Mimetic Activity Research Articles

Gold nanoclusters-incorporated nanogels as hybrid nanozymes for sensitive chemiluminescence immunoassays

Nanomaterials with excellent biocompatibility hold significant potential in chemiluminescence (CL) immunoassays. However, achieving green synthesis and maintaining the structural stability of such nanomaterials remain challenging. In this study, gold nanoclusters (Au NCs) were synthesized via the reduction of bovine serum albumin (BSA). These Au NCs were electrostatically combined with horseradish peroxidase (HRP) and chemically cross-linked to form Au NCs@BSA/HRP nanogels (ABH nanogels) with enhanced structural stability. The internal honeycomb architecture of the nanogels effectively prolongs the CL reaction. Within the nanogel, the dual catalytic system, composed of the Au NCs' mimetic peroxidase activity and the enzymatic activity of HRP, demonstrated high catalytic efficiency and stability. The nanogels also enhanced the luminol-H2O2 system, producing sustained glow-type luminescence. Leveraging these properties, a sensitive and convenient CL immunoassay for CA15–3 detection was developed, with ABH nanogels serving as the signal detector. The sensor exhibited a broad linear detection range from 0.005 to 100 U/mL and a detection limit of 0.0015 U/mL (S/N = 3).

Uniform PtCoRuRhFe high-entropy alloy nanoflowers: Multi-site synergistic signal amplification for colorimetric assay of captopril.

Uniform PtCoRuRhFe high-entropy alloy nanoflowers (HEANFs) were fabricated by a simple wet-chemical co-reduction method in oleylamine for quantitative colorimetric determination of captopril (CAP) based on multi-site synergistic signal amplification. Specifically, the peroxidase mimetic activity of the PtCoRuRhFe HEANFs was examined through catalysis of 3,3',5,5'-tetramethylbenzidine (TMB) oxidation, whose catalytic mechanism was investigated by electron paramagnetic resonance (EPR) spectroscopy. The role of the ·O2- was figured out during the catalytic procedure. Further, the oxidation of TMB (oxTMB) can be effectively reduced by CAP, accompanied by quickly transforming the solution color from blue to colorless. More importantly, the absorbance at 652nm is linearly related to the CAP concentration in a range 5.0-50.0mM with a low detection limit of 2.82mM. The method has been applied to the determination of CAP in human urine samples. It offers a simple and high-efficiency method for facile and visual detection of CAP in hospitals.

A colorimetric platform using highly active Prussian blue composite nanocubes for the rapid determination of ascorbic acid and acid phosphatase.

Cobalt-doped Prussian blue composite nanocubes (Co-PB NCs) were synthesized, which can quickly convert O2 to O2•- and 1O2. Due to the presence of cobalt and iron transition metal redox electron pairs, Co-PB NCs with high oxidase mimetic activity can rapidly oxidize the substrate 3,3',5,5'-tetramethylbenzidine (TMB) to produce blue products (ox-TMB) without the assistance of unstable H2O2. Using ascorbic acid-2-phosphate trisodium salt (AAP) as a substrate, it can be converted to reduced ascorbic acid (AA) under acid phosphatase (ACP) hydrolysis, resulting in suppression of TMB oxidation. Therefore, an enzyme cascade signal amplification strategy for rapid colorimetric detection of AA/ACP was developed based on the high-efficiency oxidase-like activity of Co-PB NCs combined with the hydrolysis effect of ACP. The color changes at low concentrations of AA and ACP could be observed by the naked eye, and the detection limits of AA and ACP were 1.67μM and 0.0266 U/L, respectively. The developed colorimetric method was applied to the determination of AA in beverages and ACP in human serum, and the RSDs were less than 3%, showing good reproducibility. This work provides a promising strategy for the use of metal-doped Prussian blue composite material for the construction of rapid colorimetric sensing platforms that avoid the use of unstable hydrogen peroxide.

