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The treatment of wound inflammation is intricately linked to the concentration of reactive oxygen species (ROS) in the wound microenvironment. Among these ROS, H2O2 serves as a critical signaling molecule and second messenger, necessitating the urgent need for its rapid real-time quantitative detection, as well as effective clearance, in the pursuit of effective wound inflammation treatment. Here, we exploited a sophisticated 3D Cu2-xSe/GO nanostructurebased nanonzymatic H2O2 electrochemical sensor, which is further decorated with evenly distributed Pt nanoparticles (Pt NPs) through electrodeposition. The obtained Cu2-xSe/GO@Pt/SPCE sensing electrode possesses a remarkable increase in specific surface derived from the three-dimensional surface constructed by GO nanosheets. Moreover, the localized surface plasma effect of the Cu2-xSe nanospheres enhances the separation of photogenerated electron-hole pairs between the interface of the Cu2-xSe NPs and the Pt NPs. This innovation enables near-infrared light-enhanced catalysis, significantly reducing the detection limit of the Cu2-xSe/GO@Pt/SPCE sensing electrode for H2O2 (from 1.45 mM to 0.53mM) under NIR light. Furthermore, this biosensor electrode enables in-situ real-time monitoring of H2O2 released by cells. The NIR-enhanced Cu2-xSe/GO@Pt/SPCE sensing electrode provide a simple-yeteffective method to achieve a detection of ROS (H2O2-OH) with high sensitivity and efficiency. This innovation promises to revolutionize the field of wound inflammation treatment by providing clinicians with a powerful tool for accurate and rapid assessment of ROS levels, ultimately leading to improved patient outcomes. [ABSTRACT FROM AUTHOR]

This article is devoted to the study of the effect of ZnO nanoparticles on the development of tolerance to salt stress in rye samples. As a quantitative criterion for assessing the degree of oxidative stress, the amount of H2O2 released in the samples during growth was determined. For these purposes, an electrochemical sensor based on hydrothermally synthesized wall-shaped NiO nanostructures was developed. This sensor has been proven to demonstrate high sensitivity (2474 µA·mM−1), a low limit of detection (1.59 µM), good selectivity against common interferents, and excellent long-term stability. The investigation reveals that the incorporation of ZnO nanoparticles in irrigation water notably enhances rye's ability to combat salt stress, resulting in a decrease in detected H2O2 levels (up to 70%), coupled with beneficial effects on morphological traits and photosynthetic rates. [ABSTRACT FROM AUTHOR]

The use of hydrogen peroxide (produced in situ or ex situ) as the main agent in oxidative processes of environmental pollutant removal is widely studied. The degradation of water pollutants, such as dyes, pharmaceuticals, cosmetics, petroleum derivatives, and even pathogens, has been successfully obtained by different techniques. This review gives an overview of the more recent methods developed to apply oxidative processes mediated by H2O2 and other reactive oxygen species (ROS) in environmental catalysis, with particular attention to the strategies (Fenton-like and Bio-Fenton, photo- and electro-catalysis) and the materials employed. A wide discussion about the characteristics of the materials specifically studied for hydrogen peroxide activation, as well as about their chemical composition and morphology, was carried out. Moreover, recent interesting methods for the generation and use of hydrogen peroxide by enzymes were also presented and their efficiency and applicability compared with the Fenton and electro-Fenton methods discussed above. The use of Bio-Fenton and bi-enzymatic methods for the in situ generation of ROS seems to be attractive and scalable, although not yet applied in full-scale plants. A critical discussion about the feasibility, criticalities, and perspectives of all the methods considered completes this review. [ABSTRACT FROM AUTHOR]

The treatment of wound inflammation is intricately linked to the concentration of reactive oxygen species (ROS) in the wound microenvironment. Among these ROS, H2O2 serves as a critical signaling molecule and second messenger, necessitating the urgent need for its rapid real-time quantitative detection, as well as effective clearance, in the pursuit of effective wound inflammation treatment. Here, we exploited a sophisticated 3D Cu2-xSe/GO nanostructure-based nanonzymatic H2O2 electrochemical sensor, which is further decorated with evenly distributed Pt nanoparticles (Pt NPs) through electrodeposition. The obtained Cu2-xSe/GO@Pt/SPCE sensing electrode possesses a remarkable increase in specific surface derived from the three-dimensional surface constructed by GO nanosheets. Moreover, the localized surface plasma effect of the Cu2-xSe nanospheres enhances the separation of photogenerated electron-hole pairs between the interface of the Cu2-xSe NPs and the Pt NPs. This innovation enables near-infrared light-enhanced catalysis, significantly reducing the detection limit of the Cu2-xSe/GO@Pt/SPCE sensing electrode for H2O2 (from 1.45 μM to 0.53μM) under NIR light. Furthermore, this biosensor electrode enables in-situ real-time monitoring of H2O2 released by cells. The NIR-enhanced Cu2-xSe/GO@Pt/SPCE sensing electrode provide a simple-yet-effective method to achieve a detection of ROS (H2O2、-OH) with high sensitivity and efficiency. This innovation promises to revolutionize the field of wound inflammation treatment by providing clinicians with a powerful tool for accurate and rapid assessment of ROS levels, ultimately leading to improved patient outcomes.

Under heat-free conditions, three wheel-shaped [P8W48O184]40− ({P8W48})-based polyoxometalates (POMs) were controllably synthesized via the reaction of a hexavacant Dawson-type tungstophosphate, K12[H2P2W12O48]·24H2O (K-{P2W12}), with simple transition metal (TM) (TM = Mn, Co, and Ni) salts in room temperature aqueous solutions. The molecular formulas of the POMs were Na24[Mn8(H2O)32P8W48O184]·58H2O (1), K4Na16H4[Co8(H2O)32P8W48O184]·76H2O (2), and Na20H4[Ni8(H2O)32P8W48O184]·72H2O (3). It should be noted that eight TM ions introduced into each POM skeleton were connected in a {P8W48} wheel. To the best of our knowledge, this is the first time that the self-assembly of 3d-TM-{P8W48} with the internal coordination of all metals in an aqueous solution was achieved without heating. Compounds 1–3 were characterized by elemental, single-crystal X-ray diffraction, and other physical and spectral analyses, and their nonenzymatic electrochemical sensing performance for hydrogen peroxide (H2O2) was investigated by cyclic voltammetry. Compared with K28Li5[H7P8W48O184]·92H2O without 3d-TM and most reported POM electrode materials, the proposed 3d-TM-{P8W48} POMs exhibited higher stability and better activity during H2O2 detection. Composite films formed using 1–3 and chitosan (CS) on a glassy carbon electrode exhibited a high sensitivity (1.21 μA∙mmol∙L−1), low detection limit (0.02 mmol∙L−1), and rapid response time (2 s) for H2O2 detection. The study findings show that the combination of CS and 1–3 provides an alternative to soluble TM-{P8W48} compounds, which are not reusable in H2O2 detection systems.

