Nanoparticles containing magnetic materials, such as magnetite (Fe3O4), are particularly useful for imaging and separation techniques. As these nanoparticles are generally considered to be biologically and chemically inert, they are typically coated with metal catalysts, antibodies or enzymes to increase their functionality as separation agents. Here, we report that magnetite nanoparticles in fact possess an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, which are widely used to oxidize organic substrates in the treatment of wastewater or as detection tools. Based on this finding, we have developed a novel immunoassay in which antibody-modified magnetite nanoparticles provide three functions: capture, separation and detection. The stability, ease of production and versatility of these nanoparticles makes them a powerful tool for a wide range of potential applications in medicine, biotechnology and environmental chemistry.

As pioneering Fe3O4 nanozymes, their explicit peroxidase (POD)-like catalytic mechanism remains elusive. Although many studies have proposed surface Fe2+-induced Fenton-like reactions accounting for their POD-like activity, few have focused on the internal atomic changes and their contribution to the catalytic reaction. Here we report that Fe2+ within Fe3O4 can transfer electrons to the surface via the Fe2+-O-Fe3+ chain, regenerating the surface Fe2+ and enabling a sustained POD-like catalytic reaction. This process usually occurs with the outward migration of excess oxidized Fe3+ from the lattice, which is a rate-limiting step. After prolonged catalysis, Fe3O4 nanozymes suffer the phase transformation to γ-Fe2O3 with depletable POD-like activity. This self-depleting characteristic of nanozymes with internal atoms involved in electron transfer and ion migration is well validated on lithium iron phosphate nanoparticles. We reveal a neglected issue concerning the necessity of considering both surface and internal atoms when designing, modulating, and applying nanozymes.

Nanomaterials with enzyme-like properties has attracted significant interest, although limited information is available on their biological activities in cells. Here we show that V2O5 nanowires (Vn) functionally mimic the antioxidant enzyme glutathione peroxidase by using cellular glutathione. Although bulk V2O5 is known to be toxic to the cells, the property is altered when converted into a nanomaterial form. The Vn nanozymes readily internalize into mammalian cells of multiple origin (kidney, neuronal, prostate, cervical) and exhibit robust enzyme-like activity by scavenging the reactive oxygen species when challenged against intrinsic and extrinsic oxidative stress. The Vn nanozymes fully restore the redox balance without perturbing the cellular antioxidant defense, thus providing an important cytoprotection for biomolecules against harmful oxidative damage. Based on our findings, we envision that biocompatible Vn nanowires can provide future therapeutic potential to prevent ageing, cardiac disorders and several neurological conditions, including Parkinson's and Alzheimer's disease.

Neurotrauma is one of the most serious traumatic injuries, which can induce an excess amount of reactive oxygen and nitrogen species (RONS) around the wound, triggering a series of biochemical responses and neuroinflammation. Traditional antioxidant-based bandages can effectively decrease infection preventing oxidative stress, but its effectiveness is limited to a short period of time due to the rapid loss of electron-donating ability. Herein, we developed a nanozyme-based bandage using single-atom Pt/CeO with a persistent catalytic activity for noninvasive treatment of neurotrauma. Single-atom Pt induced the lattice expansion and preferred distribution on (111) facets of CeO, enormously increasing the endogenous catalytic activity. Pt/CeO showed a 2-10 times higher scavenging activity against RONS as well as 3-10 times higher multienzyme activities compared to CeO clusters. The single-atom Pt/CeO retained the long-lasting catalytic activity for up to a month without obvious decay due to enhanced electron donation through the Mars-van Krevelen reaction. studies disclosed that the nanozyme-based bandage at the single-atom level can significantly improve the wound healing of neurotrauma and reduce neuroinflammation.

