Activity Of Nanozymes Research Articles

Multimodal lab-on-a-tube detection of AFB1 based on fluorescence and nanozyme activity of DNA templated silver nanocluster: Enhanced sensitivity through G-quadruplex formation

Aflatoxin B1 (AFB1) is the potent carcinogenic toxin secreted by fungi with widespread distribution around the world as the food contaminant. In the present study, a novel strategy has been developed for sensitive detection of AFB1 based on multiplex aptamer mediated probe and ExoIII enzyme activity. Inspired by generated fluorescence signal by DNA templated silver nanocluster (AgNCs), a specific aptasensor was designed to provide efficient interaction with AFB1 and subsequent amplify the released heterostructure included G-quadruplex after Exo-assisted activity for AgNCs fabrication. This strategy triggered repeated recognition-sensing cycle, leading to output colorimetric and fluorometric response signal. The integration of G-quadruplex in released probe, amplified the intrinsic low quantum yield and fluorescence of synthesized AgNCs and also enhanced its nanozyme activity on TMB and H2O2 substrate for colorimetric detection in single tube reaction. The developed AFB1 sensing assay showed LOD of 2.5 pM in colorimetric mode and had more sensitive LOD of 8.5 fM in fluorescence analysis. Smartphone assisted assay was also applied successfully as competitive detection approach. The proposed strategy was applicable in real sample and showed reliable results. Overall, this platform takes advantages of sensitive fluorometric analysis and nanozyme assisted colorimetric method which make it promising in practical application.

Continuous input DNA Nanomachine to program automated tumor diagnosis and treatment system

The diagnosis of a single disease marker can provide important information about the occurrence and progression of the disease, but a single marker may not be sufficient to identify a certain type of disease and lead to false-positive results. Molecular logic gates provide smart options for simultaneous detection of biomarkers. In order to diagnose early-stage cancer with high sensitivity and directly perform automated precision treatment on identified cancer cells. In this study, all identification and computation modules were integrated into a single structure to construct a Pd@Pt ONPs-DNA nanomachine logic gate nanodevice, which enables specific recognition of three overexpressed cancer cell biomarkers. When any of the biomarkers are overexpressed, the OR logic circuit outputs a fluorescent signal, indicating the occurrence of a positive event. At the same time, the resulting fluorescence signal is then fed directly into the AND logic gate, when the input is (1, 1, 1), a laser output of 808 nm is generated. The photothermal properties and nanozyme activity of Pd@Pt ONPs convert the 808 nm laser into cytotoxicity, using continuously connected OR and AND gates for early warning of cancer and automatic and precise treatment.

Nanozymes for biomedical applications: Multi-metallic systems may improve activity but at the cost of higher toxicity?

Nanozymes are nanomaterials with intrinsic enzyme-like activity with selected advantages over native enzymes such as simple synthesis, controllable activity, high stability, and low cost. These materials have been explored as surrogates to natural enzymes in biosensing, therapeutics, environmental protection, and many other fields. Among different nanozymes classes, metal- and metal oxide-based nanozymes are the most widely studied. In recent years, bi- and tri-metallic nanomaterials have emerged often showing improved nanozyme activity, some of which even possess multifunctional enzyme-like activity. Taking this concept even further, high-entropy nanomaterials, that is, complex multicomponent alloys and ceramics like oxides, may potentially enhance activity even further. However, the addition of various elements to increase catalytic activity may come at the cost of increased toxicity. Since many nanozyme compositions are currently being explored for in vivo biomedical applications, such as cancer therapeutics, toxicity considerations in relation to nanozyme application in biomedicine are of vital importance for translation. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Diagnostic Tools > Diagnostic Nanodevices.

