H2O2-sensitive quantum dots for the label-free detection of glucose

A novel label-free detection system based on CdTe/CdS quantum dots (QDs) was designed for the direct measurement of glucose. Herein we demonstrated that the photoluminescence (PL) of CdTe/CdS QDs was sensitive to hydrogen peroxide (H₂O₂). With d-glucose as a substrate, H₂O₂ that intensively quenched the QDs PL can be produced via the catalysis of glucose oxidase (GOx). Experimental results showed that the decrease of the QDs PL was proportional to the concentration of glucose within the range of 1.8 μM to 1 mM with the detection limit of 1.8 μM under the optimized experimental conditions. In addition, the QD-based label-free glucose sensing platform was adapted to 96-well plates for fluorescent assay, enhancing the capabilities and conveniences of this detection platform. An excellent response to the concentrations of glucose was found within the range of 2-30 mM. Glucose in blood and urine samples was effectively detected via this strategy. The comparison with commercialized glucose meter indicated that this proposed glucose assay system is not only simple, sensitive, but also reliable and suitable for practical application. The high sensitivity, versatility, portability, high-throughput and low cost of this glucose sensor implied its potential in point-of-care clinical diagnose of diabetes and other fields.     

Paper-based fluorescent devices for multifunctional assays: Biomarkers detection,inhibitors screening and chiral recognition

The development of a single analytical platform with different functions is highly desirable but remains a challenge at present. Here, a paper-based device based on fluorescent carbon dots (CDs) functionalized paper/MnO₂ nanosheets (MnO₂ NS) hybrid devices (PCD/NS) was proposed for single-device multi-function applications. MnO₂ NS functioned as a fluorescence quencher of CDs and recognizer of H₂O₂ released from the oxidase catalyzed system. Fluorescence recovery would occur after the decomposition of MnO₂ NS induced by H₂O₂, by which a simple and effective strategy could be developed for fluorescence monitoring multiplex biological events. Xanthine (XA) sensing, xanthine oxidase (XOD) inhibitors screening analysis and chiral recognition of glucose enantiomers were performed on PCD/NS to investigate the multifunctional application of the paper-based device. By means of PCD/NS, XA could be determined in the range of 0.1–40 µmol/L with a low detection of limit of 0.06 µmol/L. The IC₅₀ value of allopurinol, the model inhibitor of XOD, was sensitively detected to be 7.4 µmol/L. Glucose enantiomers were also recognized in terms of the specific fluorescence response to d-glucose. This work firstly presented a paper-based device capable of biomarkers detection, inhibitors screening and chiral recognition, which enlightened a promising strategy for the construction of multifunctional devices and hold the great potential application in clinical diagnosis and drug discovery.     

Glutathione-capped CdTe quantum dots for the sensitive detection of glucose

A simple and sensitive assay system for glucose based on the glutathione (GSH)-capped CdTe quantum dots (QDs) was developed. GSH-capped CdTe QDs exhibit higher sensitivity to H₂O₂ produced from the glucose oxidase catalyzed oxidation of glucose, and are also more biocompatible than other thiols-capped QDs. Based on the quenching of H₂O₂ on GSH-capped QDs, glucose can be detected. The detection conditions containing reaction time, the concentration of glucose oxidase and the sizes of QDs were optimized and the detection limits for glucose was determined to be 0.1 μM; two detection ranges of glucose from 1.0 μM to 0.5 mM and from 1.0 mM to 20 mM, respectively were obtained. The detection limit was almost a 1000 times lower than other QDs-based optical glucose sensing systems. The developed glucose detection system was simple and facile with no need of complicated enzyme immobilization and modification of QDs.     

Prussian Blue Nanocubes‐SnO2 Quantum Dots‐Reduced Graphene Oxide Ternary Nanocomposite: An Efficient Non‐noble‐metal Electrocatalyst for Non‐enzymatic Detection of H2O2