Water-soluble cupric oxide nanoparticles are fabricated via a quick-precipitation method and used as peroxidase mimetics for ultrasensitive detection of hydrogen peroxide and glucose. The water-soluble CuO nanoparticles show much higher catalytic activity than that of commercial CuO nanoparticles due to their higher affinity to hydrogen peroxide. In addition, the as-prepared CuO nanoparticles are stable over a wide range of pH and temperature. This excellent stability in the form of aqueous colloidal suspensions makes the application of the water-soluble CuO nanoparticles easier in aqueous systems. A colorimetric assay for hydrogen peroxide and glucose has been established based on the catalytic oxidation of phenol coupled with 4-amino-atipyrine by the action of hydrogen peroxide. This analytical platform not only confirms the intrinsic peroxidase-like activity of the water-soluble cupric oxide nanoparticles, but also shows its great potential applications in environmental chemistry, biotechnology and medicine.

A chemiluminescent cholesterol sensor with good selectivity and enhanced sensitivity was constructed based upon the peroxidase-like activity of cupric oxide nanoparticles. Cupric oxide nanoparticles can catalyze the oxidation of luminol by H2O2, which was produced by the reaction of cholesterol and oxygen that was catalyzed by cholesterol oxidase. Therefore, the oxidation of cholesterol could be transduced into the chemiluminescence of luminol by combining these two reactions. Under the optimum conditions, the CL intensity was proportional to the concentration of cholesterol over the range of 0.625-12.5μM and a detection limit was 0.17μM. The applicability of proposed method has been validated by determination of cholesterol in milk powder and human serum samples with satisfactory results.Copyright © 2012 Elsevier B.V. All rights reserved.

Neurotrauma is a worldwide public health problem which can be divided into primary and secondary damge. The primary damge is caused by external forces and triggers the overproduction of peroxides and superoxides, leading to long-lasting secondary damage including oxidative stress, wound infection and immunological reactions. The emerging catalysts have shown great potential in the treatment of brain injury and neurogenic inflammation, but are limited to biosafety issues and delivery efficiency.

Noble metal-based nanomaterials have shown promise as potential enzyme mimetics, but the facet effect and underlying molecular mechanisms are largely unknown. Herein, with a combined experimental and theoretical approach, we unveil that palladium (Pd) nanocrystals exhibit facet-dependent oxidase and peroxidase-like activities that endow them with excellent antibacterial properties via generation of reactive oxygen species. The antibacterial efficiency of Pd nanocrystals against Gram-positive bacteria is consistent with the extent of their enzyme-like activity, that is {100}-faceted Pd cubes with higher activities kill bacteria more effectively than {111}-faceted Pd octahedrons. Surprisingly, a reverse trend of antibacterial activity is observed against Gram-negative bacteria, with Pd octahedrons displaying stronger penetration into bacterial membranes than Pd nanocubes, thereby exerting higher antibacterial activity than the latter. Our findings provide a deeper understanding of facet-dependent enzyme-like activities and might advance the development of noble metal-based nanomaterials with both enhanced and targeted antibacterial activities.

Metal nanozyme has attracted wide interest for biomedicine, and a highly catalytic material in the physiological environment is highly desired. However, catalytic selectivity of nanozyme is still highly challenging, limiting its wide application. Here, we show a trimetallic (triM) nanozyme with highly catalytic activity and environmental selectivity. Enzyme-mimicked investigations find that the triM system possesses multi-enzyme-mimetic activity for removing reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as O, HO, OH, and NO. Importantly, triM nanozyme exhibits the significant neutral environment preference for removing the OH, O, and NO free radical, indicating its highly catalytic selectivity. The density functional theory (DFT) calculations reveal that triM nanozyme can capture electrons very easily and provides more attraction to reactive oxygen and nitrogen species (RONS) radicals in the neutral environment. In vitro experiments show that triM nanozyme can improve the viability of injured neural cell. In the LPS-induced brain injury model, the superoxide dismutase (SOD) activity and lipid peroxidation can be greatly recovered after triM nanozyme treatment. Moreover, the triM nanozyme treatment can significantly improve the survival rate, neuroinflammation, and reference memory of injured mice. Present work provides a feasible route for improving selectivity of nanozyme in the physiological environment as well as exploring potential applications in brain science.