Sensitive detection of Vibrio parahaemolyticus via a dual-recognition colorimetric biosensor comprising Cefe-PEG-MNPs and apt-Fe@PDA

Highly accurate and sensitive detection of Vibrio parahaemolyticus is crucial for ensuring seafood safety and preventing the transmission of foodborne diseases. Herein, a dual-recognition strategy-driven colorimetric biosensor for the detection of V. parahaemolyticus was developed. This biosensor was based on the use of PEG-mediated cefepime-functionalized magnetic nanoparticles (Cefe-PEG-MNPs) and aptamer-modified Fe-doped polydopamine (Fe@PDA) nanozymes. The magnetic platform Cefe-PEG-MNPs was introduced to enhance the enrichment efficiency of V. parahaemolyticus, achieving a capture efficiency exceeding 90%. The Fe@PDA nanozyme exhibited notable peroxidase mimetic enzyme activity. The colorimetric biosensor developed for V. parahaemolyticus detection demonstrated good sensitivity, with a detection range spanning from 2.1 × 101 to 2.1 × 106 CFU/mL, and a limit of detection of 21 CFU/mL. Moreover, the biosensor demonstrated remarkable specificity, achieving good recovery rates from 95.80% to 103.80% in Penaeus vannamei with a relative standard deviation of less than 1.38%. The newly developed colorimetric biosensor offers a remarkable opportunity for the accurate and sensitive detection of V. parahaemolyticus in seafood.

Advancements and Applications of Single-Atom Nanozymes in Sensing Analysis

Single-atom nanozymes, with their atomically dispersed metal active sites, distinctive atom utilization rate, and tunable electronic structure, demonstrate great promise in the field of sensing analysis. This paper reviews the latest research progress on single-atom nanozymes in sensing applications. We classify single-atom nanozymes based on both their structural characteristics, such as carbon-based carriers, frameworks and their derivatives, metal oxides, metal sulfides, and organic polymer carriers, and their unique catalytic properties, including peroxidase, oxidase, catalase, superoxide dismutase, and multi-enzyme mimetic activities. Furthermore, we discuss the application of single-atom nanozymes in the sensitive detection of biological small molecules, antioxidants, ions, enzyme activities and their inhibitors, as well as cells and viruses. Finally, we highlight the opportunities and challenges for advancing the practical application and further research of single-atom nanozymes in the field of sensing analysis.

Paper immobilized BSA-decorated gold nanoclusters for single-step optical sensing of glucose and cholesterol without cross-reactivity

Minimally invasive methods for detecting glucose, cholesterol and hydrogen peroxide are crucial for monitoring the nutritional and health status of humans and animals. The peroxidase mimetic activity by nanozymes is one of the versatile methods for detecting glucose, cholesterol, hydrogen peroxide, and other biomolecules. However, the strict requirement of acidic pH limits their sensing and interfacing ability with natural enzymes. The present study developed bovine serum albumin (BSA) coated gold nanoclusters (AuNC) immobilized on paper fabric to enable single-step visual detection of glucose, cholesterol and hydrogen peroxide in complex biological fluids like serum and milk. The BSA-AuNC suspension and immobilized paper fabric synergistically interface with the natural oxidative enzymes, glucose oxidase or cholesterol oxidase, at physiological pH. The concomitant loss in the fluorescent intensity of BSA-AuNC-loaded paper fabric exposed to the generated hydrogen peroxide (glucose/glucose oxidase or cholesterol/cholesterol oxidase) was directly proportional to the concentration of glucose or cholesterol. These reactions enabled simple visual detection as well as quantification of hydrogen peroxide, glucose and cholesterol using Image-J software and common smartphone-based mobile applications. The detection ability of BSA-AuNC-embedded paper fabric is specific and remains unaltered in the presence of similar oxidase enzymes or similar substrate analogues. With these unique features, the BSA-AuNC embedded paper fabric stands out as a prominent analytical device with enormous potential as a simple, user-friendly detection tool for monitoring biomolecules that are important to health, nutrition, and environmental safeguarding.

Tungsten-rosmarinic acid nanoenzyme with SOD mimetic activity for the treatment of psoriasis by eliminating ROS and relieving inflammation

Psoriasis is a refractory skin disease that seriously affects the physical and mental health of patients. It is easy to relapse and cannot be cured, which seriously harms the physical and mental health of patients. Oxidative stress, driven by increased reactive oxygen species (ROS), plays a critical role in excessive keratinocyte proliferation and local inflammation in psoriasis. In this study, we successfully synthesized a tungsten-rosmarinic acid nanoenzyme (WRA-PEG), which demonstrates promising therapeutic potential for psoriasis. Our findings demonstrate that WRA-PEG effectively scavenges ROS, reduces the proliferation of keratinocytes, and mitigates the release of pro-inflammatory cytokines in vitro. In a psoriasis-like mouse model induced by imiquimod (IMQ), WRA-PEG significantly improved clinical manifestations and prevented recurrence, as evidenced by reduced epidermal thickness and inhibited inflammatory cytokine expression, outperforming traditional treatments like Benvitimod. Bioinformatics analysis revealed the modulation of key inflammatory and oxidative stress-related pathways, highlighting the involvement of crucial genes such as CCL20 and TNFSF10 in its mechanism of action. Furthermore, WRA-PEG exhibited excellent biocompatibility and stability without adverse effects on liver or kidney function. These results underscore the potential of WRA-PEG as a novel therapeutic strategy for managing psoriasis.