Developing non‐noble‐metal electrocatalyst for non‐enzymatic H₂O₂ sensing is highly attractive. A facile, two‐step approach has been utilized for the synthesis of PBNCs/SnO₂ QDs/RGO ternary nanocomposite. TEM, SEM, XPS, and XRD techniques were used to the characterize the structural and morphological properties of synthesized ternary nanocomposite. The synthesized ternary nanocomposite has been examined as an electrode material for the electrochemical detection of H₂O₂ using the Amperometry technique. Under optimum conditions, PBNCs/SnO₂ QDs/RGO ternary nanocomposite performed very well in the electrocatalytic reduction of H₂O₂ with a linear dynamic range from 25–225 μM (R²=0.996) with a low detection limit of 71 nM (S/N=3). Compared to the recent literature, PBNCs/SnO₂QDs/RGO ternary nanocomposite based modified electrode exhibit a wider linear dynamic range with a low detection limit. Furthermore, PBNCs/SnO₂ QDs/RGO ternary nanocomposite based modified electrode showed an excellent anti‐interference ability against various common interfering agents. The practical applicability of this ternary nanocomposite based modified electrode was further extended to determine the H₂O₂ in tap water with acceptable recovery. The present performance of PBNCs/SnO₂ QDs/RGO ternary nanocomposite material towards H₂O₂ sensing might widen its application for developing a new type of non‐noble metal‐based non‐enzymatic electrochemical biosensors.     

2D/2D h‐BN/N‐doped MoS2 Heterostructure Catalyst with Enhanced Peroxidase‐like Performance for Visual Colorimetric Determination of H2O2

Recently, nanozymes have attracted extensive attention because of their advantages of combining nanomaterials with enzymes. Herein, hexagonal boron nitride (h‐BN) and nitride‐doped molybdenum disulfide (N?MoS₂) nano‐composites (h‐BN/N?MoS₂) were synthesized by facile and cost‐effective liquid exfoliation with a solvothermal method in nontoxic ethanol solution. The results show that h‐BN, as a co‐catalyst, can not only dope into the lattice of MoS₂ but also form a heterogeneous structure with MoS₂NSs. It expanded the layer spacing and specific surface area of MoS₂NSs, which was beneficial to the contact between the catalyst and the substrate, and resulted in a synergistic enhancement of the catalytic activity of hydrogen peroxide (H₂O₂) with MoS₂. A colorimetric determination platform of h‐BN/N?MoS₂‐TMB‐H₂O₂ was constructed. It exhibited a wide linear range of 1–1000 μM with a low limit of detection (LOD) of 0.4 μM under optimal conditions, high sensitivity and stability, as well as good reliability (99.4–110.0%) in practice, making the measurement system more widely applicable.1. Introduction     

A Novel Hydrogen Peroxide Amperometric Sensor Based on Hierarchical 3D Porous MnO2−TiO2 Composites

A novel nanocomposite electrode based on hierarchical 3D porous MnO₂?TiO₂ for the application in hydrogen peroxide (H₂O₂) sensors has been explored. This electrode was fabricated by growing TiO₂ cross‐linked nanowires on a commercial fluorine tin oxide (FTO) glass via a hydrothermal process and subsequent deposition of 3D honeycomb‐like MnO₂ nanowalls using an electrodeposition method (denoted as 3D MNS‐TNW@FTO). The obtained 3D MNS‐TNW@FTO electrode was characterized by scanning electron microscopy (SEM), Raman spectroscopy, X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). Based on such a unique 3D porous framework and the existence of MnO₂, the electrode demonstrates a good performance in the detection of H₂O₂, with two linear ranges from 9.8 to 125 μM and 125 μM–1.0 mM, a good selectivity of 8.02 μA mM^?1 cm^?2, and a low detection limit of 4.5 μM. In addition, the simplicity of the developed low‐cost fabrication process provides an efficient method for the mass production of electrocatalytical MnO₂?TiO₂ nanocomposites on commercial FTO glass for H₂O₂ sensing applications and can be adapted for other electrochemical sensors for various biochemical targets. It thus is beneficial for the practical usage in bioanalysis.     

Three-dimensional porous reduced graphene oxide decorated with MoS2 quantum dots for electrochemical determination of hydrogen peroxide

Three-dimensional (3D) graphene-based nanomaterials have shown wide applications in electrochemical fields such as biosensors. In this study, we displayed a simple fabrication of 3D structural reduced graphene oxide (3D structural RGO) decorated with molybdenum disulfide quantum dots (MoS₂QDs) through a three-step reaction process. With its abundant raw materials, this strategy is economic and non-toxic. Various characterization techniques were utilized to characterize the morphologies of the synthesized MoS₂QDs, graphene oxide (GO), and 3D structural RGO-MoS₂QDs composites. Simultaneously, X-ray photoelectron spectroscopy was applied to characterize the structure and properties of composites. In order to understand the effects of the reaction period on the structure of 3D structural RGO-MoS₂QDs, a series of samples with various reaction periods were prepared for morphological characterization. Finally, the fabricated 3D structural RGO-MoS₂QDs composites were used to modify a glassy carbon electrode as an electrochemical non-enzymatic hydrogen peroxide (H₂O₂) sensor. The obtained results indicate that the fabricated electrochemical H₂O₂ sensor exhibits a wide detection range (0.01–5.57 mM), low detection limit (1.90 μM), good anti-interference performance, and long-time stability (18 days).     