Laser-assembled conductive 3D nanozyme film-based nitrocellulose sensor for real-time detection of H2O2 released from cancer cells

In this work, a nanostructured conductive film possessing nanozyme features was straightforwardly produced via laser-assembling and integrated into complete nitrocellulose sensors; the cellulosic substrate allows to host live cells, while the nanostructured film nanozyme activity ensures the enzyme-free real-time detection of hydrogen peroxide (H2O2) released by the sames. In detail, a highly exfoliated reduced graphene oxide 3D film decorated with naked platinum nanocubes was produced using a CO2-laser plotter via the simultaneous reduction and patterning of graphene oxide and platinum cations; the nanostructured film was integrated into a nitrocellulose substrate and the complete sensor was manufactured using an affordable semi-automatic printing approach. The linear range for the direct H2O2 determination was 0.5–80 μM (R2 = 0.9943), with a limit of detection of 0.2 μM. Live cell measurements were achieved by placing the sensor in the culture medium, ensuring their adhesion on the sensors' surface; two cell lines were used as non-tumorigenic (Vero cells) and tumorigenic (SKBR3 cells) models, respectively. Real-time detection of H2O2 released by cells upon stimulation with phorbol ester was carried out; the nitrocellulose sensor returned on-site and real-time quantitative information on the H2O2 released proving useful sensitivity and selectivity, allowing to distinguish tumorigenic cells. The proposed strategy allows low-cost in-series semi-automatic production of paper-based point-of-care devices using simple benchtop instrumentation, paving the way for the easy and affordable monitoring of the cytopathology state of cancer cells.

A high oxidase-like activity, bimetallic single-atom nanozyme FeCe/NC prepared by FeCe-ZIF-8 approach for sensing tannic acid in tea

To improve the activity of single-atom nanozymes (SAzymes) for applications in food analysis, a new bimetal SAzyme FeCe/NC was developed. Its oxidase-like activity is 40% higher than that of single metal SAzyme Fe/NC. Based on a series of characterization investigations, the catalytic mechanism is that it directly catalyzed O2 to generate •OH, O2•-and 1O2. It could directly catalyze oxidation 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxTMB, thereunder, a FeCe/NC SAzyme-TMB colorimetric method for the detection of tannic acid (TA) was constructed after the optimization of catalytic conditions. The method has a high R2 of 0.995, a low limit of detection (LOD) of 0.26 μmol/L, and high stability. The detection performance was validated by the real samples (tea). Therefore, the prepared bimetallic SAzyme FeCe/NC can be applied for TA detection without the addition of H2O2, and will have broad applications in the areas of food, feed, and life science.

Montmorillonite‐supported Ru‐doped CuBi2O4 nanozyme with enhanced peroxidase‐like activity for sensitive determination of hydroquinone

Nanozymes constitute a category of nanomaterials presenting the potential to replace natural enzymes. Nonetheless, weak catalytic activity becomes the biggest barrier hindering their practical applications. In this study, we fabricated a montmorillonite (MMT)‐supported ruthenium (Ru)‐doped CuBi2O4 nanozyme (Ru/CuBi2O4‐MMT) with robust peroxidase (POD)‐like activity by hydrothermal method and studied its application in determination of hydroquinone (HQ). Specifically, the CuBi2O4 material is brought into nanozyme field for the first time. MMT‐supported CuBi2O4 material possesses smaller size and larger surface area than pure CuBi2O4. Ru‐doped exhibits significantly higher POD‐like activity in comparison to CuBi2O4 due to the increase of defect sites. Both of strategies synergistically enhance the POD‐like activity of CuBi2O4 material. The POD‐like activity of nanozyme originates from the photogenerated holes (h+) and superoxide radicals (•O2−) produced during the catalytic decomposition of H2O2. Ru/CuBi2O4‐MMT nanozyme can be successfully applied for HQ colorimetric detection by redox reaction. Our newly developed nanozyme exhibits exceptional POD‐like activity by introducing support and element doping strategies, holding great potential for detecting pollutants in practical applications.