Zhao, Meiting; Wang, Yixian; Ma, Qinglang; Huang, Ying; Zhang, Xiao; Ping, Jianfeng; Zhang, Zhicheng; Lu, Qipeng; Yu, Yifu; Xu, Huan; Zhang, Hua Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore. Wang, Yixian; Ping, Jianfeng Zhejiang Univ, Sch Biosyst Engn & Food Sci, Hangzhou 310058, Zhejiang, Peoples R China. Ma, Qinglang Nanyang Technol Univ, Interdisciplinary Grad Sch, Nanyang Environm & Water Res Inst, Singapore 639798, Singapore. Zhao, Yanli Nanyang Technol Univ, Sch Phys & Math Sci, Div Chem & Biol Chem, Singapore 637371, Singapore.

Over the past few decades, researchers have established artificial enzymes as highly stable and low-cost alternatives to natural enzymes in a wide range of applications. A variety of materials including cyclodextrins, metal complexes, porphyrins, polymers, dendrimers and biomolecules have been extensively explored to mimic the structures and functions of naturally occurring enzymes. Recently, some nanomaterials have been found to exhibit unexpected enzyme-like activities, and great advances have been made in this area due to the tremendous progress in nano-research and the unique characteristics of nanomaterials. To highlight the progress in the field of nanomaterial-based artificial enzymes (nanozymes), this review discusses various nanomaterials that have been explored to mimic different kinds of enzymes. We cover their kinetics, mechanisms and applications in numerous fields, from biosensing and immunoassays, to stem cell growth and pollutant removal. We also summarize several approaches to tune the activities of nanozymes. Finally, we make comparisons between nanozymes and other catalytic materials (other artificial enzymes, natural enzymes, organic catalysts and nanomaterial-based catalysts) and address the current challenges and future directions (302 references).

CuS nanoparticles (NPs) was synthesized through a simple and green method using water soluble precursor complex [CuL2(H2O)2]Cl2 (L=pyridine 2-carboxamide) and was characterized by X-ray diffraction analysis (XRD), transmission electron microscopy (TEM) and UV-Vis spectroscopic techniques. The as-prepared CuS NPs (covellite) was demonstrated to possess intrinsic peroxidase-like activity using 3,3',5,5'-tetramethylbenzidine (TMB), as a peroxidase substrate, in presence of H2O2 which show good affinity towards both TMB and H2O2. Using this TMB-H2O2 catalyzed color reaction; the CuS NPs was exploited as a new type of biosensor for detection and estimation of glucose through a simple, cheap and selective colorimetric method in a linear range from 2 to 1800 μM with a detection limit of 0.12 μM. On the basis of the developed reaction process, we can easily monitor human blood glucose level.Copyright © 2013 Elsevier B.V. All rights reserved.

Metal-organic frameworks (MOFs) with tunable structures and properties have recently been emerged as very interesting functional materials. However, the catalytic properties of MOFs as enzymatic mimics remain to be further investigated. In this work, we for the first time demonstrated the peroxidase-like activity of copper-based MOFs (HKUST-1) by employing thiamine (TH) as a peroxidase substrate. In the presence of H2O2, HKUST-1 can catalyze efficiently the conversion of non-fluorescent TH to strong fluorescent thiochrome. The catalytic activity of HKUST-1 is highly dependent on the temperature, pH and H2O2 concentrations. As a peroxidase mimic, HKUST-1 not only has the features of low cost, high stability and easy preparation, but also follows Michaelis-Menten behaviors and shows stronger affinity to TH than horseradish peroxidase (HRP). Based on the peroxidase-like activity of HKUST-1, a simple and sensitive fluorescent method for TH detection has been developed. As low as 1 μM TH can be detected with a linear range from 4 to 700 μM. The detection limit for TH is about 50 fold lower than that of HRP-based fluorescent assay. The proposed method was successfully applied to detect TH in tablets and urine samples and showed a satisfactory result. We believed that the present work could improve the understanding of catalytic behaviors of MOFs as enzymatic mimics and find out a wider application in bioanalysis.Copyright © 2014 Elsevier B.V. All rights reserved.