Multifunctional materials based on carbon xerogel (CX) with embedded bismuth (Bi) and iron (Fe) nanoparticles are tested for ultrasensitive amperometric detection of lead cation (Pb2+) and hydrogen peroxide (H2O2). The prepared CXBiFe-T nanocomposites were annealed at different pyrolysis temperatures (T, between 600 and 1050 °C) and characterized by X-ray diffraction (XRD), Raman spectroscopy, N2 adsorption, dynamic light scattering (DLS), and electron microscopies (SEM/EDX and TEM). Electrochemical impedance spectroscopy (EIS) and square wave anodic stripping voltammetry (SWV) performed at glassy carbon (GC) electrodes modified with chitosan (Chi)-CXBiFe-T evidenced that GC/Chi-CXBiFe-1050 electrodes exhibit excellent analytical behavior for Pb2+ and H2O2 amperometric detection: high sensitivity for Pb2+ (9.2·105 µA/µM) and outstanding limits of detection (97 fM, signal-to-noise ratio 3) for Pb2+, and remarkable for H2O2 (2.51 µM). The notable improvements were found to be favored by the increase in pyrolysis temperature. Multi-scale parameters such as (i) graphitization, densification of carbon support, and oxide nanoparticle reduction and purification were considered key aspects in the correlation between material properties and electrochemical response, followed by other effects such as (ii) average nanoparticle and Voronoi domain dimensions and (iii) average CXBiFe-T aggregate dimension. [ABSTRACT FROM AUTHOR]

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The NiAlO@PPy-Ag sensing material was designed and prepared via in-situ oxidative polymerization of pyrrole monomer on the NiAl-oxide (NiAlO), and then anchoring Ag nanoparticles (NPs) on the surface of the NiAlO@PPy carrier. It was determined that the NiAlO particles were encased by PPy chains and Ag NPs were homogeneously distributed on the NiAlO@PPy based on various structural characterization. Subsequently, the NiAlO@PPy-Ag was directly fabricated into a non-enzymatic sensor for the detection of H2O2, which sensor showed a high sensitivity and selectivity toward H2O2 with a low detection limit of 0.03 μmol∙L−1 and high sensitivity of 346.50 μA∙mmol−1∙cm−2, and excellent repeatability and reproducibility. The results demonstrated that the NiAlO@PPy-Ag was a promising electrocatalytic material for H2O2 detection in the biological, clinical and environmental fields. [ABSTRACT FROM AUTHOR]

This study is focused on synthesizing environmentally friendly nano-probes for rapid and sensitive detection of H2O2. Biogenic manganese oxide nanoparticles were prepared and capped with two different types of nitrogen doped carbon dots. Nanocomposites are designated as NC1 (semicarbazide hydrochloride as a dopant source) and NC2 (urea as a dopant source). Synthesized nanocomposites (NC1 and NC2) were characterized by different techniques. UV-visible spectra depicted peaks at 298 nm (NC1) and 299 nm (NC2). FTIR confirmed the presence of different functional groups at the surface of nanocomposites. XRD showed the amorphous carbon structure of nanocomposites with particle size of 7 nm (NC1) and 6 nm (NC2). Raman spectra showed the graphitic carbon structure. In both cases, D and G bands were observed with ID/IG ratio equal to 0.76 for NC1 and 0.16 for NC2. NC1 depicted linearity for the concentration range of 10–40 µM with LOD and LOQ of 7 and 24 µM, respectively, while NC2 exhibited linearity over the concentration range of 50–80 µM with LOD of 12 µM and LOQ of 40 µM. Percentage recoveries for spiked samples were calculated to be 99.8–101.8 and 98.5–99.1% for NC1 and NC2, respectively. [ABSTRACT FROM AUTHOR]

This article is devoted to the study of the effect of ZnO nanoparticles on the development of tolerance to salt stress in rye samples. As a quantitative criterion for assessing the degree of oxidative stress, the amount of H2O2 released in the samples during growth was determined. For these purposes, an electrochemical sensor based on hydrothermally synthesized wall-shaped NiO nanostructures was developed. This sensor has been proven to demonstrate high sensitivity (2474 µA·mM−1), a low limit of detection (1.59 µM), good selectivity against common interferents, and excellent long-term stability. The investigation reveals that the incorporation of ZnO nanoparticles in irrigation water notably enhances rye’s ability to combat salt stress, resulting in a decrease in detected H2O2 levels (up to 70%), coupled with beneficial effects on morphological traits and photosynthetic rates.

We herein describe a novel lateral flow assay (LFA) to detect H 2 O 2 by utilizing self-biotinylation of G-quadruplex (G4). In this strategy, the G4 strand promotes the self-biotinylation of G4 itself in the presence of H 2 O 2 , which is then allowed to bind to the FAM-labeled complementary detector probe. The resulting biotin-labeled G4/FAM-detector probe complex is captured on the test line, producing a red-colored band during lateral flow readout. Based on this unique approach, we achieved the naked-eye detection of target H 2 O 2 at concentrations as low as 1 μM, with reliable quantification down to 0.388 μM. This method also demonstrated exceptional specificity in distinguishing H 2 O 2 from other non-target molecules. We further verified its versatile applicability by reliably identifying another biomolecule, choline, by coupling with choline oxidase, which generates H₂O₂ during oxidation. This novel LFA strategy holds great promise as a powerful point-of-care testing (POCT) platform for detecting a large spectrum of target biomolecules by employing their corresponding oxidases. [ABSTRACT FROM AUTHOR]