Photoaged nanoplastics with multienzyme-like activities significantly shape the horizontal transfer of antibiotic resistance genes

Nanoplastics (NPs), identified as emerging pollutants, pose a great risk to environment and global public health, exerting profound influences on the prevalence and dissemination of antibiotic resistance genes (ARGs). Despite evidence suggesting that nano-sized plastic particles can facilitate the horizontal gene transfer (HGT) of ARGs, it is imperative to explore strategies for inhibiting the transfer of ARGs. Currently, limited information exists regarding the characteristics of environmentally aged NPs and their impact on ARGs propagation. Herein, we investigated the impact of photo-aged NPs on the transfer of ARG-carrying plasmids into Escherichia coli (E. coli) cells. Following simulated sunlight irradiation, photo-aged nano-sized polystyrene plastics (PS NPs) exhibited multiple enzyme-like activities, including peroxidase (POD) and oxidase (OXD), leading to a burst of reactive oxygen species (ROS). At relatively low concentrations (0.1, 1 μg/mL), both pristine and aged PS NPs facilitated the transfer of pUC19 and pHSG396 plasmids within E. coli due to moderate ROS production and enhanced cell membrane permeability. Intriguingly, at relatively high concentrations (5, 10 μg/mL), aged PS NPs significantly suppressed plasmids transformation. The non-unidirectional impact of aged PS NPs involved the overproduction of ROS (•OH and •O2−) via nanozyme activity, directly degrading ARGs and damaging plasmid structure. Additionally, oxidative damage to bacteria resulted from the presence of much toxic free radicals, causing physical damage to cell membranes, reduction of the SOS response and restriction of adenosine-triphosphate (ATP) supply, ultimately leading to inactivation of recipient cells. This study unveils the intrinsic multienzyme-like activity of environmentally aged NPs, highlighting their potential to impede the transfer and dissemination of ARGs.

Cu,Zn,I-Doped Carbon Dots with Boosted Triple Antioxidant Nanozyme Activity for Treatment of DSS-Induced Colitis.

Nanozyme-mediated antioxidative therapy is a promising star for treating a myriad of important diseases through eliminating excessive reactive oxygen species (ROS) such as O2·- and H2O2, a critical mechanism for inflammatory bowel disease (IBD). This work provides a high biocompatibility iodine-copper-zinc covalent doped carbon dots (Cu,Zn,I-CDs) with the catalase (CAT)-, superoxide dismutase (SOD)- and glutathione peroxidase (GPx)-like catalytic activities for treating ulcerative colitis (UC) by scavenging overproduced ROS. We found that I dopant aids in counteracting the positive charge at Cu,Zn dopants brought on by low pH, enabling Cu,Zn,I-CDs to process strong triple antioxidant nanozyme activities rather than Cu,Zn-CDs. Vitro experiments displayed that the Cu,Zn,I-CDs could scavenge the excessive ROS to protect cellular against oxidative stress and reduce the expression of proinflammatory cytokines, such as TNF-α, IL-1β, and IL-6. In sodium dextran sulfate (DSS)-induced colitis mice models, Cu,Zn,I-CDs with excellent biocompatibility could effectively relieve the inflammation of the colon, containing the reduction of the colon length, the damaged epithelium, the infiltration of inflammatory cells, and upregulation of antioxidant genes. Therefore, the therapy of Cu,Zn,I-CD antioxidant nanozymes is an effective approach and provides a novel strategy for UC treatment.

Platinum Nanozyme Probes for Cellular Imaging by Electron Microscopy

The highly efficient peroxidase‐like activity of platinum nanozymes (3–20 nm size) is exploited within the complex cellular environment to catalyze the oxidation of the DAB substrate, producing an electron‐dense signal around the nanozyme surface, upon osmium staining. It is proved that such nanozyme amplification can achieve a catalytic signal enhancement up to 10‐fold, enabling the quick detection of the Pt particles (even of 3 nm size) by transmission electron microscopy (TEM) also at low magnification and across wide fields of view in the intricate intracellular milieu. The developed procedure is ideally suited to overcome standard amplification strategies currently used in TEM analysis, such as gold or silver enhancements. Furthermore, the wide versatility of the Pt‐nanozyme probes in TEM imaging is demonstrated in immuno‐EM and protein trafficking studies, showing their potential to track the subcellular localization of target biomolecules at both low and high magnifications. These results suggest that the use of nanozymes might represent a paradigm shift in the conventional amplification systems currently employed in electron microscopy for cellular analyses, offering enhanced imaging capabilities.

