Enzyme mimics or artificial enzymes are a class of catalysts that have been actively pursued for decades and have heralded much interest as potentially viable alternatives to natural enzymes. Aside from having catalytic activities similar to their natural counterparts, enzyme mimics have the desired advantages of tunable structures and catalytic efficiencies, excellent tolerance to experimental conditions, lower cost, and purely synthetic routes to their preparation. Although still in the midst of development, impressive advances have already been made. Enzyme mimics have shown immense potential in the catalysis of a wide range of chemical and biological reactions, the development of chemical and biological sensing and anti-biofouling systems, and the production of pharmaceuticals and clean fuels. This Review concerns the development of various types of enzyme mimics, namely polymeric and dendrimeric, supramolecular, nanoparticulate and proteinic enzyme mimics, with an emphasis on their synthesis, catalytic properties and technical applications. It provides an introduction to enzyme mimics and a comprehensive summary of the advances and current standings of their applications, and seeks to inspire researchers to perfect the design and synthesis of enzyme mimics and to tailor their functionality for a much wider range of applications.

Based on the concept of the nanoconfinement reaction, a synthetic strategy is developed to construct carbon-coated iron phosphide (FeP) with an amorphous and mesoporous framework anchored on carbon nanotubes (CNTs). The synthesis involves direct growth of FeOOH on the CNTs followed by silica coating, carbon coating, and subsequent treatments of low-temperature phosphidation and silica removal procedures. During the synthesis, the silica layer is adopted to not only serve as a sacrificial internal spacer to increase the mesoporosity (311 m² g⁻¹ and 0.36 cm³ g⁻¹) of the FeP framework, but also to provide a confined environment in guiding the structural evolution of the homogenous/conformal framework and topologically amorphous nature of FeP. When used as an anode material in sodium-ion batteries (SIBs), the FeP-based electrode shows a utilization rate of 78 % for the active material and a reversible capacity of 415 mAhg⁻¹. Even at a higher current density of 500 mAg⁻¹, a capacity retention rate of 90 % over 500 cycles is obtained with a capacity-decay rate of only 0.02 % per cycle. The much improved performance of the FeP-based electrode in SIBs clearly demonstrates the potential of FeP to be used as the anode material in SIBs when it is engineered in a nanoconfinement environment to overcome its structural constraints. In principle, this strategy can be adapted to engineer other transition-metal phosphide-based materials for energy-storage applications.

A simple and highly sensitive and selective hydrogen sulfide assay utilizing plasmonic nanoprobes is presented in this report. The assay employs the etching of silver in the Ag/Au core–shell nanoprisms, accompanied by surface plasmon resonance (SPR) signal depression and shift. Briefly, thin layers of gold are first coated onto silver nanoprisms. The thin gold layer not only guarantees the high stability of the plasmonic nanoprobes but also ensures the high selectivity toward hydrogen sulfide. Once hydrogen sulfide is introduced, the silver core is converted to Ag₂S mainly from its lateral walls. Moreover, the SPR peak is located in the NIR region that makes these plasmonic nanoprobes more appealing for the detection of hydrogen sulfide in real-world samples and in in vivo applications.

Herein a novel strategy for the construction of an amperometric biosensor for highly sensitive and selective determination of glucose is described. The biosensor is made of a biocomposite membrane of glucose oxidase (GOx) and an Os(bpy)₂ (bpy=2,2′-bipyridine)-based anionic redox polymer (Os-RP) mediator. The biosensor is fabricated through the co-immobilization of GOx and the Os-RP on the surface of a glassy carbon electrode by a simple one-step chemical crosslinking process. The crosslinked Os-RP/GOx composite membrane shows excellent catalytic activity toward the oxidation of glucose. Under optimal experimental conditions, a linear correlation between the oxidation current of glucose in amperometry at 0.25 V (vs. Ag/AgCl) and glucose concentration up to 10 mM with a sensitivity of 16.5 μA mM⁻¹ cm⁻² and a response time <5 s. Due to the presence of anionic sulfonic acid groups in the backbone of the redox polymer, the biosensor exhibits excellent selectivity to glucose in the presence of ascorbic acid and uric acid. The low hydrophobicity of the composite membrane also effectively retards the transport of molecular oxygen within the membrane.