Photoacoustic (PA) imaging with much deeper tissue penetration and better spatial resolution had been widely employed for the prevention and diagnosis of many diseases. In this study, a new type of hydrogen peroxide (H2O 2) -activated photoacoustic nanoprobe [Mn-AH nanoscale coordination polymer nanodots (NCPs)] was successfully synthesized by a simple one-step method in water phase containing 2,2 ′ -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), horse radish peroxidase (HRP), and manganese ion (Mn 2 +). After modification by polyethylene glycol (PEG), Mn-AH NCPs exhibited excellent stability and biocompatibility for in vivo H2O2-responsive chromogenic assay with great specificity and sensitivity. In the presence of H2O2, colorless ABTS would be converted by HRP into the oxidized form with strong near-infrared (NIR) absorbance, enabling photoacoustic detection of endogenous H2O2. Using H2O2-activated Mn-AH NCPs, we have successfully performed PA imaging and H2O2 detection of subcutaneous murine colon CT26 tumor and deep-seated orthotopic bladder tumor. Due to the inherent Mn element existence inside the Mn-AH, this nanoprobe also serves as a good T1-weighted magnetic resonance imaging (MRI) contrast agent simultaneously. Lastly, after accomplishing its imaging functions, the Mn-AH NCPs could be cleared out from the body without any long-term toxicity, providing a new opportunity for cancer diagnosis and treatment. [ABSTRACT FROM AUTHOR]

Functionalized few-layer borophene (FFB) was prepared using gallnut extract and coffee waste extract as natural exfoliating and stabilizing agents in an environmentally friendly ultrasonic and high shear exfoliation. Here, a facile precipitation method was employed to grow iron oxide nanoparticles doped with cerium (Ce-FeONPs) onto the surface of FFB. This intriguing combination of materials yielded Ce-FeONPs nanoparticles that exhibited exceptional peroxidase-like activity, efficiently catalyzing the conversion of 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue oxidized TMB (oxTMB) in the presence of hydrogen peroxide (H 2 O 2). Additionally, the introduction of FFB contributes a reducibility effect to the catalytic oxidation of TMB, facilitating the restoration of the oxTMB to TMB. Thus, FFB-Ce-FeONPs showcase intriguing properties encompassing both oxidative and reductive characteristics, suggesting their potential as a reagent for repeated detection of H 2 O 2. Moreover, a colorimetric sensing system enabled the liner detection of H 2 O 2 spanning a concentration range from 0.08 to 1 mM, with a detection limit of 0.03 mM. Noteworthily, FFB-Ce-FeONPs demonstrated sustained efficacy over ten successive recycling cycles, as indicated by consistent slopes and observable color changes. In summary, this work reports the first application of nanoenzymes in repetitive H 2 O 2 detection. Even after ten multiple cycles, the detection limit remains virtually unaltered, underscoring the robustness and enduring effectiveness of the engineered nanomaterial. The proposed simultaneous oxidation and reduction strategies for detecting H 2 O 2 showed a commendable capability in ten cycles of H 2 O 2 detection, thus providing a promising approach in the field of H 2 O 2 detection. [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID-19) is a highly contagious illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), resulting in a global health crisis. The primary diagnostic method for COVID-19 is quantitative reverse transcription PCR, which is time-consuming and requires expensive instrumentation. Here, we developed an electrochemical biosensor for detecting SARS-CoV-2 biomarkers using a 3D porous polyacrylamide/polyaniline hydrogel (PPG) electrode prepared by UV photopolymerization and in situ polymerization. The electrochemical immunosensor for detecting SARS-CoV-2 N protein via the immune sandwich principle demonstrated a lower detection limit of 42 pg/mL and comparable specificity to a commercial enzyme-linked immunosorbent assay, which was additionally validated in pseudoviruses. The electrochemical sensor for hydrogen peroxide showed a low detection limit of 0.5 μM and excellent selectivity, which was further confirmed in cancer cells under oxidative stress. The biomarkers of SARS-CoV-2 were successfully detected due to the signal amplification capability provided by 3D porous electrodes and the high sensitivity of the antigen-antibody specific binding. This study introduces a novel three-dimensional electrode with great potential for the early detection of SARS-CoV-2. [ABSTRACT FROM AUTHOR]

We aimed to synthesize sensitive electrochemical sensors for hydrogen peroxide sensing by using zinc oxide nanorods grown on a fluorine-doped tin oxide electrode by using the facial hydrothermal method. It was essential to keep the surface morphology of the material (nanorods structure); due to its large surface area, the concerned material has enhanced detection ability toward the analyte. The work presents a non-enzymatic H2O2 sensor using vertically grown zinc oxide nanorods on the electrode (FTO) surfaces with Cu nanoparticles deposited on zinc oxide nanorods to enhance the activity. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-Ray (EDX), X-ray diffraction (XRD), and electrochemical methods were used to characterize copper–zinc oxide nanorods. In addition to the high surface area, the hexagonal Cu-ZnO nanorods exhibited enhanced electrochemical features of H2O2 oxidation. Nanorods made from Cu-ZnO exhibit highly efficient sensitivity of 3415 μAmM−1cm−2 low detection limits (LODs) of 0.16 μM and extremely wide linear ranges (0.001–11 mM). In addition, copper-zinc oxide nanorods demonstrated decent reproducibility, repeatability, stability, and selectivity after being used for H2O2 sensing in water samples with an RSD value of 3.83%. Cu nanoparticles decorated on ZnO nanorods demonstrate excellent potential for the detection of hydrogen peroxide, providing a new way to prepare hydrogen peroxide detecting devices.

Research into metal nanoparticles has increased, and they have been increasingly used in non-enzymatic sensor applications. However, there have been few reports on the use of natural products to prepare non-precious metal nanoparticles in an eco-friendly (green) manner. Studies were conducted on Cu nanoparticles (Cu NPs) prepared by the use of natural gallic acid (GA). This method is environmentally friendly and can be applied to H2O2 detection. As-obtained Cu NPs were characterized by x-ray photoelectron spectroscopy (XPS), powder x-ray diffraction (XRD), and transmission electron microscopy (TEM). When applied to H2O2 detection, Cu NPs had good sensitivity, stability, and anti-interference properties. Its electrochemical performance is no less than that of precious metal nanomaterials. Cu NPs mainly exhibit good sensitivity, reaching 5.74 μA mM-1 cm-2; the concentration range thereof is 1–20 mM. The process of constructing nanoparticles in this work used natural products, making it environmentally friendly and proving the practicality of constructing non-precious metal nanoparticles and the feasibility of their application to H2O2 detection. [ABSTRACT FROM AUTHOR]

Herein, an Au nanoparticles-polydopamine-poly acrylic acid-graphene (Au NPs-PDA-PAA-graphene) multicomponent nanohybrid is fabricated by surface functionalization of graphene alongside extensive in-situ growth of Au nanoparticles. The as-obtained nanocomposite possesses good hydrophilicity, excellent biocompatibility and high biomolecules loading capacity, which acts as an ideal platform for enzyme modification. Considering this fact, Horseradish peroxidase is expressively immobilized upon Au NPs-PDA-PAA-graphene surface, in order to lay the foundations of a biosensor that is majorly based on enzymatic activity. The biosensor exhibits higher sensitivity towards the determination of H2O2 with linearity ranging from 0.1 μm upto 20 mm, and the limit of detection going down to 0.02 μm. Encouraged by its acceptable electrocatalytic performance, this multicomponent system can also be easily employed for carrying out the real-time tracking of H2O2 coming out of Macrophage cells. Therefore, this work designs an extraordinarily updated platform for biosensing related applications, and also presents a reliable platform for the direct detection of H2O2in vivo and in vitro, which show great potential in bioelectroanalytical chemistry, cellular biology, and pathophysiology.