A sensitive electrochemical aptasensor based on palladium nanoparticles decorated graphene–molybdenum disulfide flower-like nanocomposites and enzymatic signal amplification

In the present study, with the aggregated advantages of graphene and molybdenum disulfide (MoS₂), we prepared poly(diallyldimethylammonium chloride)–graphene/molybdenum disulfide (PDDA–G–MoS₂) nanocomposites with flower-like structure, large surface area and excellent conductivity. Furthermore, an advanced sandwich-type electrochemical assay for sensitive detection of thrombin (TB) was fabricated using palladium nanoparticles decorated PDDA–G–MoS₂ (PdNPs/PDDA–G–MoS₂) as nanocarriers, which were functionalized by hemin/G-quadruplex, glucose oxidase (GOD), and toluidine blue (Tb) as redox probes. The signal amplification strategy was achieved as follows: Firstly, the immobilized GOD could effectively catalyze the oxidation of glucose to gluconolactone, coupling with the reduction of the dissolved oxygen to H₂O₂. Then, both PdNPs and hemin/G-quadruplex acting as hydrogen peroxide (HRP)-mimicking enzyme could further catalyze the reduction of H₂O₂, resulting in significant electrochemical signal amplification. So the proposed aptasensor showed high sensitivity with a wide dynamic linear range of 0.0001 to 40 nM and a relatively low detection limit of 0.062 pM for TB determination. The strategy showed huge potential of application in protein detection and disease diagnosis.     

MnO<Subscript>2</Subscript> Nanoparticles and Carbon Nanofibers Nanocomposites with High Sensing Performance Toward Glucose

By combining the advantages of manganese dioxide nanoparticles (MnO₂ NPs) and carbon nanofibers (CNFs), a biosensing electrode surface as a high-performance enzyme biosensor is designed in this work. MnO₂ NPs and CNFs nanocomposites (MnO₂–CNFs) were prepared by using a simple hydrothermal method and then were characterized by scanning electron microscopy, powder X-ray diffraction, fourier transform infrared spectroscopy, energy dispersive spectrometry and electrochemisty. The results showed that MnO₂ NPs are uniformly attached to the surface of CNFs. Meanwhile, the MnO₂–CNFs nanocomposites as a supporting matrix can provide an efficient and advantageous platform for electrochemical sensing applications. On the basis of the improved sensitivity of MnO₂–CNFs modified electrode toward H₂O₂ at low overpotential, a MnO₂–CNFs based glucose biosensor was fabricated by monitoring H₂O₂ produced by an enzymatic reaction between glucose oxidase and glucose. The constructed biosensor exhibited a linear calibration graph for glucose in a concentration range of 0.08–4.6 mM and a low detection limit of 0.015 mM. In addition, the biosensor showed other excellent characteristics, such as high sensitivity and selectivity, short response time, and the relative low apparent Michaelis–Menten constant. Analysis of human urine spiked with glucose at different concentration levels yielded recoveries between 101.0 and 104.8%.     

Electro Catalytic Properties of α, β, γ, ϵ ‐ MnO2 and γ ‐ MnOOH Nanoparticles: Role of Polymorphs on Enzyme Free H2O2 Sensing

Polymorphs of Manganese di oxide (MnO₂) such as alpha (α), beta (β), gamma (γ), epsilon (ϵ), and MnOOH type materials were prepared via hydrothermal approach under different conditions. The samples were characterized by XRD, FESEM, FT‐IR, Raman and BET analysis. Cyclic voltammetry (CV) analysis confirm that α ‐ MnO₂ shows better electro‐catalytic ability. Amperometry sensing of hydrogen peroxide (H₂O₂) was carried out by varying applied potential value with the polymorphs of MnO₂. Compared with the other phases of MnO₂, α ‐ MnO₂ shows high linear range up to 20μM. The calculated sensitivity value for H₂O₂ sensing of different phases is in the order of α ‐ MnO₂, β ‐ MnO₂, ϵ ‐ MnO₂, γ ‐ MnO_2, MnOOH and found to be 0.094 mA μM⁻¹ cm⁻² > 0.072 mA μM⁻¹ cm⁻² > 0.07 mA μM⁻¹ cm⁻² > 0.03 mA μM⁻¹ cm⁻² > 0.01 mA μM⁻¹ cm⁻² respectively. All the characterization results reveal that crystalline phase plays a vital role in electrochemical behavior rather than crystalline size, morphology, surface charge, surface area.     