Bimetallic Fe3O4@Co3O4/CN as a Nanozyme with Dual Enzyme-Mimic Activities for the Colorimetric Determination of Mercury(II)

Colorimetric biosensor-based nanozymes have received considerable attention in various fields thanks to the advantages of the simple preparation, good stability, and regulable catalytic activity of nanozymes. In this study, a bimetallic nanozyme Fe3O4@Co3O4/CN was prepared via the high-temperature calcination of Fe3O4-PVP@ZIF-67. The material retained its skeletal structure before calcination, which prevented the aggregation of nanoparticles and exposed more active sites of the nanozyme, substantially enhancing the intrinsic dual enzyme-mimetic activities, including peroxidase- and oxidase-like activities. In particular, Fe3O4@Co3O4/CN with oxidase-like activity catalyzed the colorless tetramethylbenzidine (TMB) to become blue oxTMB with oxygen. Reducing glutathione (GSH) could inhibit the above oxidation reaction. In contrast, with respect to the existence of mercury(II), GSH bound to mercury(II) due to the strong affinity between mercury(II) and -SH, thus eliminating the inhibition and restoring the oxTMB signal. A simple and effective colorimetric sensor was fabricated to detect mercury(II) based on the above principles. The proposed measurement had a linear range of 0.1–15 μM and a limit of detection (LOD) of 0.017 μM. It was shown that the established colorimetric sensing system could be successfully applied to detect mercury(II) in water samples, and the Fe3O4@Co3O4/CN nanozyme proved to be a promising candidate for biosensing application.

Deciphering the Catalytic Mechanism of Peroxidase-like Activity of Iron Sulfide Nanozymes.

Iron sulfide nanomaterials represented by FeS2 and Fe3S4 nanozymes have attracted increasing attention due to their biocompatibility and peroxidase-like (POD-like) catalytic activity in disease diagnosis and treatments. However, the mechanism responsible for their POD-like activities remains unclear. Herein, taking the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 on FeS2(100) and Fe3S4(001) surfaces, the catalytic mechanism was investigated in detail using density functional theory (DFT) calculations and experimental characterizations. Our experimental results showed that the catalytic activity of FeS2 nanozymes was significantly higher than that of Fe3S4 nanozymes. Our DFT calculations indicated that the surface iron ions of iron sulfide nanozymes could effectively catalyze the production of HO• radicals via the interactions between Fe 3d electrons and the frontier orbitals of H2O2 in the range of -10 to 5 eV. However, FeS2 nanozymes exhibited higher POD-like activity due to the surface Fe(II) binding to H2O2, forming inner-orbital complexes, which results in a larger binding energy and a smaller energy barrier for the base-like decomposition of H2O2. In contrast, the surface iron ions of Fe3S4 nanozymes bind to H2O2, forming outer-orbital complexes, which results in a smaller binding energy and a larger energy barrier for the base-like decomposition of H2O2. The charge transfer analysis showed that FeS2 nanozymes transferred 0.12 e and Fe3S4 nanozymes transferred 0.05 e from their surface iron ions to H2O2, respectively. The simulations were consistent with the experimental observations that the FeS2 nanozymes had a greater affinity for H2O2 compared to that of Fe3S4 nanozymes. This work provides a theoretical foundation for the rational design and accurate preparation of iron sulfide functional nanozymes.

Superior oxidase-mimetic activity of FeCo-NC dual-atom nanozyme for smartphone-based visually colorimetric assay of organophosphorus pesticides.