As an important detection technology, how to realize the rapid detection of H2O2 is very important for the early diagnosis of some diseases. Herein, octahedral porous carbon composites containing Cu and MoO2 are prepared by using bimetallic metal–organic frame (MOF) NENU-5 as precursor. It is found that Cu and MoO2 nanoparticles of Cu-MoO2-C are uniformly dispersed in the porous carbon framework. For the electrochemical detection of H2O2, compared with the Cu-C composite without MoO2, Cu-MoO2-C shows stronger redox ability, higher sensitivity (121 μA mM−1 cm−2), and lower detection limit (95.5 nM). In addition, Cu-MoO2-C also shows strong anti-interference ability and H2O2 detection sensitivity in the presence of a variety of interference substances. Our work proves that MoO2 has a good H2O2 reduction ability, and it also proves that the H2O2 detection performance of the sensors can be improved by using the constructed metal–metal oxide-porous frame materials. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H 2 O 2) is an environmentally friendly intermediate in the environmental field and also plays an important role in human metabolism, but the production and accumulation of excessive H 2 O 2 will cause harm to the human body, resulting in serious damage to cells. Therefore, N-doped graphene quantum dots Fe 3 O 4 /Co 3 O 4 nanoparticles with core-shell structure were prepared by in-situ synthesis and precipitation. The experimental results show that the prepared Co 3 O 4 nanoparticles have more efficient peroxidase activity than Co 3 O 4 nanoparticles alone. It can catalyze the oxidation of 3, 3, 5, 5-tetramethylbenzidine (TMB) to produce a blue product (TMBox) in the presence of H 2 O 2. In addition, Co 3 O 4 with negative charge in the shell can produce a strong electrostatic driving coordination effect with positively charged TMB, which enhances the affinity between the nanoparticles and the substrate, and selectively catalyzes H 2 O 2 oxidation of colorless TMB to turn it blue. Based on these experimental results, a simple, low-cost, and efficient colorimetric method for H 2 O 2 detection was established, which showed a sensitive response to H 2 O 2 in the range of 0.02–2.5 μM with a detection limit of 2.3 nM. In addition, due to the magnetic properties of the prepared nanoparticles, they could be easily recovered by applying a magnetic field. This research provides a viable approach for magnetic nanomaterials with encouraging prospects for environmental monitoring, biosensing, and more. [Display omitted] [ABSTRACT FROM AUTHOR]

• Bimetallic Mo 1-x W x S 2 identifies composition-dependent H 2 O 2 sensing associated with intermediate bindings. • The optimal Mo 0.75 W 0.25 S 2 accomplishes outstanding performance in H 2 O 2 sensing. • The Mo 0.75 W 0.25 S 2 distinguishes cancer cells via monitoring endogenous H 2 O 2. Two-dimensional transition-metal dichalcogenides can serve as emerging biosensing platforms after rational structural optimization. Herein, we develop a series of Mo 1-x W x S 2 and investigate the composition-dependent sensing of hydrogen peroxide (H 2 O 2). Among them, the Mo 0.75 W 0.25 S 2 affords high sensitivity (1290 μA mM−1 cm−2), good selectivity, and wide applicable concentration range (4 × 10−1–1.0 × 104 μM). As indicated by theoretical investigations, such prominent performance stems from the bimetallic electronic configurations and the enhanced *OH binding on surface. Moreover, the Mo 0.75 W 0.25 S 2 is capable of monitoring trace amounts of H 2 O 2 released from normal cells and various cancer cells, which provides efficient cell detection for clinical diagnosis. In addition, the composition-dependence, as a result of electronic modulation on Mo 1-x W x S 2 surface, is further evidenced on electrocatalytic hydrogen evolution reaction, which highlights the promise in sensing and electrocatalysis that share similar electrochemical fundamentals. [ABSTRACT FROM AUTHOR]

Flexible and portable film sensor (PLA@RPEG@TBSN) that embedded with AIE-featured nanoparticles is constructed for selective detection of gaseous H 2 O 2 using ratio fluorescence strategy. Moreover, effective photodynamic antimicrobial performance and multifunctional wearable applications can be realized for the film sensor. [Display omitted] • Flexible film sensor with H 2 O 2 detection and antibacterial characters is constructed. • Efficient fluorescence emission is ensured by the embedded AIE-active responder. • Sensitive H 2 O 2 vapor detection with visual color change is achieved by ratio method. • Photodynamic antimicrobial can be sufficiently realized by the film sensor. • Multifunctional wearable applications of the film sensor have been implemented. The development of portable flexible sensors for sensitive gas detection with antibacterial activity is of great significance for protecting human health and environment safety. In this paper, we designed a ratiometric sensing platform (PLA@RPEG@TBSN) for reliable and visual monitoring of gaseous H 2 O 2 by electrospinning technology, which reveals self-antibacterial function and highly photostability simultaneously. By employing the aggregation-induced emission (AIE) active nanoparticles (TBSN) as fluorescent responder and Rose Bengal modified photosensitive polymer (RPEG) as reference unit, accurate ratiometric sensing process of PLA@RPEG@TBSN film was realized based on the specific peroxide-mediated reaction between TBSN and H 2 O 2. The flexible film system demonstrated superior sensing performance toward H 2 O 2 vapor, including excellent selectivity, visualized color change and low detection limit (7 ppb). Additionally, benefitting from the photodynamic activity of RPEG, the PLA@RPEG@TBSN film exhibited highly effective antibacterial performance (killing 84 % of bacteria). Moreover, the multifunctional wearable potential is supported by employing film sensor onto the protective mask, which reveals dual capabilities of ratio sensing and resistance bacteria aerosols, encouraging the application of the sensor in complex practical scenario. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks with diverse structures and unique properties have demonstrated that can be an ideal substitute for natural enzymes in colorimetric sensing platform for analyte detection in various fields such as environmental chemistry, biotechnology and clinical diagnostics, which have attracted the scientist's attention, recently. In this study, a porous coordination network (denoted as PCN-222) was synthesized as a new biomimetic material from an iron linked tetrakis (4-carboxyphenyl) porphyrin (named as Fe-TCPP) as a heme-like ligand and Zr6 linker as a node. This catalyst shows the peroxidase and catalase activities clearly. The mechanism of peroxidase activity for PCN-222 was investigated using the spectrophotometric methods and its activity was compared with the other nanoparticles which, the results showed a higher activity than the other catalysts. Also, the hydrogen peroxide was detected by PCN-222(Fe) based on the peroxidase-like activity. For detection of hydrogen peroxide a linear range of 3–200 µM and detection of limit (LOD) 1 µM (3σ/slope), under optimal conditions were obtained. Moreover, based on the high tendency of PCN-222(Fe) to combine with the TMB as a chromogenic substrate in the peroxidase-like activity, we developed the sensitive and selective colorimetric assay for glucose detection that was found a detection limit (LOD) of 2.2 µM in the linear range from 12 to 75 µM. Finally due to the good catalytic activity of PCN-222(Fe), it was used to detection of glucose and hydrogen peroxide in real samples. [ABSTRACT FROM AUTHOR]