Enhanced peroxidase-like activity of hierarchical MoS_2-decorated N-doped carbon nanotubes with synergetic effect for colorimetric detection of H_2O_2 and ascorbic acid

The exploitation of multifunctional nanocomposites is highly desired in environmental monitoring,biosensors,and medical diagnosis.In this paper,a simple approach has been proposed to fabricate MoS_2 decorated N-doped carbon nanotubes(NCNTs@MoS_2) hybrid composites as efficient peroxidase-like mimics.The combination of the MoS_2 and N-doped carbon nanotubes(NCNTs) brings about an enhanced synergistic effect,leading to remarkably decent intrinsic peroxidase-mimic activities than that of the single components.Due to the high catalytic efficiency of the resultant NCNTs@MoS_2 hybrid nanotubes as peroxidase-like mimics,a co nvenient colorimetric approach for the sensitive determination of H_2 O_2 and ascorbic acid have been developed with a detection limit of about 0.14 μmol/L and 0.12 μmol/L,respectively.The work offers a new strategy for the fabrication of peroxidase-like nanomaterials with excellent catalytic activity,which indicates great promising applications in sensitive detections in real samples.     

Synthesis of Ag Nanoparticle Doped MnO2/GO Nanocomposites at a Gas/Liquid Interface and its Application in H2O2 Detection

Ag/MnO₂/GO nanocomposites were synthesized via the method of gas/liquid interface based on silver mirror reaction, and a non‐enzymatic H₂O₂ sensor was fabricated through immobilizing Ag/MnO₂/GO nanocomposites on GCE. The composition and morphology of the nanocomposites were studied by energy‐dispersive X‐ray spectroscopy (EDS), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Electrochemical investigation indicated that it exhibited a favorable performance for the H₂O₂ detection. Its linear detection range was from 3 μM to 7 mM with a correlation coefficient of 0.9960; the sensitivity was 105.40 μA mM^?1 cm^?2 and the detection limit was estimated to be 0.7 μM at a signal‐to‐noise ratio of 3.     

利用AgVO3改性MoS2增强活性氧产生及其光催化性能的提高

随着全球工业化进程的发展,环境污染问题日益严重,已经成为21世纪影响人类生存与发展的重要问题.光催化氧化技术被认为是解决环境问题最有应用前景的技术之一,已经成为环境领域的研究热点.众所周知,二硫化钼(MoS2)可以被可见光激发产生电子-空穴对,但是由于其氧化还原电势并不高,抑制了氧分子活化的量子效率,且激发后的光生载流子容易复合,导致光催化效率不高.因此,迫切需要对MoS2光催化材料进行修饰与改性,采用提高光催化过程中活性氧(ROSs)的量来提高其光催化活性.银钒氧化物(AgVO3,Ag2V4O11,Ag3VO4和Ag4V2O7等)因其在锂电池、传感器和光催化剂领域的应用而引起了人们的关注.其中,AgVO3具有较窄的带隙和高度分散的价带,具有潜在的应用价值.本文采用水热法成功制备了AgVO3/MoS2复合光催化剂,并采用X射线粉末衍射、扫描电子显微、透射电子显微镜和紫外-可见漫反射光谱等表征技术研究了所制光催化剂的物相结构、样品形貌和光学性能.以四环素为研究对象,将其应用于AgVO3/MoS2复合光催化剂的降解实验.结果表明,随着AgVO3质量比从1.0 wt%增加到3.0 wt%,所得催化剂的光催化活性不断提高;当进一步增加AgVO3的质量时,复合催化剂的活性逐渐降低.这是由于过多的AgVO3的引入导致在光催化剂表面形成电子-空穴对复合中心,增加了载流子复合几率.因此,AgVO3/MoS2复合光催化剂中AgVO3的最佳质量比为3.0 wt%,其降解速率常数为0.0087 min–1,分别是MoS2(0.00509 min–1)和AgVO3(0.00495 min–1)的1.71和1.76倍.由于AgVO3改性后的MoS2具有优异的光催化性能,能促进O2的吸附/活化,加速MoS2表面生成H2O2的双电子氧还原反应,从而产生更多的ROSs.利用电子自旋共振光谱、POPHA荧光检测和自由基捕获实验相结合的方法来阐明ROSs的形成机理.同时,ROSs的产生会加速消耗AgOV3导带上的电子,为降解污染物留下更多的空穴.本文为表面催化工程促进ROSs生成的合理设计提供了新的思路,有望在环境治理中得到实际应用.     