Reactive oxygen species (ROS) as a key messenger of signal transduction mediate physiological activities, however, oxidative stress produced by excessive ROS can cause the destruction of cell homeostasis, which will result in a series of diseases. Therefore, effective control of ROS level is critical to the homeostasis of the cell. Here, we reported that glutathione (GSH)-stabilized copper nanoclusters (CuNCs) with about 9 Cu atoms can functionally mimic three major antioxidant enzymes, namely catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD). The rate of HO decomposition was calculated to be ∼0.23 mg L s when the concentration of CuNCs was 100 μg mL. The SOD-like activity by catalyzing the disproportionation of superoxide to HO and O reached 25.6 U mg when the effective inhibition rate was ∼55.4%. Intracellular ROS scavenging studies further identified that CuNCs can obviously protect cells from oxidative stress and the cell viability recovered to above 90%. Hence, we expect that ultrasmall CuNCs will provide good therapeutic potential in the future treatment of ROS-related diseases.This journal is © The Royal Society of Chemistry.

Atomically mimicking the enzyme-like active sites based on nanomaterials would develop unexpected single-atom nanozymes.

Electrospray ionization mass spectrometry (ESI-MS) is an analytical technique that measures the mass of a sample through "soft" ionization. Recent years have witnessed a rapid growth of its application in noble-metal nanocluster (NC) analysis. ESI-MS is able to provide the mass of a noble-metal NC analyte for the analysis of their composition (n, m, q values in a general formula [M L ] ), which is crucial in understanding their properties. This review attempts to present various developed techniques for the determination of the composition of noble metal NCs by ESI-MS. Additionally, advanced applications that use ESI-MS to further understand the reaction mechanism, complexation behavior, and structure of noble metal NCs are introduced. From the comprehensive applications of ESI-MS on noble-metal NCs, more possibilities in nanochemistry can be opened up by this powerful technique.© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Emerging artificial enzymes with reprogrammed and augmented catalytic activity and substrate selectivity have long been pursued with sustained efforts. The majority of current candidates have rather poor catalytic activity compared with natural molecules. To tackle this limitation, we design artificial enzymes based on a structurally well-defined Au25 cluster, namely clusterzymes, which are endowed with intrinsic high catalytic activity and selectivity driven by single-atom substitutions with modulated bond lengths. Au24Cu1 and Au24Cd1 clusterzymes exhibit 137 and 160 times higher antioxidant capacities than natural trolox, respectively. Meanwhile, the clusterzymes demonstrate preferential enzyme-mimicking catalytic activities, with Au25, Au24Cu1 and Au24Cd1 displaying compelling selectivity in glutathione peroxidase-like (GPx-like), catalase-like (CAT-like) and superoxide dismutase-like (SOD-like) activities, respectively. Au24Cu1 decreases peroxide in injured brain via catalytic reactions, while Au24Cd1 preferentially uses superoxide and nitrogenous signal molecules as substrates, and significantly decreases inflammation factors, indicative of an important role in mitigating neuroinflammation.