Hydroxyl functionalized hexagonal boron nitride quantum dots as nanozyme for pesticides sensing through dual colorimetric and fluorometric platform: A combined experimental and theoretical study

The Hydroxyl-functionalized hexagonal boron nitride quantum dots (h-BN QDs) were synthesized using a hydrothermal technique in a water medium, exhibiting stability in water for over 90 days. The present study demonstrates two simple fluorescence and colorimetric techniques for sensing organophosphorus (OP) and organochloride (OC) pesticides (atrazine, simazine and chlorpyrifos) in an aqueous medium using hydroxyl-functionalized h-BN QDs. The sensing capability of h-BN QDs for these pesticides was determined to be in the range of 5–10 µM using both techniques. The hydroxyl groups on the surface of the QDs enhanced dispersibility and enabled peroxidase-like catalytic activity in acidic conditions. The radical generation using hydroxyl-functionalized h-BN QDs in the presence of H2O2 upon 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) oxidation plays a significant role in the peroxidase reaction. The hydrogen bonding and π-π interactions between the pesticide molecules and ABTS can enhance the pesticide sensing performance. The limit of detection (LOD) using ABTS for atrazine, simazine, and chlorpyrifos was 6.11, 6.56, and 2.47 µM, respectively. Fluorescence sensing, based on a turn ON/OFF mechanism, demonstrated high specificity and sensitivity with LODs of 5.59, 6.45, and 8.08 µM for the same pesticides. The DFT studies revealed non-covalent bonding, such as hydrogen bonding, π-π interactions between the pesticides and the h-BN QDs, indicating binding affinities and stabilization energies of the complexes which can detect pesticides effectively. Atrazine exhibited higher binding affinity towards h-BN QDs, followed by simazine and chlorpyrifos. The h-BN QDs provide a new insight into bonding with pesticides, enhancing the peroxidase mimetic and fluorescence activity.

Diabetic Microenvironment‐Unlocked BioHJzyme with H2S Evolution for Robust Anti‐Pathogens and Hyperinflammatory Wound Regeneration Through TGF‐β/Smad Pathway

AbstractDeferred diabetic skin healing is an ever‐growing complication owing to the hyperglycemic microenvironment, which accelerates the generation of advanced glycated end products (AGEs) and provides a hotbed for pathogenic infection. Here, the H2S‐evolving bio‐heterojunction enzyme (BioHJzyme), which is consisted by MXene/FeS2 and glucose oxidase (GOx) is devised. It presents glutathione peroxidase (GPx)‐ and peroxidase (POD)‐mimetic antibacterial activity for anti‐pathogens and wound regeneration by AGEs depression. The GOx catalyzes glucose, resulting in reducing the bacterial nutrient and supplying H2O2. The POD‐mimetic activity of the BioHJzyme catalyzes the H2O2 to hydroxyl radical (•OH) with a turnover number of 4.45 × 10−1 s−1, while the GPx‐mimetic activity of it consumes glutathione for further •OH accumulation. The anti‐pathogens can be enhanced by near infrared laser (NIR) irradiation owing to the efficient separation of electron‐hole pairs originated from the heterostructure, which presents NIR‐activatable •OH and 1O2 production. Moreover, the BioHJzyme evolves H2S in acidic environment, acting as an H2S donor, which protects cells around the wound from oxidative damage and AGEs, rescues mitochondrial respiration, improves the extracellular matrix deposition and ameliorates dysfunction of fibroblasts for diabetic skin regeneration through TGF‐β/Smad pathway. The work provides a proof‐of‐concept for bacteria‐invaded diabetic wound regeneration via H2S‐evolving BioHJzyme.

Insights into the Theranostic Activity of Nonoxido VIV: Lysosome-Targeted Anticancer Metallodrugs.

