Cobalt Phosphate Nanocrystals: A Catalase-Like Nanozyme and In Situ Enzyme-Encapsulating Carrier for Efficient Chemoenzymatic Synthesis of α-Keto Acid

One-pot chemo- and photo-enzymatic linear cascade processes

The combination of chemo- and photocatalyses with biocatalysis, which couples the flexible reactivity of the photo- and chemocatalysts with the highly selective and environmentally friendly nature of enzymes in one-pot linear cascades, represents a powerful tool in organic synthesis. However, the combination of photo-, chemo- and biocatalysts in one-pot is challenging because the optimal operating conditions of the involved catalyst types may be rather different, and the different stabilities of catalysts and their mutual deactivation are additional problems often encountered in one-pot cascade processes. This review explores a large number of transformations and approaches adopted for combining enzymes and chemo- and photocatalytic processes in a successful way to achieve valuable chemicals and valorisation of biomass. Moreover, the strategies for solving incompatibility issues in chemo-enzymatic reactions are analysed, introducing recent examples of the application of non-conventional solvents, enzyme-metal hybrid catalysts, and spatial compartmentalization strategies to implement chemo-enzymatic cascade processes.

Co-based Nanozymatic Profiling: Advances Spanning Chemistry, Biomedical, and Environmental Sciences

Nanozymes, next-generation enzyme-mimicking nanomaterials, have entered an era of rational design; among them, Co-based nanozymes have emerged as captivating players over times. Co-based nanozymes have been developed and have garnered significant attention over the past five years. Their extraordinary properties, including regulatable enzymatic activity, stability, and multifunctionality stemming from magnetic properties, photothermal conversion effects, cavitation effects, and relaxation efficiency, have made Co-based nanozymes a rising star. This review presents the first comprehensive profiling of the Co-based nanozymes in the chemistry, biology, and environmental sciences. The review begins by scrutinizing the various synthetic methods employed for Co-based nanozyme fabrication, such as template and sol-gel methods, highlighting their distinctive merits from a chemical standpoint. Furthermore, a detailed exploration of their wide-ranging applications in biosensing and biomedical therapeutics, as well as their contributions to environmental monitoring and remediation is provided. Notably, drawing inspiration from state-of-the-art techniques such as omics, a comprehensive analysis of Co-based nanozymes is undertaken, employing analogous statistical methodologies to provide valuable guidance. To conclude, a comprehensive outlook on the challenges and prospects for Co-based nanozymes is presented, spanning from microscopic physicochemical mechanisms to macroscopic clinical translational applications.

A chemo-biocatalyst based on glutamate oxidase-integrated biomimetic trimanganese tetraoxide as cascade composite nano-catalyst for synthesis of α‑Ketoglutaric acid

The combination of chemo- and biocatalysts to perform one-pot synthetic route has presented great challenges for decades. Herein, glutamate oxidase (GLOX) and trimanganese tetraoxide (Mn3O4) nanocrystals were combined for the first time by one-step biomineralization to construct a mimic multi-enzyme system (GLOX@Mn3O4) for chemoenzymatic synthesis of α‑ketoglutaric acid (α‑KG). Mn3O4 not only served as a support for the enzyme immobilization, but also contributed its catalytic activity to co-operate with natural enzymes for the cascade reactions. The as-synthesized chemo-enzyme catalysts with directly contacted catalytic sites of the enzyme and inorganic catalyst maximizes the substrate channeling effffects for in situ rapid decomposition of the oxidative intermediate, H2O2, during the enzymatic oxidation of sodium glutamate, thus relieving the inhibition of H2O2 accumulation for GLOX. Benefiting from the excellent stability and reusability of GLOX@Mn3O4, a nearly 100% conversion (99.7%) of l-glutamate to α-KG was achieved, over 4.7 times higher than that of the free GLOX system (21.2%). This work provides a feasibility for constructing a high-performance chemo-enzyme catalyst for cascade catalysis, especially for those reactions with toxic intermediates.