Fluorometric method for the determination of hydrogen peroxide and glucose with Fe3O4 as catalyst

In this paper, we utilized the instinct peroxidase-like property of Fe₃O₄ magnetic nanoparticles (MNPs) to establish a new fluorometric method for determination of hydrogen peroxide and glucose. In the presence of Fe₃O₄ MNPs as peroxidase mimetic catalyst, H₂O₂ was decomposed into radical that could quench the fluorescence of CdTe QDs more efficiently and rapidly. Then the oxidization of glucose by glucose oxidase was coupled with the fluorescence quenching of CdTe QDs by H₂O₂ producer with Fe₃O₄ MNPs catalyst, which can be used to detect glucose. Under the optimal reaction conditions, a linear correlation was established between fluorescence intensity ratio I₀/I and concentration of H₂O₂ from 1.8 × 10⁻⁷ to 9 × 10⁻⁴ mol/L with a detection limit of 1.8 × 10⁻⁸ mol/L. And a linear correlation was established between fluorescence intensity ratio I₀/I and concentration of glucose from 1.6 × 10⁻⁶ to 1.6 × 10⁻⁴ mol/L with a detection limit of 1.0 × 10⁻⁶ mol/L. The proposed method was applied to the determination of glucose in human serum samples with satisfactory results.     

A turn-on fluorescence-sensing technique for glucose determination based on graphene oxide–DNA interaction

Graphene is a two-dimensional carbon nanomaterial one atom thick. Interactions between graphene oxide (GO) and ssDNA containing different numbers of bases have been proved to be remarkably different. In this paper we propose a novel approach for turn-on fluorescence sensing determination of glucose. Hydrogen peroxide (H₂O₂) is produced by glucose oxidase-catalysed oxidation of glucose. In the presence of ferrous iron (Fe²⁺) the hydroxyl radical (?OH) is generated from H₂O₂ by the Fenton reaction. This attacks FAM-labelled long ssDNA causing irreversible cleavage, as a result of the oxidative effect of ?OH, producing an FAM-linked DNA fragment. Because of the weak interaction between GO and short FAM-linked DNA fragments, restoration of DNA fluorescence can be achieved by addition of glucose. Due to the excellent fluorescence quenching efficiency of GO and the specific catalysis of glucose oxidase, the sensitivity and selectivity of this method for GO-DNA sensing are extremely high. The linear range is from 0.5 to 10 μmol L^?1 and the detection limit for glucose is 0.1 μmol L^?1. The method has been successfully used for analysis of glucose in human serum. Figure

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Strong enhancement of the chemiluminescence of the Cu(II)-H<Subscript>2</Subscript>O<Subscript>2</Subscript> system on addition of carbon nitride quantum dots,and its application to the detection of H<Subscript>2</Subscript>O<Subscript>2</Subscript> and glucose

The authors report that carbon nitride quantum dots (CN QDs) exert a strong enhancing effect on the Cu(II)/H₂O₂ chemiluminescent system. Chemiluminescence (CL) intensity is enhanced by CN QDs by a factor of ~75, while other carbon nanomaterials have a much weaker effect. The possible mechanism of the effect was evaluated by recording fluorescence and CL spectra and by examining the effect of various radical scavengers. Emitting species was found to be excited-state CN QDs that produce green CL peaking at 515 nm. The new CL system was applied to the sensitive detection of H₂O₂ and glucose (via glucose oxidase-catalyzed formation of H₂O₂) with detection limits (3σ) of 10 nM for H₂O₂ and 100 nM for glucose. The probe was employed for glucose determination in human plasma samples with satisfactory results.

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Graphical abstract The effect of carbon nitride quantum dots (CN QDs) on Cu(II)-H₂O₂ chemiluminescence reaction was studied and the new CL system was applied for sensitive detection of glucose based on the glucose oxidase (GOx)-catalyzed formation of H₂O₂.