Current cancer therapy is seriously challenged by tumor metastasis and recurrence. One promising solution to these problems is to build antitumor immunity. However, immunotherapeutic efficacy is highly impeded by the immunosuppressive state of the tumors. Here a new strategy is presented, catalytic immunotherapy based on artificial enzymes. Cu Te nanoparticles exhibit tunable enzyme-mimicking activity (including glutathione oxidase and peroxidase) under near-infrared-II (NIR-II) light. The cascade reactions catalyzed by the Cu Te artificial enzyme gradually elevates intratumor oxidative stress to induce immunogenic cell death. Meanwhile, the continuously generated oxidative stress by the Cu Te artificial enzyme reverses the immunosuppressive tumor microenvironment, and boosts antitumor immune responses to eradicate both primary and distant metastatic tumors. Moreover, immunological memory effect is successfully acquired after treatment with the Cu Te artificial enzyme to suppress tumor relapse.© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal-organic frameworks (MOFs) have sparked increasing interest in mimicking the structure and function of natural enzymes. However, their catalytic and therapeutic efficiency are unsatisfactory due to the relatively lower catalytic activity. Herein, inspired by nature, a MOF@COF nanozyme has been designed as a high-efficiency peroxidase mimic, with the metallic nodes of MOFs as active centres, the hierarchical nanocavities produced by the growth of covalent organic frameworks (COFs) as binding pockets to form tailored pore microenvironment around active sites for enriching and activating substrate molecules, to perform enhanced bacterial inhibition. Furthermore, the pseudopodia-like surface of the COFs "skin" enabled the system to catch the bacteria effectively for further amplifying the therapeutic efficiency of MOF-based nanozyme. We believe that the present study will not only facilitate the design of novel nanozymes, but also broaden the biological usage of MOF/COF-based hybrid materials.© 2020 Wiley-VCH GmbH.

Regenerable nanozymes with high catalytic stability and sustainability are promising substitutes for naturally-occurring enzymes but are limited by insufficient and non-selective catalytic activities. Herein, we developed single-atom nanozymes of RhN, VN, and Fe-Cu-N with catalytic activities surpassing natural enzymes. Notably, Rh/VN preferably forms an Rh/V-O-N active center to decrease reaction energy barriers and mediates a "two-sided oxygen-linked" reaction path, showing 4 and 5-fold higher affinities in peroxidase-like activity than the FeN and natural horseradish peroxidase. Furthermore, RhN presents a 20-fold improved affinity in the catalase-like activity compared to the natural catalase; Fe-Cu-N displays selectivity towards the superoxide dismutase-like activity; VN favors a 7-fold higher glutathione peroxidase-like activity than the natural glutathione peroxidase. Bioactive sutures with Rh/VN show recyclable catalytic features without apparent decay in 1 month and accelerate the scalp healing from brain trauma by promoting the vascular endothelial growth factor, regulating the immune cells like macrophages, and diminishing inflammation.© 2022. The Author(s).

Nanozymes have become a new generation of antibiotics with exciting broad-spectrum antibacterial properties and negligible biological toxicity. However, their inherent low catalytic activity limits their antibacterial properties. Herein, Cu single-atom sites/N doped porous carbon (Cu SASs/NPC) is successfully constructed for photothermal-catalytic antibacterial treatment by a pyrolysis-etching-adsorption-pyrolysis (PEAP) strategy. Cu SASs/NPC have stronger peroxidase-like catalytic activity, glutathione (GSH)-depleting function, and photothermal property compared with non-Cu-doped NPC, indicating that Cu doping significantly improves the catalytic performance of nanozymes. Cu SASs/NPC can effectively induce peroxidase-like activity in the presence of HO, thereby generating a large amount of hydroxyl radicals (•OH), which have a certain killing effect on bacteria and make bacteria more susceptible to temperature. The introduction of near-infrared (NIR) light can generate hyperthermia to fight bacteria, and enhance the peroxidase-like catalytic activity, thereby generating additional •OH to destroy bacteria. Interestingly, Cu SASs/NPC can act as GSH peroxidase (GSH-Px)-like nanozymes, which can deplete GSH in bacteria, thereby significantly improving the sterilization effect. PTT-catalytic synergistic antibacterial strategy produces almost 100% antibacterial efficiency against () and methicillin-resistant (). experiments show a better PTT-catalytic synergistic therapeutic performance on MRSA-infected mouse wounds. Overall, our work highlights the wide antibacterial and anti-infective bio-applications of Cu single-atom-containing catalysts.© 2021 The Authors.