The mechanism behind the variation in the photoluminescence (PL) of a MoS2 nanohybrid material with pH was investigated. Highly fluorescent MoS2 quantum dots dispersed across MoS2 nanosheets (MoS2 QDNS) were synthesized by a hydrothermal route in the presence of NaOH. Upon reducing the pH from 13 to 6.5, the PL intensity was markedly quenched. The removal of dangling sulfur atoms by adding mineral acids could be a plausible mechanism for this PL quenching, together with the inner filter effect and Förster resonance energy transfer due to the resulting species. A label-free turn-on fluorescence sensor for H2O2 was developed using this hybrid material. The PL of the acidified MoS2 QDNS at pH 6.5 increased (i.e., recovered) linearly with the concentration of H2O2. The dynamic range of the sensor was found to be 2–94 μM with a limit of detection (LOD) of 2 μM. This sensing strategy was also extended for the detection of glucose by appending glucose oxidase (GOx) as a catalyst. In the presence of GOx, glucose oxidizes to gluconic acid and H2O2, so the original level of glucose can be estimated by determining the H2O2 present. The absence of a complicated enzyme immobilization step is the prime advantage of the present glucose sensor. The current work exemplifies the utility of MoS2-based nanoparticle systems in the biological sensor domain. [ABSTRACT FROM AUTHOR]

The mechanism behind the variation in the photoluminescence (PL) of a MoS2 nanohybrid material with pH was investigated. Highly fluorescent MoS2 quantum dots dispersed across MoS2 nanosheets (MoS2 QDNS) were synthesized by a hydrothermal route in the presence of NaOH. Upon reducing the pH from 13 to 6.5, the PL intensity was markedly quenched. The removal of dangling sulfur atoms by adding mineral acids could be a plausible mechanism for this PL quenching, together with the inner filter effect and Förster resonance energy transfer due to the resulting species. A label-free turn-on fluorescence sensor for H2O2 was developed using this hybrid material. The PL of the acidified MoS2 QDNS at pH 6.5 increased (i.e., recovered) linearly with the concentration of H2O2. The dynamic range of the sensor was found to be 2–94 μM with a limit of detection (LOD) of 2 μM. This sensing strategy was also extended for the detection of glucose by appending glucose oxidase (GOx) as a catalyst. In the presence of GOx, glucose oxidizes to gluconic acid and H2O2, so the original level of glucose can be estimated by determining the H2O2 present. The absence of a complicated enzyme immobilization step is the prime advantage of the present glucose sensor. The current work exemplifies the utility of MoS2-based nanoparticle systems in the biological sensor domain. [ABSTRACT FROM AUTHOR]

Abstract Introducing Pt-based bimetallic nanocrystals into biosensors as a modifying agent has aroused immense interests to develop advanced non-enzymatic sensors for detecting H 2 O 2. In this study, Pt-Cu alloy octahedra with controlled compositions are prepared through a facile method serving as a modifying agent in biosensors for H 2 O 2 detection. The formation of Pt-Cu octahedra is achieved by simultaneous reduction of H 2 PtCl 6 and CuCl 2 by using N, N-dimethylformamide without addition of any other capping agents. A key to the synthesis of Pt-Cu octahedra is the introduction of Cl− ions, which can act as a dynamic template to facilitate the preferential overgrowth and accelerate the overall reduction kinetics. Compare to commercial Pt/C and spherical Pt-Cu nanoparticles, the Pt-Cu octahedra modified biosensors show substantially enhanced activity towards H 2 O 2 detection due to the unique synergetic effect between Pt and Cu and surface structure. Specifically, the electrode modified by Pt 55 Cu 45 octahedra achieves the highest sensitivity and best selectivity in neutral solution with a detection limit of 0.17 μM. Highlights • Pt-Cu alloy octahedra were synthesized by introduction of Cl− ions as a dynamic template. • Pt-Cu alloy octahedra showed high catalytic activity and good reliability for H 2 O 2 detection. • Synergetic effect and unique surface structure were two main reasons for enhancing the H 2 O 2 detection activity. [ABSTRACT FROM AUTHOR]

Herein, a mesoporous silica nanoparticle (MSN) based ratiometric fluorescence nanosensor (MSN-BA-SiCD) with improved performance was designed for monitoring hydrogen peroxide (H 2 O 2). Specifically, H 2 O 2 response molecule (BA) with AIE feature was synthesized and encapsulated into MSN channel as the fluoresent recognition site. Afterwards, silane-modified carbon dot (SiCD) was covalently connected to the MSN surface which can effectively prevent the leakage of BA and improve the water dispersibility of the nanosensor. The presence of H 2 O 2 could result in a "turn-on" fluorescence of BA as well as concurrent variation in the fluorescence resonance energy transfer (FRET) signal between SiCD and BA. MSN-BA-SiCD displays a specific blue-to-green resolved emission change in response to H 2 O 2 and the detection limit can be as low as 4.78 × 10−6 M. In addition, the nanosensor exhibited enhanced photostability due to the protection of the material framework. Moreover, the nanosensing system was successfully applied to detect H 2 O 2 in beer, orange juice and living cells. The excellent water dispersibility and photostability of the nanosensor, together with high specificity and biocompatibility, constituted an advanced set of characteristics among existing MSNs, which was expected to further promote the development of H 2 O 2 sensors in the environmental and biological fields. [Display omitted] • A ratio fluorescence nanosensor is designed based on carbon dot modified MSN. • Selective and sensitive detection of H 2 O 2 is achieved by FRET based ratio sensing. • Improved water dispersibility and photostability are exhibited for the nanosensor. • The nanosensor is successfully applied in drink samples and cell imaging. [ABSTRACT FROM AUTHOR]

