Nanozymes have advantages over natural enzymes, such as facile production on large scale, long storage time, low costs, and high stability in harsh environments. Carbon nanomaterials (CNMs), including fullerenes, carbon nanotubes, graphene, carbon quantum dots, and graphene quantum dots, have become a star family in materials science. As a new class of nanozymes, the catalytic activity of CNMs and their hybrids has been extensively reported. In this Minireview, recent progress of CNMs based artificial enzymes, focusing on those with peroxidase-like activity, has been summarized. The enzymatic properties, catalytic mechanisms, and novel applications of CNM nanozymes in sensing, therapy, and environmental engineering are discussed in detail. Additionally, we also highlight the remaining challenges and unsolved problems. With the fast development of bionanotechnology, the unique enzymatic properties and advantages of CNM nanozymes have received much attention and will continue to be an active and challenging field for the years to come.

Carbon Nanozymes: Enzymatic Properties, Catalytic Mechanism, and Applications.

Biological materials have robust hierarchical structures capable of specialized functions and the incorporation of natural biologically active components, which have been finely tuned through millions of years of evolution. These highly efficient architectural designs afford remarkable transport and mechanical properties, which render them attractive candidates for flexible electronic sensing technologies. This review provides a comprehensive overview of the fundamental aspects and applications of biological materials for flexible electronic devices and discusses various classes of biological materials by describing their unique structures and functions. We discuss the effect of the biological activity of biological materials on the improved properties in detail, because this effect overcomes the limited bioavailability and restricted morphology of materials generally encountered in traditional flexible electronic devices. We also summarize various approaches for the design and functionalization of natural materials and their applications in flexible electronic devices for use in biomedical, electron, energy, environmental and optical fields. Finally, we provide new insights and perspectives to further describe trends for future generations of biological materials, which are likely to be critical components (building blocks or elements) in future flexible electronics.

New insights and perspectives into biological materials for flexible electronics

Nitrogen-doped carbon dots originating from unripe peach for fluorescent bioimaging and electrocatalytic oxygen reduction reaction

Freeze casting – A review of processing, microstructure and properties via the open data repository, FreezeCasting.net

Low photocatalytic efficiency of visible light and fast recombination of photo-generated carriers are two challenges facing the applications of photocatalyst sterilant zinc oxide (ZnO). Meanwhile, both light and dark photocatalytic activities are important. It is of great theoretical and practical significance to construct a day-night photocatalytic antibacterial material, which is beneficial to the effective use of energy and to tackle the limitation of using photocatalytic bacteriostat. ZnO nanoflowers decorated vanadium pentoxide (V2O5) nanowires heterojunction (ZVH) was firstly fabricated using a facile water-bathing method. The designed ZVH structure efficiently produced abundant reactive oxygen species (ROS) in both light and darkness. It yielded 99.8% and 99.0% of antibacterial rate against S. aureus due to oxidative stress induced by ROS in light and darkness, respectively. The generation of ROS played a major role in the antibacterial activities against S. aureus under both light and dark conditions. The prepared ZVH with improved antibacterial properties provides an alternative for day-night antibacterial agents.

Zinc oxide/vanadium pentoxide heterostructures with enhanced day-night antibacterial activities.

Preparation of Co3O4/crumpled graphene microsphere as peroxidase mimetic for colorimetric assay of ascorbic acid

The hierarchical urchin-like NiCo 2 O 4 microspheres were successfully fabricated by facile two-step method, including template-free hydrothermal and calcination. The prepared NiCo 2 O 4 microspheres with amounts of absorbed oxygen were found to possess oxidase-like activity. They could catalytically oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) without the exogenous addition of H 2 O 2 , causing typical color reaction. But hydroquinone (HQ) could induce the reduction of oxTMB and result in a conspicuous blue color fading. In this paper, a simple and rapid colorimetric method for detecting trace amount of HQ was explored in-depth. Excellent linear relationship (5–110 μM) and a low detection limit of 2.7 μM were achieved. Meaningfully, this method could be well applied in real environmental samples with outstanding recoveries ranging from 97.07% to 103.52%. These primary results demonstrated that the NiCo 2 O 4 microspheres have a great potential for applications in environmental chemistry.

Facile preparation of urchin-like NiCo2O4 microspheres as oxidase mimetic for colormetric assay of hydroquinone

Synthesis of 3D hierarchical porous Co3O4 film by eggshell membrane for non-enzymatic glucose detection

A novel 3D chitosan/multiwalled carbon nanotubes (CNTs) aerogel with snubby CNTs tips emerged on the surface of soft nanosheets was synthesized by ice-templating method. The ideal cooperative effect of phragmoid CS and electrical CNTs offered synthetical properties, such as low density (about 6.3 mg cm −3 ), flexibility, absorption, catalysis capacities, improved electrochemical characteristics and novel applications. This unique architecture showed good specificity to dopamine with ultralow detection limit of 0.3 nM in biosensing applications. Meanwhile, the unique surface of soft nanosheets with snubby CNTs tips makes it an incubative bed for in situ adsorbed growth of nanostructures. Cu 2 O@CuO chipped core-shell nanoparticles were in situ grown onto the soft nanosheets by simple adsorption of Cu 2+ and used for non-enzymatic detection.

Sisi Fan

Papers

Preparation of Co3O4/crumpled graphene microsphere as peroxidase mimetic for colorimetric assay of ascorbic acid

Facile preparation of urchin-like NiCo2O4 microspheres as oxidase mimetic for colormetric assay of hydroquinone

Synthesis of 3D hierarchical porous Co3O4 film by eggshell membrane for non-enzymatic glucose detection

Flexible chitosan/carbon nanotubes aerogel, a robust matrix for in-situ growth and non-enzymatic biosensing applications

Self-assembled NiFe 2 O 4 /carbon nanotubes sponge for enhanced glucose biosensing application