Developing new anticancer agents can be useful, with the ability to diagnose and treat cancer worldwide. Previously, we focused on examining the effects of nonoxidovanadium(IV) complexes on insulin mimetic and cytotoxicity activity. In this study, in addition to the cytotoxic activity, we evaluated their bioimaging properties. This study investigates the synthesis of four stable nonoxido VIV complexes [VIV(L1-4)2] (1-4) using aroylhydrazone ligands (H2L1-4) and their full characterization in solid state and the solution phase stability using various physicochemical techniques. The biomolecular (DNA/HSA) interaction of the complexes was evaluated by using conventional methods. The in vitro cytotoxicity of 1-4 was studied against A549 and LN-229 cancer cell lines and found that drug 2 displayed the highest activity among the four. Since 1-4 are fluorescently active, live cell imaging was used to evaluate their cellular localization activity. Complexes specifically target the lysosome and damage lysosome integrity by producing an excessive amount (9.7-fold) of reactive oxygen species (ROS) compared to the control, which may cause cell apoptosis. Overall, this study indicates that 2 has the greatest potential for the development of multifunctional theranostic agents that combine imaging capabilities and anticancer properties of nonoxidovanadium(IV)-based metallodrugs.

Photothermal amplified multizyme activity for synergistic photothermal-catalytic tumor therapy

Nano-enzymatic catalytic therapy has been widely explored as a promising tumor therapeutic method with specific responsiveness to the tumor microenvironment (TME). However, the inherent lower and simplex catalytic efficiency impairs their anti-tumor efficacy. Therefore, developing novel nanozymes with relatively high and multiple catalytic characteristics, simultaneously enhancing the enzyme-like activity of nanozymes using the proper method, photothermal promoted catalytic property, is a reliable way. In this paper, we report a manganese oxide/nitrogen-doped carbon composite nanoparticles (MnO-N/C NPs) with multi-enzyme mimetic activity and photothermal conversional effect. The peroxidase (POD)-like/oxidase (OXD)-like/catalase (CAT)-like activity of MnO-N/C nanozymes was accelerated upon exposure to an 808 nm NIR laser. In vitro and in vivo results proved that the MnO-N/C NPs shown excellent magnetic resonance imaging (MRI) guided synergistic photothermal-enhanced catalytic treatment and photothermal therapy of liver cancer. The photothermal enhanced multi-enzyme activity maximizes the efficacy of catalytic and photothermal therapy while reducing harm to healthy cells, thereby offering valuable insights for the development of next-generation photothermal nanozymes to enhance tumor therapy.

A sensitive Fe3O4@MnO2 nanocatalyst designed for visual determination of total antioxidant capacity in fruit juice

Fruit juice is kind of popular beverage food worldwidely, and its total antioxidant capacity (TAC) is generally considered as an important index for people’s rational diet, thus accurate evaluation of its TAC is essential for human health guidance. Herein, we constructed a sensitive Fe3O4@MnO2 nanocatalyst that was delicately cored with magnetite nanoparticles (Fe3O4 NPs) and encapsulated with manganese dioxide (MnO2) nanoshells for fast and accurate TAC colorimetric analysis in fruit juice. The data showed the fabricated Fe3O4@MnO2 nanocatalysts performed with remarkable oxidase mimetic activities and could catalyze oxidization of colorimetric substrate without additional H2O2, and the limit of detection (LOD) was about 0.39 μM for ascorbic acid (AA) evaluation. Applied in commercial fruit juice products, the fabricated Fe3O4@MnO2 nanocatalysts showed a reliable and visual assessment for the accurate TAC analysis. In addition, the fabricated Fe3O4@MnO2 nanocatalysts could be easily recycled due to their intrinsic superparamagnetic property. Together, an intellegent Fe3O4@MnO2 nanocatalyst was well developed for visual TAC analysis in fruit juice with convenient applications in future.

High-loading ficin@AuNPs on polymer-UiO-66 surface with enhanced peroxidase-mimetic catalytic activity for colourimetric detection of dopamine.