Multienzyme-Mimicking LaCoO3 Nanotrigger for Programming Cancer-Cell Pyroptosis

Pyroptosis, a distinct paradigm of programmed cell death, is an efficient strategy against cancer by overcoming resistance to apoptosis. In this study, LaCoO3 (LCO) lanthanide-based nanocrystals with multienzyme characteristics are rationally designed and engineered to trigger the generation of cytotoxic reactive oxygen species (ROS) and the release of lanthanum ions, ultimately inducing lung cancer cell pyroptosis. The peroxidase- and oxidase-mimicking activities of LCO nanocrystals endow LCO with ROS production capacity in tumor tissues with an acidic pH and high hydrogen peroxide content. Concurrently, the LCO nanoenzyme exhibits catalase- and glutathione peroxidase-like activities, reversing the hypoxic microenvironment, destroying the activated antioxidant system of tumor cells, and amplifying the sensitivity of tumor cells to ROS. The use of ultrasound further accelerates the enzymatic kinetic rate. Most importantly, the La3+ ions released by LCO robustly destroy the lysosomal membrane, finally inducing canonical pyroptotic cell death, together with ROS. LCO-nanocrystal-triggered programmed cell pyroptosis amplifies the therapeutic effects both in vitro and in vivo, effectively restraining lung cancer growth and metastasis. This study paves a new avenue for the efficient treatment of lung cancer and metastasis through US-enhanced lanthanum-based nanoenzyme platforms and pyroptotic cell death.

Cobalt-Nitrogen Co-Doped Carbon as Highly Efficient Oxidase Mimics for Colorimetric Assay of Nitrite

Transition metal-N-doped carbon has been demonstrated to mimic natural enzyme activity; in this study, cobalt-nitrogen co-doped carbon (Co-N-C) nanomaterial was developed, and it could be an oxidase mimic. Firstly, Co-N-C with oxidase-like activity boosts the chromogenic reaction of 3,3',5,5'-tetramethylbenzidine (TMB) to produce the oxidized TMB (oxTMB). And the aromatic primary amino group of oxTMB reacts with nitrite (NO₂^-) to form diazo groups. Based on this background, we developed a cascade system of a Co-N-C-catalyzed oxidation reaction and a diazotization reaction for nitrite determination. The low detection limit (0.039 μM) indicates that Co-N-C is superior compared with the vast majority of previously reported nitrite assays. This study not only provides a novel nanozyme with sufficiently dispersed active sites, but it also further applies it to the determination of nitrite, which is expected to expand the application of nanozymes in colorimetric analysis.

Recent advances in colorimetric sensors based on nanozymes with peroxidase-like activity

Nanozymes have been widely used to construct colorimetric sensors due to their advantages of cost-effectiveness, high stability, good biocompatibility, and ease of modification. The emergence of nanozymes greatly enhanced the detection sensitivity and stability of the colorimetric sensing platform. Recent significant research has focused on designing various sensors based on nanozymes with peroxidase-like activity for colorimetric analysis. However, with the deepening of research, nanozymes with peroxidase-like activity has also exposed some problems, such as weak affinity and low catalytic activity. In view of the above issues, existing investigations have shown that the catalytic properties of nanozymes can be improved by adding surface modification and changing the structure of nanomaterials. In this review, we summarize the recent trends and advances of colorimetric sensors based on several typical nanozymes with peroxidase-like activities, including noble metals, metal oxides, metal sulfides/metal selenides, and carbon and metal-organic frameworks (MOF). Finally, the current challenges and prospects of colorimetric sensors based on nanozymes with peroxidase-like activity are summarized and discussed to provide a reference for researchers in related fields.

ε-Polylysine-Based Macromolecules with Catalase-Like Activity to Accelerate Wound Healing by Clearing Bacteria and Attenuating Inflammatory Response

Wound healing has remained a critical challenge due to its susceptibility to bacterial infection and the unique biological inflammatory response. Safe and effective therapeutics are still lacking. Biodegradable macromolecules (ε-polylysine-g-ferrocene, EPL-g-Fc) were developed to accelerate wound healing by combating bacterial infection and attenuating inflammatory responses. The biodegradable macromolecules were prepared via a Schiff-based reaction between ferrocene carboxaldehyde (Fc) and ε-polylysine (EPL). Through the synergistic combination of positive-charged EPL and π-π stacked Fc, the macromolecules possess excellent antibacterial activities. EPL-g-Fc with catalase-like activity could modulate the oxidative microenvironment in mammalian cells and zebrafish by catalyzing H₂O₂ into H₂O and O₂. EPL-g-Fc could alleviate inflammatory response in vitro. Furthermore, the macromolecules could accelerate bacteria-infected wound healing in vivo. This work provides a versatile strategy for repairing bacteria-infected wounds by eliminating bacteria, modulating oxidative microenvironment, and alleviating inflammatory response.