The generation of reactive oxygen species (ROS) is an important mechanism of nanomaterial toxicity. We found that Prussian blue nanoparticles (PBNPs) can effectively scavenge ROS via multienzyme-like activity including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) activity. Instead of producing hydroxyl radicals (•OH) through the Fenton reaction, PBNPs were shown to be POD mimetics that can inhibit •OH generation. We theorized for the first time that the multienzyme-like activities of PBNPs were likely caused by the abundant redox potentials of their different forms, making them efficient electron transporters. To study the ROS scavenging ability of PBNPs, a series of in vitro ROS-generating models was established using chemicals, UV irradiation, oxidized low-density lipoprotein, high glucose contents, and oxygen glucose deprivation and reperfusion. To demonstrate the ROS scavenging ability of PBNPs, an in vivo inflammation model was established using lipoproteins in Institute for Cancer Research (ICR) mice. The results indicated that PBNPs hold great potential for inhibiting or relieving injury induced by ROS in these pathological processes.

Oxidative stress is associated with many acute and chronic inflammatory diseases, yet limited treatment is currently available clinically. The development of enzyme-mimicking nanomaterials (nanozymes) with good reactive oxygen species (ROS) scavenging ability and biocompatibility is a promising way for the treatment of ROS-related inflammation. Herein we report a simple and efficient one-step development of ultrasmall CuO nanoparticles (CuO USNPs) with multiple enzyme-mimicking and broad-spectrum ROS scavenging ability for the treatment of ROS-related diseases. CuO USNPs simultaneously possessing catalase-, superoxide dismutase-, and glutathione peroxidase-mimicking enzyme properties exhibit cytoprotective effects against ROS-mediated damage at extremely low dosage and significantly improve treatment outcomes in acute kidney injury, acute liver injury and wound healing. Meanwhile, the ultrasmall size of CuO USNPs enables rapid renal clearance of the nanomaterial, guaranteeing the biocompatibility. The protective effect and good biocompatibility of CuO USNPs will facilitate clinical treatment of ROS-related diseases and enable the development of next-generation nanozymes.

Nanoparticle-mediated tumor magnetic induction hyperthermia has received tremendous attention. However, it has been a challenge to improve the efficacy at 42 °C therapeutic temperatures without resistance to induced thermal stress. Therefore, we designed a magnetic hydrogel nanozyme (MHZ) utilizing inclusion complexation between PEGylated nanoparticles and α-cyclodextrin, which can enhance tumor oxidative stress levels by generating reactive oxygen species through nanozyme-catalyzed reactions based on tumor magnetic hyperthermia. MHZ can be injected and diffused into the tumor tissue due to shear thinning as well as magnetocaloric phase transition properties, and magnetic heat generated by the FeO first gives 42 °C of hyperthermia to the tumor. FeO nanozyme exerts peroxidase-like properties in the acidic environment of tumor to generate hydroxyl radicals (OH) by the Fenton reaction. The hyperthermia promotes the enzymatic activity of FeO nanozyme to produce more OH. Simultaneously, OH further damages the protective heat shock protein 70, which is highly expressed in hyperthermia to enhance the therapeutic effect of hyperthermia. This single magnetic nanoparticle exerts dual functions of hyperthermia and catalytic therapy to synergistically treat tumors, overcoming the resistance of tumor cells to induced thermal stress without causing severe side effects to normal tissues at 42 °C hyperthermia.