A super-porous hybrid platform can offer significantly increased number of reaction sites for the analytes and thus can offer advantages in the biosensor applications. In this work, a significantly improved sensitivity and selectivity of hydrogen peroxide (H2O2) detection is demonstrated by a super-porous hybrid CuO/Pt nanoparticle (NP) platform on Si substrate as the first demonstration. The super-porous hybrid platform is fabricated by a physiochemical approach combining the physical vapor deposition of Pt NPs and electrochemical deposition of super-porous CuO structures by adopting a dynamic hydrogen bubble technique. Under an optimized condition, the hybrid CuO/Pt biosensor demonstrates a very high sensitivity of 2205 µA/mM·cm2 and a low limit of detection (LOD) of 140 nM with a wide detection range of H2O2. This is meaningfully improved performance as compared to the previously reported CuO-based H2O2 sensors as well as to the other metal oxide-based H2O2 sensors. The hybrid CuO/Pt platform exhibits an excellent selectivity against other interfering molecules such as glucose, fructose, dopamine, sodium chloride and ascorbic acid. Due to the synergetic effect of highly porous CuO structures and underlying Pt NPs, the CuO/Pt architecture offers extremely abundant active sites for the H2O2 reduction and electron transfer pathways.

Three-dimensional (3D) layer-by-layer graphene-gold nanorod (GNR) architecture has been constructed. The resulting hybrid nanomaterials’ architecture has been tested for detecting hydrogen peroxide (H2O2) through the electrocatalytic reaction on a three electrode disposable biosensor platform. Cyclic voltammetry and amperometry were used to characterize and assess the performance of the biosensor. The 3D layer-by-layer modified electrode exhibited the highest sensitivity compared to the active carbon, graphene-oxide, cysteine-graphene oxide and GNR coated electrodes. This research explored the feasibility of using the 3D hybrid graphene-GNR as a template for biosensor. The 3D hybrid structure exhibited higher sensitivity than GNRs alone. SEM showed the explanation that GNRs had self-aggregates reducing the contact surface area when coated on the active carbon electrode, while there were no such aggregates in the 3D structure, and TEM illustrated that GNRs dispersed well in the 3D structure. This research demonstrated a better way to prepare well-separated metal nanoparticles by using the 3D layer-by-layer structure. Consequently, other single and bi-metallic metal nanoparticles could be incorporated into such structure. As a practical example, 3D layer-by-layer nanomaterials modified active carbon electrode was used for detecting glucose showing very good sensitivity and minimum interference by ascorbic acid and uric acid in test solution, which indicated a good selectivity of the biosensor as well.

Abstract In this work, we report a novel sensor for colorimetric and fluorometric H 2 O 2 sensing which is based on silver nanoparticles decorated and tetraphenylethene probe doped silica nanoparticles (Ag@TPE-SiO 2 NPs). A positively charged tetraphenylethene (TPE) probe is doped into silica nanoparticles, and the nanoparticles exhibit strong fluorescence emission due to aggregation-induced emission (AIE) of the TPE probe. Ag nanoparticles (AgNPs) are prepared in situ on the surface of the silica nanoparticles. AgNPs serve as a nanoquencher which can quench the AIE emission of the TPE-SiO 2 NPs efficiently. However, AgNPs can be oxidized to Ag+ by H 2 O 2 , which leads to fluorescence recovery and color fading of the Ag@TPE-SiO 2 NPs. The dual-readout strategy allows sensitive analysis of H 2 O 2. The detection limit of the fluorometric and colorimetric assay is 0.28 and 2.1 μM, respectively. And the nanosensor also shows good selectivity. In addition, analysis of H 2 O 2 in human serum and intracellular imaging of H 2 O 2 are both demonstrated. With the good analytical properties of merit, the proposed nanoprobe has a promising potential for H 2 O 2 related bioanalysis and biomedical applications. Graphical abstract fx1 Highlights • A sensor based on AgNPs decorated and TPE probe doped silica NPs was fabricated. • This dual-mode colorimetric and fluorometric sensor was employed for H 2 O 2 sensing. • The determination of H 2 O 2 in human serum was demonstrated. • The nanosensor was successfully employed for intracellular imaging of H 2 O 2. [ABSTRACT FROM AUTHOR]

Precise designs of low-cost and efficient catalysts for the detection of hydrogen peroxide (H2O2) over wide ranges of pH are important in various environmental applications. Herein, a versatile and ecofriendly approach is presented for the rational design of ternary bentonite-silylpropyl-polypyrrole/silver nanoarchitectures (denoted as BP-PS-PPy/Ag) via the in-situ photo polymerization of pyrrole with salinized bentonite (BP-PS) in the presence of silver nitrate. The Pyrrolyl-functionalized silane (PS) is used as a coupling agent for tailoring the formation of highly exfoliated BP-PS-PPy sheet-like nanostructures ornamented with monodispersed Ag nanoparticles (NPs). Taking advantage of the combination between the unique physicochemical properties of BP-PS-PPy and the outstanding catalytic merits of Ag nanoparticles (NPs), the as-synthesized BP-PS-PPy/Ag shows a superior electrocatalytic reduction and high-detection activity towards H2O2 under different pH conditions (from 3 to 10). Intriguingly, the UV-light irradiation significantly enhances the electroreduction activity of H2O2 substantially, compared with the dark conditions, due to the high photoelectric response properties of Ag NPs. Moreover, BP-PS-PPy/Ag achived a quick current response with a detection limit at 1 μM within only 1 s. Our present approach is green, facile, scalable and renewable.

