The Fe‐N‐C Nanozyme with Both Accelerated and Inhibited Biocatalytic Activities Capable of Accessing Drug–Drug Interactions

A Molybdenum Disulfide Nanozyme with Charge-Enhanced Activity for Ultrasound-Mediated Cascade-Catalytic Tumor Ferroptosis

The deficient catalytic activity of nanozymes and insufficient endogenous H₂ O₂ in the tumor microenvironment (TME) are major obstacles for nanozyme-mediated catalytic tumor therapy. Since electron transfer is the basic essence of catalysis-mediated redox reactions, we explored the contributing factors of enzymatic activity based on positive and negative charges, which are experimentally and theoretically demonstrated to enhance the peroxidase (POD)-like activity of a MoS₂ nanozyme. Hence, an acidic tumor microenvironment-responsive and ultrasound-mediated cascade nanocatalyst (BTO/MoS₂ @CA) is presented that is made from few-layer MoS₂ nanosheets grown on the surface of piezoelectric tetragonal barium titanate (T-BTO) and modified with pH-responsive cinnamaldehyde (CA). The integration of pH-responsive CA-mediated H₂ O₂ self-supply, ultrasound-mediated charge-enhanced enzymatic activity, and glutathione (GSH) depletion enables out-of-balance redox homeostasis, leading to effective tumor ferroptosis with minimal side effects.

Rational construction of a robust metal-organic framework nanozyme with dual-metal active sites for colorimetric detection of organophosphorus pesticides

While nanomaterials with enzyme-mimicking activities are emerging as promising candidates in the colorimetric detection of organophosphorus pesticides (OPs), the catalytic activities and recognition ability to analyte of most nanozymes are inherently deficient. In this work, we introduced manganese ions into a typical iron based MOF (Fe-MIL(53)) via a one-pot hydrothermal reaction strategy, which brought out a catalytically favorable bimetallic Mn/Fe-MIL(53) MOF nanozyme. The catalytic performance of Mn/Fe-MIL(53) is superior to that of pure Fe-MIL (53) and the mechanism for superior catalytic activity of material is revealed by active species scavenging experiments and X-ray photoelectron spectroscopy (XPS). Besides, the introduction of manganese endows the material with the characteristic of being specially destroyed by choline, which motivates the establishment of a simple, selective and sensitive colorimetric strategy for OPs detection. The proposed colorimetric strategy could quantify the methyl parathion and chlorpyrifos in the concentration range of 10-120 nM and 5-50 nM, respectively. The low detection limit of 2.8 nM for methyl parathion and 0.95 nM (3 S/N) for chlorpyrifos were achieved. Good recoveries were obtained when applied in the real sample detection. Our work paves the way to boost catalytic performance of MOF nanozymes, which will be useful in biosensing.

Fe-Curcumin Nanozyme-Mediated Reactive Oxygen Species Scavenging and Anti-Inflammation for Acute Lung Injury

Pneumonia, such as acute lung injury (ALI), has been a type of lethal disease that is generally caused by uncontrolled inflammatory response and excessive generation of reactive oxygen species (ROS). Herein, we report Fe-curcumin-based nanoparticles (Fe-Cur NPs) with nanozyme functionalities in guiding the intracellular ROS scavenging and meanwhile exhibiting anti-inflammation efficacy for curing ALI. The nanoparticles are noncytotoxic when directing these biological activities. Mechanism studies for the anti-inflammation aspects of Fe-Cur NPs were systematically carried out, in which the infected cells and tissues were alleviated through downregulating levels of several important inflammatory cytokines (such as TNF-α, IL-1β, and IL-6), decreasing the intracellular Ca2+ release, inhibiting NLRP3 inflammasomes, and suppressing NF-κB signaling pathways. In addition, we performed both the intratracheal and intravenous injection of Fe-Cur NPs in mice experiencing ALI and, importantly, found that the accumulation of such nanozymes was enhanced in lung tissue (better than free curcumin drugs), demonstrating its promising therapeutic efficiency in two different administration methods. We showed that the inflammation reduction of Fe-Cur NPs was effective in animal experiments and that ROS scavenging was also effectively achieved in lung tissue. Finally, we revealed that Fe-Cur NPs can decrease the level of macrophage cells (CD11bloF4/80hi) and CD3+CD45+ T cells in mice, which could help suppress the inflammation cytokine storm caused by ALI. Overall, this work has developed the strategy of using Fe-Cur NPs as nanozymes to scavenge intracellular ROS and as an anti-inflammation nanodrugs to synergistically cure ALI, which may serve as a promising therapeutic agent in the clinical treatment of this deadly disease. Fe-Cur NP nanozymes were designed to attenuate ALI by clearing intracellular ROS and alleviating inflammation synergistically. Relevant cytokines, inflammasomes, and signaling pathways were studied.