Recently, MOFs@AuNPs composites-based catalysts via anchoring of AuNPs onto metal-organic-frameworks (MOFs) have attracted great attention. However, the influence of the AuNPs loading amounts on the catalytic activity of MOFs@AuNPs composites remains largely unexplored. Here, ficin (Fic) protected AuNPs (Fic@AuNPs) anchored onto the surface of UiO-66-NH2 (UiO) modified with poly(2-vinyl-4,4-dimethyl-2-oxazolidine) (PV) were designed and constructed. The UiOPVFic@AuNPs composites with longer PV chains leading to high-loading Fic@AuNPs exhibited intense peroxidase (POD)-mimetic activity in 3,3'5,5'-tetramethylbenzidine (TMB) oxidation. Further, following the colour-fading, dopamine (DA) was sensitively and selectively monitored in the composites-TMB-H2O2 system. The portable smartphone sensing platform-based colourimetric method had good linearity ranging from 3.34 to 36.7μM (R2 = 0.995), with a limit of detection of 0.3μM. This protocol explores high-loading AuNPs on polymer-MOFs composites, providing deep insights into understanding catalytic activity improvements of polymer-MOFs@AuNPs catalysts and revealing their application potential in real biological samples analysis.

Single-stranded DNA regulated peroxidase mimetic activity of MCOF@AuNPs for colorimetric detection of carcinoembryonic antigen

Rapid, accurate, simple and portable monitoring of carcinoembryonic antigen (CEA) in serum is important for assessing the occurrence, development, and prognosis of cancer. In this work, we developed a colorimetric method based on the peroxidase-like activity of MCOF@AuNPs functionalized by complementary sequences of CEA-specific aptamer (MCOF@AuNPs-apt*) enhancing by G-terminated CEA-specific aptamer (G-apt). The enhancement of catalytic activity depends on the increase affinity of MCOF@AuNPs-apt*-G-apt to the TMB via promoting electron transfer. Based on this strategy, we successfully detected CEA at 0.1 ng/mL with high accuracy and anti-interference ability. Importantly, combined with the smartphone app based on the smartphone app RGB color model, the results can be visualized directly without expensive equipment, which meets the demand for point of care testing of CEA. This study also explored the enhancement of catalytic activity of nanozyme by ssDNA and the application potential in aptamer biosensor.

Mn‐functionalized ZIF‐67 for Sensitive Colorimetric Detection of Artemisinin and Ascorbic Acid

AbstractArtemisinin (Art) is the first‐choice medicine for treating malaria. It also shows good therapeutic effects in antibacterial and antitumor treatment. Therefore, a simple and efficient method for detecting Art is of great significance. Mn‐functionalized ZIF‐67 (Mn@ZIF‐67) hybrid materials were synthesized using a post‐synthesis modification method. Due to the introduction of Mn2+, Mn@ZIF‐67 possesses higher peroxidase/oxidase like dual‐mimic enzymes activity than ZIF‐67, which can catalyze Art and generate peroxyl radicals. Based on this fact, Mn@ZIF‐67 was used to detect Art in the presence of TMB. A good linear relationship between absorption intensities at 652 nm and Art concentrations was obtained in the range of 0–22 μM with a detection limit of 200 nM. Ascorbic acid (AA), due to its reducibility, can inhibit peroxidase/oxidase mimetics activity of Mn@ZIF‐67 and the blue Mn@ZIF‐67‐TMB solution fades gradually with the addition of AA. Mn@ZIF‐67‐TMB acting as a colorimetric sensor, AA can be sensitively detected ranging from 0–30 μM, and the detection limit is 50 nM. Coexisting substances don't interfere with the detection of Art or AA. This sensing platform provides a highly sensitive and selective colorimetric method for monitoring AA and Art in serum, thereby demonstrating remarkable practicality.

Portable multimodal platform with carbon nano-onions as colorimetric and fluorescent signal output for trypsin detection

Multimodal biosensors with independent signaling pathways can self-calibrate and improve the reliability of disease biomarker detection. Herein, a colorimetric-fluorescent dual-mode paper-based biosensor with PAN/Fe(III)–CNOs (FPCs) as core components has been developed, which information is recognized by smartphone and naked eye. Using 1-(2-pyridylazo)-2-naphthol (PAN) as a mediator, Fe(III) is enriched on the surface of carbon nano-onions (CNOs), endowing FPCs with excellent mimetic enzyme activity and photothermal conversion ability, which allows it to output amplified colorimetric signals under laser irradiation. In addition, the complexation of PAN with Fe(III) broadens its absorption spectrum, which makes FPCs more suitable to be energy acceptors to quench fluorescence of polymer dots (Pdots), resulting in the changes of output fluorescent signal. Based on the above design, a portable colorimetric-fluorescent dual-mode biosensor is proposed for trypsin detection with Pdots as fluorescence sources and FPCs as fluorescence quenchers and nanoenzymes. This work provides a convenient way for constructing portable visual multimodal biosensors, which is expected to applied in various disease diagnosis.