This work presents the modelling of impulsional pH variations in microvolume related to water-based electrolysis and hydrogen peroxide electrochemical oxidation using an Electrochemical Field Effect Transistor (ElecFET) microdevice. This ElecFET device consists of a pH-Chemical FET (pH-ChemFET) with an integrated microelectrode around the dielectric gate area in order to trigger electrochemical reactions. Combining oxidation/reduction reactions on the microelectrode, water self-ionization and diffusion properties of associated chemical species, the model shows that the sensor response depends on the main influential parameters such as: (i) polarization parameters on the microelectrode, i.e., voltage (Vp) and time (tp); (ii) distance between the gate sensitive area and the microelectrode (d); and (iii) hydrogen peroxide concentration ([H2O2]). The model developed can predict the ElecFET response behaviour and creates new opportunities for H2O2-based enzymatic detection of biomolecules.

The nanomaterials-based artificial enzymes have attracted great attention because of their high stability, good biocompatibility, high catalytic efficiency, and low cost in recent years. Herein, we synthesized a new covalent organic framework (COFs) through the dehydration reaction of 2,5-dihydroxyterephthalaldehyde and tetra-(4-aminophenyl) porphyrin, which was then used to fabricate the core-shell structured nanospheres (Fe 3 O 4 @COFs) by decorating on magnetic Fe 3 O 4. In the presence of hydrogen peroxide (H 2 O 2), the Fe 3 O 4 @COFs nanospheres were able to catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue product (ox-TMB), indicating their high peroxidase-like activity. Based on this phenomenon, the Fe 3 O 4 @COFs was used as a colorimetric probe for sensitive and selective detection of H 2 O 2 and glucose. The detection limit (LOD) of H 2 O 2 was calculated to be 2.6 μM in a linear range from 0.1 to 4 mM, while the LOD of glucose was valued as 6 μM ranging from 0.05 to 0.9 mM. Finally, this method was applied in the determination of the glucose concentration in human serum with high accuracy. Thus, the as-prepared Fe 3 O 4 @COFs could be used as a highly sensitive and selective peroxidase mimic to detect hydrogen peroxide-related molecules, suggesting their great potential in biomedical application. [Display omitted] • A new core-shell structured Fe 3 O 4 @COFs nanospheres was prepared and characterized. • Fe 3 O 4 @COFs displayed higher peroxidase activity than that of bare Fe 3 O 4. • Fe 3 O 4 @COFs was applied to analyze H 2 O 2 and glucose with high selectively. [ABSTRACT FROM AUTHOR]

Lignin is the second largest naturally renewable resource and is primarily a by-product of the pulp and paper industry; however, its inefficient use presents a challenge. In this work, Fe3O4 nanoparticles loaded on lignin nanoparticles (Fe3O4@LNPs) were prepared by the self-assembly method and it possessed an enhanced peroxidase-like activity. Fe3O4@LNPs catalyzed the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2 to generate a blue color, was observable by the naked eye. Under the optimal conditions, Fe3O4@LNPs showed the ability of sensitive colorimetric detection of H2O2within a range of 5⁻100 μM and the limit of detection was 2 μM. The high catalytic activity of Fe3O4@LNPs allows its prospective use in a wide variety of applications, including clinical diagnosis, food safety, and environmental monitoring.

Acylated xylan-based magnetic Fe3O4 nanocomposite hydrogels (ACX-MNP-gels) were prepared by fabricating Fe3O4 nanoctahedra in situ within a hydrogel matrix which was synthesized by the copolymerization of acylated xylan (ACX) with acrylamide and N-isopropylacrylamide under ultraviolet irradiation. The size of the Fe3O4 fabricated within the hydrogel matrix could be adjusted through controlling the crosslinking concentrations (C). The magnetic hydrogels showed desirable magnetic and mechanical properties, which were confirmed by XRD, Raman spectroscopy, physical property measurement system, SEM, TGA, and compression test. Moreover, the catalytic performance of the magnetic hydrogels was explored. The magnetic hydrogels (C = 7.5 wt %) presented excellent catalytic activity and provided a sensitive response to H2O2 detection even at a concentration level of 5 x 10-6 mol⋅L-1. This approach to preparing magnetic hydrogels loaded with Fe3O4 nanoparticles endows xylan-based hydrogels with new promising applications in biotechnology and environmental chemistry. [ABSTRACT FROM AUTHOR]

Highly sensitive, selective, and stable hydrogen peroxide (H2O2) detection using nanozyme-based catalysts are desirable for practical applications. Herein, vertical α-FeOOH nanowires were successfully grown on the surface of carbon fiber paper (CFP) via a low-temperature hydrothermal procedure. The formation of vertical α-FeOOH nanowires is ascribed to the structure-directing role of sodium dodecyl sulfate. The resulting free-standing electrode with one-dimensional (1D) nanowires offers oriented channels for fast charge transfer, excellent electrical contact between the electrocatalyst and the current collector, and good mechanical stability and reproducibility. Thus, it can serve as an efficient electrocatalyst for the reduction and sensitive detection of H2O2. The relation of the oxidation current of H2O2 with the concentration is linear from 0.05 to 0.5 mM with a sensitivity of -0.194 mA/(mM·Lcm2) and a low detection limit of 18 μM. Furthermore, the portability in the geometric tailor and easy device fabrication allow extending the general applicability of this free-standing electrode to chemical and biological sensors. [ABSTRACT FROM AUTHOR]

• Auto-redox process-engaged strategy (APES) is developed to anchor Au NPs on PC. • The driving force is the positive △ E between reduction potentials of AuCl 4 − and PC. • APES enables the formation of smaller Au NPs with high dispersion on PC surface. • APES-Au/PC is a multiple electrocatalyst for efficient H 2 O 2 -related applications. Carbon supported Au nanoparticles (NPs) with multifunctional electrocatalytic performances have captured broad interest, whereas their facile, green and efficient synthesis remains a formidable challenge. We report herein the utilization of low-cost, easy-to-prepare and efficient porous carbon (PC) with nanosheet morphology to in situ anchoring of ligand-free Au NPs via an auto-redox process-engaged strategy (APES) without involving any reductant, surfactant or organic solvent. The thermodynamically spontaneous nature for APES is ascribed to the positive △ E (1.232 V) between the reduction potential of AuCl 4 − and the oxidation potential of PC. Note that the APES enables the formation of smaller Au NPs with high dispersion on the PC surface compared with the impregnation-reduction method, which can provide an abundance of catalytically active sites for reaction. The achieved APES-Au/PC exhibits a significant activity for 2e− oxygen reduction reaction toward H 2 O 2 production with a concentration of 6.44 mM and H 2 O 2 selectivity of 95% in 0.1 M KOH. The in situ formed H 2 O 2 on APES-Au/PC electrode can be directly applied for Rhodamine B removal with a 98.7% degradation efficiency and high reusability. In addition, the APES-Au/PC electrode can be utilized to detect trace amount of H 2 O 2 in 0.1 M PBS with a high sensitivity of 119.7 µA mM−1 cm−2, low detection limit of 1.044 µM, and wide detection range of 0.001–20 mM. This study offers a carbon nanosheet-derived APES to efficiently fabricate supported Au NPs toward versatile applications, which matches well with the principles of green and sustainable chemistry. [ABSTRACT FROM AUTHOR]