A colorimetric analysis platformhas been successfully developedbased on FeCo-NC dual-atom nanozyme (FeCo-NC DAzyme) for the detection of organophosphorus pesticides (OPPs). The FeCo-NC DAzyme exhibited exceptional oxidase-like activity (OXD), enabling the catalysis of colorless TMB to form blue oxidized TMB (oxTMB) without the need for H2O2 involvement. By combining acid phosphatase (ACP) hydrolase with FeCo-NC DAzyme, a "FeCo-NC DAzyme + TMB + ACP + SAP" colorimetric system was constructed, which facilitated the rapid detection of malathion. Thechromogenic system was appliedto detect malathion using a smartphone-based app and an auxiliary imaging interferogram device for colorimetric measurements, which have a linear range of 0.05-4.0 µM and a limit of detection (LOD) as low as 15 nM in real samples, comparable to UV-Vis and HPLC-DAD detection methods. Overall, these findings present a novel approach for convenient, rapid, and on-site monitoring of OPPs.

Construction of phosphatase-like COF-OMe@Valine-CeO2 nanozymes for ultrasensitive electrochemical detection of organophosphorus pesticides

Construction of highly-active artificial nanozymes for pesticides detection has great significance of human health and ecological systems. Herein, we have successfully designed a two-step approach to synthesize the TAPB-DMTP-COF (hereafter denoted as COF-OMe, TAPB, 1,3,5-tris(4-aminophenyl)benzene; DMTP, 2,5-dimethoxyterephaldehyde; COF, covalent organic framework)@Valine integrated cerium oxide nanozymes (COF-OMe@Valine-CeO2) with phosphatase-like activities, which can cleave phosphate bonds (PO) of organophosphorus pesticides (OPs) for the formation of electroactive p-nitrophenol (p-NP). In detail, the Ce (IV)/Ce (III) species serve as the active sites to polarize and hydrolyze PO bond in OPs, and the excellent adsorption performance of porous COF-OMe toward OPs could promote the hydrolysis process of PO. Moreover, the efficient charge transfer at the covalent interface of COF-OMe@Valine-CeO2 also contributed to this excellent catalytic process. By virtue of those advantages, the COF-OMe@Valine-CeO2 electrochemical platform was successfully applied in methyl-paraoxon (MP) detection. The resulting electrochemical sensors displayed high sensitivity, a wide linear response range of 0.034–76 μmol/L, and low detection limits of 0.011 μmol/L for MP. The research not only provides a preparation method for COF with excellent nanozyme activity, but broadens some new insights for the design of highly efficient nanozymes for on-time detection for OPs.

ChatGPT Combining Machine Learning for the Prediction of Nanozyme Catalytic Types and Activities.

The design of nanozymes with superior catalytic activities is a prerequisite for broadening their biomedical applications. Previous studies have exerted significant effort in theoretical calculation and experimental trials for enhancing the catalytic activity of nanozyme. Machine learning (ML) provides a forward-looking aid in predicting nanozyme catalytic activity. However, this requires a significant amount of human effort for data collection. In addition, the prediction accuracy urgently needs to be improved. Herein, we demonstrate that ChatGPT can collaborate with humans to efficiently collect data. We establish four qualitative models (random forest (RF), decision tree (DT), adaboost random forest (adaboost-RF), and adaboost decision tree (adaboost-DT)) for predicting nanozyme catalytic types, such as peroxidase, oxidase, catalase, superoxide dismutase, and glutathione peroxidase. Furthermore, we use five quantitative models (random forest (RF), decision tree (DT), Support Vector Regression (SVR), gradient boosting regression (GBR), and fully connected deep neuron network (DNN)) to predict nanozyme catalytic activities. We find that GBR model demonstrates superior prediction performance for nanozyme catalytic activities (R2 = 0.6476 for Km and R2 = 0.95 for Kcat). Moreover, an open-access web resource, AI-ZYMES, with a ChatGPT-based nanozyme copilot is developed for predicting nanozyme catalytic types and activities and guiding the synthesis of nanozyme. The accuracy of the nanozyme copilot's responses reaches more than 90% through the retrieval augmented generation. This study provides a new potential application for ChatGPT in the field of nanozymes.