Nanoscale mineral as a novel class enzyme mimic (mineralzyme) with total antioxidant capacity detection: Colorimetric and smartphone-based approaches

Nanozymes, synthetic nano-scale materials with enzyme-like behavior, have shown remarkable advancements and widespread utilization across various applications. However, the majority of nanozymes require precursor of synthetic-chemicals, which are sometimes expensive and undergo complicated preparations and tedious purification procedures. Therefore, it is of utmost significance to find an enzyme mimic that is affordable, abundant, highly efficient, and sustainable for various applications in biomedicine, environmental sciences, and the food industry. We prove the efficient peroxidase-like activities of the earthly available mineral, barunite-II. The braunite-II mineral micro-nanoparticles (NB) were prepared via physical milling. The enzyme mimetic activity of mineral nanoparticles, referred to as “mineralzyme,” could oxidize the chromogenic blue color of TMB (3,3′,5,5′-tetramethylbenzidine) to oxTMB (3,3′,5,5′-tetramethylbenzidine oxide). Michaelis-Menten constant (Km) and maximum velocity (Vmax) were 135 mM and 62.73 mM min−1 for TMB as a substrate, 139.2 mM, and 2.69 mM min−1 for H2O2 as a substrate. The Km values are much lower than those for HRP. We accurately quantified the total antioxidant capacity in seminal fluid samples from infertile patients using the peroxidase activity of the mineral nanoparticles. This investigation will open new avenues to explore the realm of mineralzyme, revealing its significant potential for a wide range of applications involving diverse enzymatic behaviors.

Azologs of the Fatty Acid Mimetic Drug Cinalukast Enable Light-Induced PPARα Activation.

Photo-switchable nuclear receptor modulators ("photohormones") enable spatial and temporal control over transcription factor activity and are valuable precision tools for biological studies. We have developed a new photohormone chemotype by incorporating a light-switchable motif in the scaffold of a cinalukast-derived PPARα ligand and tuned light-controlled activity by systematic structural variation. An optimized photohormone exhibited PPARα agonism in its light-induced (Z)-configuration and strong selectivity over related lipid-activated transcription factors representing a valuable addition to the collection of light-controlled tools to study nuclear receptor activity.

Enzyme Mimetic Activity of Intercalated Pd–H Nanosheets for Bioanalysis

Enzyme Mimetic Activity of Intercalated Pd–H Nanosheets for Bioanalysis

Enhanced oxidoreductase activity of diatom frustule supported Fe3O4 for sensitive colorimetric detection of Cr(VI)

Given Cr(VI) is a ubiquitous water pollutant posing significant public health risks, there is a need for an inexpensive and easy-to-use detection tool. Herein, a diatom frustule-supported Fe3O4 (DF-Fe3O4) with enhanced oxidoreductase mimetic activity is reported for direct colorimetric detection of Cr(VI). Unlike the peroxidase nanozymes which are often reported for colorimetric detection, DF-Fe3O4 triggered a chromogenic redox reaction between TMB and Cr(VI) without requiring H2O2. This enables direct redox reactions while circumventing potential interferences associated with the use of H2O2. DF-Fe3O4 was synthesized with a coprecipitation method and subsequently characterized by SEM, XRD, and XPS techniques, revealing the distribution of Fe3O4 NPs on the frustule matrix. The frustule obtained from Nitzschia sp. of a sediment sample rendered a robust catalytic support enhancing the oxidoreductase activity of pristine Fe3O4 NPs by 20.8 %. Further, the nanozyme maintains 73 % of its activity even at 95 °C while losing only 33 % of its activity after one month of storage. The oxidoreductase mimetic activity was evaluated using the chromogenic redox reaction between TMB and Cr(VI) which rapidly forms a blue color (λmax= 654 nm), where its intensity forms the basis of the colorimetric detection. With a Km value of 0.058 mM, the nanozyme was able to selectively detect Cr(VI) down to 0.21 µM with a linear range between 0.1–500 µM. Recoveries from spiked wastewater samples were between 91.14–102.20 %. The obtained analytical figures of merits demonstrated the applicability of the developed sensor for Cr (VI) analysis devoid of complex instrumentation in the established analytical methods.