Metal-carbon hybrid materials have shown promise as potential enzyme mimetics for antibacterial therapy; however, the effects of metal states and corresponding antibacterial mechanisms are largely unknown. Here, two kinds of copper/carbon nanozymes were designed, with tuned copper states from Cu to Cu. Results revealed that the copper/carbon nanozymes exhibited copper state-dependent peroxidase-, catalase-, and superoxide dismutase-like activities. Furthermore, the antibacterial activities were also primarily determined by the copper state. The different antibacterial mechanisms of these two copper/carbon nanozymes were also proposed. For the CuO-modified copper/carbon nanozymes, the released Cu caused membrane damage, lipid peroxidation, and DNA degradation of Gram-negative bacteria, whereas, for Cu-modified copper/carbon nanozymes, the generation of reactive oxygen species (ROS) via peroxidase-like catalytic reactions was the determining factor against both Gram-positive and Gram-negative bacteria. Lastly, we established two bacterially infected animal models, i.e., bacteria-infected enteritis and wound healing, to confirm the antibacterial ability of the copper/carbon nanozymes. Our findings provide a deeper understanding of metal state-dependent enzyme-like and antibacterial activities and highlight a new approach for designing novel and selective antibacterial therapies based on metal-carbon nanozymes.

Point-of-care monitoring of hydrogen peroxide is important due to its wide usage in biomedicine, the household and industry. Herein, a paper sensor is developed for sensitive, visual and selective detection of H2O2 using a mesoporous metal oxide hollow sphere as a nanozyme. The mesoporous CuO hollow sphere is synthesized by direct decomposition of copper–polyphenol colloidal spheres. The obtained mesoporous CuO hollow sphere shows a large specific surface area (58.77 m2/g), pore volume (0.56 cm3/g), accessible mesopores (5.8 nm), a hollow structure and a uniform diameter (~100 nm). Furthermore, they are proven to show excellent peroxidase-like activities with Km and Vmax values of 120 mM and 1.396 × 10−5 M·s−1, respectively. Such mesoporous CuO hollow spheres are then loaded on the low-cost and disposable filter paper test strip. The obtained paper sensor can be effectively used for detection of H2O2 in the range of 2.4–150 μM. This work provides a new kind of paper sensor fabricated from a mesoporous metal oxide hollow sphere nanozyme. These sensors could be potentially used in bioanalysis, food security and environmental protection.

Single-atom nanozymes (SAzymes), as novel nanozymes with atomically dispersed active sites, are of great importance in the development of nanozymes for their high catalytic activities, the maximum utilization efficiency of metal atoms, and the simple model of active sites. Herein, the peroxidase-like SAzymes with high-concentration Cu sites on carbon nanosheets (Cu-N-C) were synthesized through a salt-template strategy. With the densely distributed active Cu atoms (∼5.1 wt %), the Cu-N-C SAzymes exhibit remarkable activity to mimic natural peroxidase. Integrating Cu-N-C SAzymes with natural acetylcholinesterase and choline oxidase, three-enzyme-based cascade reaction system was constructed for the colorimetric detection of acetylcholine and organophosphorus pesticides. This work not only provides a strategy to synthesize SAzymes with abundant active sites but also gives some new insights for robust nanozyme biosensing systems.

The healing process of infected wounds was limited by bacterial infection, excessive reactive oxygen species (ROS) accumulation, and tissue hypoxia. In order to alleviate the above situations, herein, a copper-rich multifunctional ultra-small Prussian blue nanozymes (HPP@Cu NZs) was constructed for infected wound synergistic treatment. Firstly, hyaluronic acid was modified by branched polyethyleneimine which could form a complex with copper ions, to construct copper-rich Prussian blue nanozymes. Secondly, the HPP@Cu NZs have a uniform ultra-small nano size and excellent photothermal response performance, exhibition of multifunctional enzymatic activity and anti-inflammatory properties. Finally, the slow release of copper ions in the HPP@Cu NZs could effectively promote the formation of new blood vessels, thus giving it multifunctional properties. In vitro and in vivo experiments showed that it not only could effectively inhibit and kill bacteria under 808 nm near-infrared laser but also could remove excessive ROS, regulate oxygen levels, and anti-inflammation. More importantly, the release of copper ions could synergistically promote the healing of infected wounds as well as good biocompatibility. Overall, our studies provide a multifunctional strategy for infected wounds with synergistic treatment based on carrier construction.Copyright © 2022 Elsevier B.V. All rights reserved.

