Cu 2 O nanozyme enabled naked-eye detection of the acetylcholinesterase enzyme with a biorelevant sensitivity (2.5 pM). This robust and recyclable laccase-mimicking nanozyme introduces a simple and cost-effective metal oxide platform that would find multiple practical applications in environmental remediation, catalysis, and biosensing.

Facile Fabrication of 1-Methylimidazole/Cu Nanozyme with Enhanced Laccase Activity for Fast Degradation and Sensitive Detection of Phenol Compounds

“…Most of the phenolic compounds in the environment are derived from pulp mills, coal mines, refineries, wood preservation factories and various chemical industries [ 30 , 31 ]. Many methods have been tested for phenolic compounds treatment or degradation including photocatalysis [ 32 ], biocatalysis [ 33 ], nanozyme [ 34 ], thermal catalysis [ 35 ] and adsorption [ 36 ]. Although natural laccase can be used as a green biocatalyst for sewage treatment and soil remediation [ 37 , 38 ], it has some disadvantages including high cost, easy inactivation and poor stability, which seriously limit the practical application [ 39 ].…”

“…Recently, nanozymes with laccase-like activity have been used in phenolic pollutant degradation. For instance, the composite of Cu/His-Cys formed by the assembly of copper with histidine and lysine was proved to have good laccase-like activity [ 40 ], Cu-GMP (Cu-guanosine monophosphate) with non-static MOF structure catalyzes the oxidation of phenolic species faster than laccase [ 5 ], Cu 2 O nanoparticles with laccase-like activity exhibit good cycling ability [ 34 ] and I-Cu (imidazole-Cu) [ 41 ] with the structure of open vesicles exhibits laccase-like activity and strong stability. Despite the fact that these nanozymes have good laccase mimetic properties, they have the disadvantages of expensive raw materials (such as dipeptides), general activity and irregular shapes.…”

Porous, Oxygen Vacancy Enhanced CeO2–x Microspheres with Efficient Enzyme-Mimetic and Photothermal Properties

“…On the other hand, transition metal oxide nanoparticles, noble metal nanoparticles, and carbon-based nanomaterials have been also used as nanozymes that mimick the catalytic activities of peroxidase, oxidase, SOD, reductase, catalase, and hydrolase. − Nanozymes with different enzyme-mimetic behaviors have been evaluated in various sustainable applications such as biosensing, diagnostics, synergistic therapy of cancer, and detection of disease biomarkers and pollutants. − Superparamagnetic nanozymes were also used for the detection of glucose, disease-specific biomarkers, and exosomes. − …”

Temporally Controlled Multienzyme Catalysis Using a Dissipative Supramolecular Nanozyme

“…The development of nanozymes displaying multienzymatic activities including oxidases and peroxidases has primarily focused on micro/nanostructures of metals, metal oxides, and metal–organic frameworks. − Different facet-controlled transition metal oxides and iron oxides are the typical choices for fabricating multienzymatic nanozymes. , Despite efficient catalytic activities of these materials, significant heterogeneities of the structures, multistep synthetic procedures, limited active sites, and nondynamic nature restrict achieving their full potential in different applications including creating artificial life. Recently, based on their structurally dynamic nature, supramolecular nanozymes with complex and hierarchical architectures have attracted considerable attention in developing enzyme mimics for practical applications .…”