     

The Pt-free 1T/2H-MoS2/CdS/MnOx hollow core-shell nanocomposites toward overall water splitting via HER/OER synergy of 1T-MoS2/MnOx

Hydrogen evolution reaction/Oxygen evolution reaction (HER/OER) synergy would be the most important issue for overall water splitting. The Pt-free 1T/2H-MoS₂/CdS/MnO_x hollow core–shell nanocomposites are fabricated via a continuous hydrothermal–chemical method; therefore, the OER co-catalysts MnO_x and CdS shell are deposited on the surface of SiO₂ nanosphere templates continuously via hydrothermal–chemical method. Subsequently, the SiO₂ templates are etched via chemical method and the 2H-MoS₂/CdS hollow core–shell heterojunction and 1T-MoS₂ HER co-catalyst are introduced via one-step hydrothermal method. Evaluated by photocatalytic performance, the 1T/2H-MoS₂/CdS/MnO_x exhibits an enhanced HER performance of about ~50 folds than that of single CdS hollow nanosphere, and achieves a decent overall water splitting performance of about ~1668.00(H₂)/824.61(O₂) μmol/g?h, which can be mainly ascribed to the well HER/OER synergy and formation of hollow core–shell structure. Therefore, the 1T-MoS₂ with quick electron transport and decent solid/liquid interface can promote the photogenerated electron diffusing, the MnO_x with mixed Mn³⁺/Mn⁴⁺ ions can activate the hole-related species for OH^? oxidation and promote H₂O₂ decomposition, the 2H–MoS₂/CdS heterojunction can separate the charge carrier and meet the potential to achieve overall water splitting. Additionally, the 1T/2H-MoS₂ with decent lattice matching can improve the charge carrier transport, the 1T-MoS₂ with sufficient specific surface areas can increase active sites and the hollow core–shell structure can increase solar efficiency which is also beneficial for enhancing the overall water splitting performance and stability.     

Ultrathin FeS nanosheets with high chemodynamic activity for sensitive colorimetric detection of H2O2 and glutathione

Iron chalcogenides have attracted great interest as potential substitutes of nature enzymes in the colorimetric biological sensing due to their unique chemodynamic characteristics.Herein,we report the preparation of ultrathin Fe S nanosheets （NSs） by a simple one-pot hydrothermal method and the prepared Fe S NSs exhibit strong Fenton-reaction activity to catalyze hydrogen peroxide （H₂O₂） for generation of hydroxyl radical （^·OH）.Based on the chromogenic reaction o...     

The Hybrid of Gold Nanoparticles and 3D Flower‐like MnO2 Nanostructure with Enhanced Activity for Detection of Hydrogen Peroxide

3D Flower‐like manganese dioxide (MnO₂) nanostructure with the ability of catalysis for hydrogen peroxide (H₂O₂) and super large area that can support gold nanoparticles (AuNPs) with enhanced activity of electron transfer have been developed. The nanostructure of hybrids was prepared by directly mixing citric‐capped AuNPs and 3‐aminopropyltriethoxysilane (3‐APTES)‐capped nano‐MnO₂ using an electrostatic adsorption strategy. The Au‐MnO₂ composite was extensively characterized by scanning electron microscope (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), the Brunauer‐Emmett‐Teller (BET) method and X‐ray photoemission spectroscopy (XPS). Electrochemical properties were evaluated through cyclic voltammetry (CV) and amperometric method. The prepared sensor showed excellent electrochemical properties towards H₂O₂ with a wide linear range from 2.5×10⁻³∼1.39 mM and 3.89∼13.89 mM. The detection limit is 0.34 μM (S/N=3) with the sensitivities of 169.43 μA mM⁻¹ cm⁻² and 55.72 μA mM⁻¹ cm⁻². The detection of real samples was also studied. The result exhibited that the prepared sensor can be used for H₂O₂ detection in real samples.     

An Enzyme-free Electrochemical H2O2 Sensor Based on a Nickel Metal-organic Framework Nanosheet Array

In this work, we reported the development of a nickel metal-organic framework nanosheet array on Ti-mesh (Ni-MOF/TM) as an enzyme-free electrochemical sensing platform for H₂O₂ determination. The as-obtained sensor exhibited outstanding detection properties of H₂O₂, which might be gifted from the large specific surface area, abundant active sites of Ni-MOF nanoarrays. The sensor displayed a good linear range (0.8 μM–4.6×10³ μM), a detection limit as low as 0.26 μM, a high sensitivity (307.5 μA mM⁻¹ cm⁻²), and a rapid response. Moreover, this enzyme-free sensor is promising for point-of-care (POC) testing of H₂O₂ in human serum attribute to the excellent performance of Ni-MOF and the simple preparation process of the sensor.