Cascaded Nanozyme System with High Reaction Selectivity by Substrate Screening and Channeling in a Microfluidic Device

Surpassing natural enzymes in cost, stability and mass production, nanozymes have attracted wide attention in fields from disease diagnosis to tumor therapy. However, nanozymes intrinsically have low reaction selectivity, which significantly restricts their applications. A general method is reported to address this challenge by following a biomimetic operation principle of substrates channeling and screening. Two oxidase- and peroxidase-like nanozymes (i.e., emerging N-doped carbon nanocages and Prussian blue nanoparticles), were cascaded as a proof of concept to improve the reaction selectivity in transforming the substrate into the targeted product by more than 2000 times. The cascaded nanozymes were also adopted to a spatially confined microfluidic device, leading to more than 100-fold enhancement of the reaction efficiency due to signal amplification.

A Titanium Nitride Nanozyme for pH-Responsive and Irradiation-Enhanced Cascade-Catalytic Tumor Therapy

Nanozyme-based catalytic tumor therapy is an emerging therapeutic method with high reactivity in response to tumor microenvironments (TMEs). To overcome the current limitations of deficient catalytic activity of nanozymes, we studied the contributing factors of enzymatic activity based on non-metallic-atom doping and irradiation. Nitrogen doping significantly enhanced the peroxidase activity of Ti-based nanozymes, which was shown experimentally and theoretically. Based on the excellent NIR-adsorption-induced surface plasmon resonance and photothermal effect, the enzymatic activity of TiN nanoparticles (NPs) was further improved under NIR laser irradiation. Hence, an acidic TME-responsive and irradiation-mediated cascade nanocatalyst (TLGp) is presented by using TiN-NP-encapsulated liposomes linked with pH-responsive PEG-modified glucose oxidase (GOx). The integration of pH-responsive GOx-mediated H₂ O₂ self-supply, nitrogen-doping, and irradiation-enhanced enzymatic activity of TiN NPs and mild-photothermal therapy enables an effective tumor inhibition by TLGp with minimal side effects in vivo.

Fe/N co-doped mesoporous carbon derived from cellulose-based ionic liquid as an efficient heterogeneous catalyst toward nitro aromatic compound reduction reaction

Iron and nitrogen-doped carbon substances with abundant active sites that related to dispersion of heteroatom species (Fe and N) on the surface of carbonous structure, are promising choice for eco-friendly catalytic reactions. Herein, cellulose-based ionic liquid (IL) derivative not only employed as the both nitrogen and iron heteroatom precursors, but also has been used as the green and biodegradable substrate. The non-noble Fe-NC@550, was successfully fabricated by convenient carbonization of cellulose-based IL. Further, the FeCl₄^- anion was used as the iron precursor and also it has been applied to elevate the SSA (specific surface area) of catalyst (from 40.96 to 160.42 m²/g) due to the presence of chlorine. On the basis of several pertinent physicochemical and experimental outcomes, the structure of the catalyst was successfully proved in different synthetic steps. As expected, the Fe-NC@550 exhibited the substantial efficiency toward hydrogenation of nitroarenes with high TOF value and also remarkable reusability.

Engineering Fe-N Doped Graphene to Mimic Biological Functions of NADPH Oxidase in Cells

NADPH oxidase (NOX) as a transmembrane enzyme complex controls the generation of superoxide that plays important roles in immune signaling pathway. NOX inactivation may elicit immunodeficiency and cause chronic granulomatous disease (CGD). Biocompatible synthetic materials with NOX-like activities would therefore be interesting as curative and/or preventive approaches in case of NOX deficiency. Herein, we synthesized a Fe-N doped graphene (FeNGR) nanomaterial that could mimic the activity of NOX by efficiently catalyzing the conversion of NADPH into NADP⁺ and triggering the generation of oxygen radicals. The resulting FeNGR nanozyme had similar cellular distribution to NOX and is able to mimic the enzyme function in NOX-deficient cells by catalyzing the generation of superoxide and retrieving the immune activity, evidenced by TNF-α, IL-1β, and IL-6 production in response to Alum exposure. Overall, our study discovered a synthetic material (FeNGR) to mimic NOX and demonstrated its biological function in immune activation of NOX-deficient cells.