Excessive production of inflammatory chemokines and reactive oxygen species (ROS) can cause a feedback cycle of inflammation response that has a negative effect on cutaneous wound healing. The use of wound-dressing materials that simultaneously absorb chemokines and scavenge ROS constitutes a novel 'weeding and uprooting' treatment strategy for inflammatory conditions. In the present study, a composite hydrogel comprising an amine-functionalized star-shaped polyethylene glycol (starPEG) and heparin for chemokine sequestration as well as CuO ultrasmall nanozymes for ROS scavenging (CuO@Hep-PEG) was developed. The material effectively adsorbs the inflammatory chemokines monocyte chemoattractant protein-1 and interleukin-8, decreasing the migratory activity of macrophages and neutrophils. Furthermore, it scavenges the ROS in wound fluids to mitigate oxidative stress, and the sustained release of CuO promotes angiogenesis. In acute wounds and impaired-healing wounds (diabetic wounds), CuO@Hep-PEG hydrogels outperform the standard-of-care product Promogram® in terms of inflammation reduction, increased epidermis regeneration, vascularization, and wound closure.© 2021 The Authors.

In this work, a tumor-targeted and multi-stimuli responsive drug delivery system has been developed for combining photoacoustic tomography imaging with chemo-phototherapy. We utilized a kind of near infrared (NIR) resonant material-hollow mesoporous copper sulfide nanoparticles (HMCuS NPs) to encapsulate doxorubicin (DOX). After that, the outer surface of HMCuS NPs was capped with multifunctional hyaluronic acid (HA) simultaneously as smart gatekeeper as well as tumor targeting moiety. Herein, HMCuS-HA could serve as a powerful contrast agent for photoacoustic tomography (PAT) to guide chemo-phototherapy by providing the identification of cancerous lesions. In vitro and in vivo studies, the nanoplatform (DOX/HMCuS-HA) pinpointed MCF-7 cells via CD44 receptor-mediated endocytosis pathway. Subsequently, intracellular enzyme-responsive controlled drug release would take place in lysosome after the HA degradation by hyaluronidase. Under near infrared (NIR) light irradiation, HMCuS NPs could not only effectively convert NIR light into heat for photothermal therapy, but also generate high levels of reactive oxygen species (ROS) for photodynamic therapy. In addition, NIR light and low pH environment could facilitate intracellular tunable drug release with spatial/temporal resolution, and thus synergistic combination of chemo-phototherapy should be simultaneously driven by an 808nm laser irradiation, which brought out an outstanding therapeutic effect. In vivo optical imaging demonstrated that HMCuS-HA significantly enhanced targeting and accumulation capacity in tumor site. Furthermore, tumor-bearing mice treated with DOX/HMCuS-HA under NIR irradiation (808nm, 2W/cm(2), 0.5min) in vivo displayed the highest inhibition ratio of about 88.9%. Taken together, our present study of the tumor-targeted and multi-stimuli responsive drug delivery system provides new insights into multimodality theranostic applications in cancer treatment.Until now, chemotherapy is still the major therapeutic approach applied in oncology. Despite their pharmacologically efficacy in cancer treatments, most chemotherapeutic agents without tumor-specific targeting ability have brought out serious toxicities to normal tissues. This study provides a promising near infrared (NIR) resonant material-hollow mesoporous copper sulfide nanoparticles (HMCuS NPs) with capping of multifunctional hyaluronic acid (HA) simultaneously as smart gatekeeper as well as tumor targeting moiety to address the above problem. After the nanoplatform (DOX/HMCuS-HA) pinpointed breast cancer cells via CD44 receptor-mediated endocytosis pathway, intracellular multi-stimuli responsive controlled drug release would take place with remarkable spatial/temporal resolution. Then photoacoustic tomography (PAT) and synergistic combination of chemo-phototherapy would be simultaneously driven by the same NIR irradiation in a coordinated way, which brought out an outstanding theranostic effect. This work can arouse broad interests among researchers in the fields of nanomedicine, nanotechnology, and drug delivery system.Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.