Abstract: Tungsten carbide nanorods (WC NRs) are demonstrated for the first time to possess intrinsic peroxidase-like activity towards typical peroxidase substrates, such as 3, 3', 5, 5'-tetramethylbenzidine (TMB) and ο-phenylenediamine (OPD) in the presence of hydrogen peroxide (H2O2). The reactions catalyzed by these nanorods follow the Michaelis–Menten kinetics. The excellent catalytic performance of WC NRs could be attributed to their intrinsic catalytic activity to efficiently accelerate the electron-transfer process and facilitate the decomposition of H2O2 to generate more numbers of reactive oxygen species (ROS). Based upon the strong peroxidase-like activity of these WC NRs, a colorimetric sensor for H2O2 is designed, which provides good response towards H2O2 concentration over a range of 2×10−7–8×10−5 M with a detection limit of 60nM. Moreover, the peroxidase-like activities of WC NRs with TMB as the substrate are investigated in both protic and aprotic organic media, showing different colorimetric reactions from that performed in aqueous solutions. In comparison with the natural horse radish peroxidase, WC NR exhibits excellent robustness of catalytic activity and considerable reusability, thus making it a promising mimic of peroxidase catalysts. [Copyright &y& Elsevier]

The large surface, the excellent dispersion and the high degrees of sensitivity of bimetallic nanocatalysts were the attractive features of this investigation. Graphene foam (GF) was a three dimensional (3D) porous architecture consisting of extremely large surface and high conductive pathways. In this study, 3D GF was used incorporating platinum–ruthenium (PtRu) bimetallic nanoparticles as an electrochemical nanocatalyst for the detection of hydrogen peroxide (H2O2). PtRu/3D GF nanocatalyst exhibited a remarkable performance toward electrochemical oxidation of H2O2 without any additional mediator showing a high sensitivity (1023.1µAmM−1 cm−2) and a low detection limit (0.04µM) for H2O2. Amperometric results demonstrated that GF provided a promising platform for the development of electrochemical sensors in biosensing and PtRu/3D GF nanocatalyst possessed the excellent catalytic activity toward the H2O2 detection. A small particle size and a high degree of the dispersion in obtaining of large active surface area were important for the nanocatalyst for the best H2O2 detection in biosensing. Moreover, potential interference by ascorbic acid and uric acid appeared to be negligible. [ABSTRACT FROM AUTHOR]

Abstract: Here we report the derivatization of mesoporous TiO2 thin films for the preparation of H2O2 amperometric sensors. The coordination of the bifunctional ligand 1,10 phenantroline, 5,6 dione on the surface Ti(IV) ions provides open coordination sites for Fe(II) cations which are the starting point for the growth of a layer of Prussian blue polymer. The porous structure of the mesoporous TiO2 allows the growth, ion by ion of the coordination polymer. Up to four layer of Prussian blue can be deposit without losing the porous structure of the film, which results in an enhanced response of these materials as H2O2 sensors. These porous confined PB modified electrodes are robust sensors that exhibit good reproducibility, environmental stability and high sensitivity towards H2O2 detection. [ABSTRACT FROM AUTHOR]

Abstract: Biosensor performance depends on the effective functionalisation of a transducer with suitable biorecognition elements. During functionalisation, surface blocking steps are normally carried out to avoid later binding of undesirable molecules and thus guarantee biosensor specificity. However, these blocking steps may be deleterious in electrochemical systems where transduction ultimately relies on electron transfer between the electrode and a redox species in solution. This work presents a novel approach to develop improved amperometric biosensing platforms using microfabricated disk microelectrode arrays, based on the functionalisation of the inert surface surrounding the active microdisks. These devices more than doubled assay sensitivity compared to conventional biosensors produced using the same arrays. This approach benefits from three advantages: the functionalisation of a broader surface, the possibility to activate the microelectrodes immediately before detection, and access to enhanced rates of mass transport to microelectrodes that improve device sensitivity. To demonstrate this, we first studied the electrochemical behaviour of tetramethylbenzidine (TMB) at gold disk microelectrode arrays, and then used TMB as the redox mediator for the amperometric biosensing of HRP/H2O2. Down to 0.54pM H2O2 or as little as 25pM HRP were detected within 5s of enzyme activity in just 10μl of enzyme substrate solution. We postulate that microelectrode arrays may be used to develop novel electrochemical biosensing platforms that are faster and more sensitive than conventional biosensors. [Copyright &y& Elsevier]

• Templated formation of 3D ordered macroporous Au structure. • Electrodeposition of Cu 2 O thin film on Au inverse opaline skeletons. • Cu 2 O/Au inverse opals demonstrates enhanced H 2 O 2 sensing ability. • Synergy effect from structure and sensing mechanism. Composite Cu 2 O/Au inverse opals are fabricated by pulse electrodeposition of Cu 2 O on the skeletons of Au inverse opals, and their H 2 O 2 sensing performances are investigated in a phosphate buffered saline solution. In our composite structure, the Cu 2 O is responsible for H 2 O 2 sensing, and the Au inverse opals not only contribute to H 2 O 2 sensing but also serve as a current collector providing a large accessible area with interconnected pore channels for facile mass transport. The sensing mechanism of Cu 2 O and Au complement each other so their simultaneous exposure to H 2 O 2 leads to a larger sensing response. The composite Cu 2 O/Au inverse opals display a wide linear detection range (5–11,000 µM) and low detection limit (5 µM), as well as a two-stage sensitivity of 304.8 and 60.8 μA/(mM·cm2). In addition, they reveal a relatively low sensing potential (−0.1 V) as compared to alternative nanostructured counterparts. The selectivity and durability of composite Cu 2 O/Au inverse opals are also validated. The composite Cu 2 O/Au inverse opals are readily detached from the ITO substrate, rendering a free-standing sample that could accommodate designs for both in-vivo and in-vitro testing. [ABSTRACT FROM AUTHOR]