Ligand density-optimized peroxidase-like activity of gold nanoclusters for colorimetric sensing of biothiols and acetylcholinesterase

Nanozymes are emerging as an attractive alternative to natural enzymes for a wide range of biological applications, but the effect of surface ligands’ density on the catalytic activity of nanozymes remains largely unclear. Herein, taken gold nanoclusters (AuNCs) as a model nanozyme, glutathione-protected AuNCs (GSH-AuNCs) with three different ligand densities: low (l-AuNCs), medium (m-AuNCs), and high (h-AuNCs) were synthesized and the role of ligand density on the catalytic activity of GSH-AuNCs was systematically investigated. It was disclosed that a relatively lower ligand density is favorable for the peroxidase-like catalytic activity due to weaker steric hindrance effects. Consequently, colorimetric detection of biothiols (e.g., cysteine) and acetylcholinesterase activity was successfully achieved based on the peroxidase property of ligand density-optimized AuNCs, which exhibit a detection limit of 0.08 μM and 0.005 mU/mL, respectively. Moreover, application of the present system for detection of acetylcholinesterase activity in human serum samples was successfully demonstrated. This study provides new avenues for designing robust nanozymes with enhanced catalytic performances for application in biocatalysis as well as biosensing.

Engineering nickel-supported osmium bimetallic nanozymes with specifically improved peroxidase-like activity for immunoassay

Researchers have shown significant interest in modulating the peroxidase-like activity of nanozymes. Among these, bimetallic nanozymes have shown superior peroxidase-like activity over monometallic counterparts, offering enhanced performance and cost-efficiency in nanozyme designs. Herein, bimetallic nanozymes comprising nickel (Ni) and osmium (Os) incorporated into hyaluronate (HA) have been developed, resulting in HA-Nin/Os nanoclusters. Subsequently, comprehensive characterizations have been conducted. Further investigation has revealed that HA-Nin/Os efficiently catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation with hydrogen peroxide (H2O2), confirming its peroxidase-like behavior and role as a nanozyme. Impressively, HA-Ni2/Os (Ni/Os = 2:1) displays heightened substrate affinity, accelerated reaction rates, enhanced hydroxyl radical production in acidic conditions, and exhibits activity unit of 1224 U/mg, representing more than two-fold increase compared to non-Ni-supported Os nanozyme. Theoretical calculations indicate that Ni support enhances the peroxidase-like process of Os nanozyme by improving H2O2 adsorption and TMB oxidation. Crucially, the support of Ni does not significantly alter the other enzyme-like activities of Os nanozymes, thereby enabling Ni to selectively enhance their peroxidase-like activity. In terms of application, the peroxidase-like ability of HA-Ni2/Os, facilitated by HA's carboxyl groups enabling crosslinking, proves effective in a squamous carcinoma antigen immunoassay. Moreover, HA-Ni2/Os exhibit reliable stability, promising as a peroxidase substitute. This work underscores the advantages of incorporating Ni into Os, specifically enhancing peroxidase-like activity, highlighting the potential of Os bimetallic nanozymes for peroxidase-based applications.

Colorimetric/fluorescent dual-mode assay for antioxidant capacity of gallnuts based on CuCo nanozyme and AIE luminogen

In this work, we present a dual-mode assay system consisting of a nanozyme and a luminogen with the aggregation-induced emission (AIE) feature. In the assay system, the chosen nanozyme named CuCo-0 catalyzes the substrate to produce colorimetric signals, while the aggregates of H4ETTC (4,4′,4″,4‴-(ethene-1,1,2,2-tetrayl) tetrakis ([1,1′-biphenyl]-4-carboxylic acid), a typical AIE luminogen, generate fluorescent signals. The peroxidase-like activity of the CuCo-0 nanozyme can be remarkably suppressed with sequential additions of antioxidants, leading to a dual-signal response characterized by enhanced fluorescence emission and reduced UV-vis absorbance. On this basis, a dual-mode assay capable of producing both colorimetric and fluorescent signals for the assessment of antioxidant capacity using gallic acid as a representative antioxidant was exploited. Good linearity can be obtained in the 0–60 μM range for both colorimetric analysis and fluorescent analysis, with detection limits of 1.3 μM and 0.35 μM, respectively. Furthermore, this dual-mode assay was successfully applied to real gallnut samples, yielding satisfactory results.

Detection of Cr(III) and Cr(VI) in lake water by inhibiting and enhancing oxidase-like activity of iron-manganese bimetallic oxide nano-cubes

In recent years, most of the researches on nanozymes have focused on improving their catalytic activity and direct synthesis, but this task is still very complicated. Bimetallic oxides are particularly popular because of their mixed valence and special structure. In this study, iron-manganese bimetallic oxide nano-cubes (IMBO NCs) were prepared by a rapid and effective solvothermal synthesis technique, and showed excellent oxidase-like activity. The exposure of Cr(III) and Cr(VI) inhibited and enhanced the catalytic activity of IMBO NCs respectively. On this basis, a simple, economical and accurate colorimetric sensor was established by combining with 3,3′,5,5′-tetramethylbenzidine (TMB). Using oxidase activity instead of traditional peroxidase activity to detect Cr(III) and Cr(VI) greatly shortens the detection time. The method has also been successfully applied to the quantitative monitoring of Cr(III) and Cr(VI) in lake water. This study provides theoretical support for the effective design of bimetallic oxide nanozyme activity and can guide the development of accurate detection systems for the analysis of Cr(III) in food and Cr(VI) in environment.

Optimization of metal–organic framework nanozyme activity via histidine modification for simultaneous pesticide detection

Biosensors provide simple, rapid and sensitive detection of a wide range of analytes. Recently, they have been widely used for the rapid detection of pesticides, which makes up for the shortcomings of traditional detection methods. However, the catalytic activity of some nanozymes is not satisfactory in practical applications, limiting the performance of biosensors. Further development of highly active and stable nanozymes is conducive to improving the sensitivity of the sensors and expanding their application in practical detection. Herein we simulated the amino acid microenvironment of natural enzymes and synthesized His-MIL-101(Fe)-X with different histidine (His) modification amounts (X = 0, 25%, 50%, 75%) by regulating the ratio of histidine and terephthalic acid ligands using a one-step solvothermal method. With increasing histidine doping, the peroxidase-like activity of His-MIL-101(Fe)-X was gradually enhanced, and the sensing performance of the sensor arrays constructed by combining His-MIL-101(Fe)-X with three peroxidase substrates was also gradually improved, with a 25-fold increase in detection limit. The His-MIL-101(Fe)-75% sensor array was not only able to accurately discriminate five pesticides in the range of 2-100 μM, but also to quantitatively identify different concentrations of pesticides. Moreover, the His-MIL-101(Fe)-75% sensor array showed good anti-interference capability and was able to discriminate five pesticides at only 2 μM in soil, lake water, seawater, and apple samples, as well as quantitatively detecting diafenthiuron, which has great potential for practical application.

Catalytic Nanoparticles in Biomedical Applications: Exploiting Advanced Nanozymes for Therapeutics and Diagnostics.

Catalytic nanoparticles (CNPs) as heterogeneous catalyst reveals superior activity due to their physio-chemical features, such as high surface-to-volume ratio and unique optical, electric, and magnetic properties. The CNPs, based on their physio-chemical nature, can either increase the reactive oxygen species (ROS) level for tumor and antibacterial therapy or eliminate the ROS for cytoprotection, anti-inflammation, and anti-aging. In addition, the catalytic activity of nanozymes can specifically trigger a specific reaction accompanied by the optical feature change, presenting the feasibility of biosensor and bioimaging applications. Undoubtedly, CNPs play a pivotal role in pushing the evolution of technologies in medical and clinical fields, and advanced strategies and nanomaterials rely on the input of chemical experts to develop. Herein, a systematic and comprehensive review of the challenges and recent development of CNPs for biomedical applications is presented from the viewpoint of advanced nanomaterial with unique catalytic activity and additional functions. Furthermore, the biosafety issue of applying biodegradable and non-biodegradable nanozymes and future perspectives are critically discussed to guide a promising direction in developing span-new nanozymes and more intelligent strategies for overcoming the current clinical limitations.