Colorimetric Detection Of H2O2 Research Articles

Ultrasensitive detection of H2O2 via electrochemical sensor by graphene synergized with MOF-on-MOF nanozymes.

An electrochemical sensor was developed for the detection of hydrogen peroxide (H2O2),utilizing the synergistic effects of graphene (Gr) and MOF-on-MOF nanozymes (FeCu-NZs). Initially, Fe-MOF with peroxide-like activity is synthesized using a solvothermal method. Subsequently, the organic ligand on its surface binds Cu2+, enhancing the enzyme-like activity further. The resulting FeCu-NZs exhibit a distinctive electrochemical signal in response to H2O2. Moreover, integrating FeCu-NZs with Gr significantly amplifies the electrochemical signal and effectively reduces the sensor's detection limit. The developed sensor exhibited linear ranges of 0.1-3800 μM, with a limit of detection (LOD) of 0.06 μM. Additionally, FeCu-NZs catalyze H2O2 to generate abundant •OH radicals, and colorimetric detection of H2O2 is facilitated using the color rendering principle of 3,3',5,5'-tetramethylbenzidine (TMB). Notably, this detection method was applied to determine H2O2 concentrations in real samples, achieving a recovery exceeding 95.7%. In summary, this research provides a practical platform for the construction of traditional nanozymes and the integration of electrochemical systems, which have broad applications in food analysis, environmental monitoring, and medical diagnosis.

Galvanic replacement synthesis of PtPdAu hollow nanorods as peroxidase mimic with high specific activity for colorimetric detection.

Noble metal nanomaterials have been widely demonstrated to possess intrinsic enzyme-like properties and have been increasingly applied in the fields of analysis and biomedicine. However, current exploration of high-activity noble metal nanozymes is still far from adequate. The construction of hollow structures and adjustment of their elemental composition are effective ways to improve the specific activity (SA) of nanozymes. In this study, trimetallic PtPdAu hollow nanorods (HNRs) were developed using a galvanic replacement reaction and Kirkendall effect. The catalytic experiment showed that the PtPdAu HNRs possessed outstanding peroxidase-like performance and their SA value was up to 563.71 U mg-1, which is remarkable among various previously reported nanozymes and higher than that of monometallic or bimetallic counterparts with similar structure and size prepared in this study. Electron paramagnetic resonance (EPR)measurements showed that the PtPdAu HNRs could contribute to the formation of hydroxyl radicals (˙OH) in catalyzing hydrogen peroxide. When using PtPdAu HNRs as a nanozyme in the colorimetric detection of H2O2 and ascorbic acid (AA), the limits of detection were as low as 1.8 μM and 0.068 μM, respectively. This study demonstrates that PtPdAu HNRs are high-activity nanozymes and have the potential to be applied in the field of analysis.

Polydopamine on Copper-Doped Cerium Dioxide Nanosheets as Peroxidase Mimics for the Intelligent Detection of Cholesterol.

The catalytic ability of nanozymes has become an enzymology hotspot in the field of application. Most nanozymes were characterized to simultaneously have oxidase-like and peroxidase-like activities, but the practical application often focuses on certain activity; other complex activities may cause interference. The peroxidase-like activity (POD-like activity) of nanozymes have been widely used in the colorimetric detection of H2O2 or substances producing H2O2 as an intermediate, such as the detection of small biological molecules with the oxidative reaction of a chromogenic reagent in the presence of POD-like nanozymes. In this work, we used polydopamine (PDA) as the surface coating of Cu-CeO2 nanosheets (PDA@ Cu-CeO2), which enhanced peroxidase-like activity while inhibiting their oxidase-like activity, providing a feasible method for the sensitive determination of cholesterol by integrating visual colorimetric detection and a smartphone application as a readout. The absorbance intensity and RGB values displayed a linear range on cholesterol from 0.05 to 1.2 mM with the LOD (limit of detection) of 42.7 and 99.4 μM. In addition, the method is expected to apply in detecting cholesterol in human serum with acceptable accuracy.

Palladium Nanoparticles Grafted onto Phytochemical Functionalized Biochar: A Sustainable Nanozyme for Colorimetric Sensing of Glucose and Glutathione.

The devising and development of numerous enzyme mimics, particularly nanoparticles and nanomaterials (nanozymes), have been sparked by the inherent limitations imposed by natural enzymes. Peroxidase is one of the enzymes that is extensively utilized in commercial, medical, and biological applications because of its outstanding substrate selectivity. Herein, we present palladium nanoparticles grafted on Artocarpus heterophyllus (jackfruit) seed-derived biochar (BC-AHE@Pd) as a novel nanozyme to imitate peroxidase activity en route to the rapid and colorimetric detection of H2O2, exploiting o-phenylenediamine as a peroxidase substrate. The biogenically generated BC-AHE@Pd nanocatalyst was synthesized utilizing Artocarpus heterophyllus seed extract as the reducing agent for nanoparticle formation, while the residue became the source for biochar. Various analytical techniques like FT-IR, GC-MS, FE-SEM, EDS, TEM, SAED pattern, p-XRD, and ICP-OES, were used to characterize the BC-AHE@Pd nanocatalyst. The intrinsic peroxidase-like activity of the BC-AHE@Pd nanocatalyst was extended as a prospective nanosensor for the estimation of the biomolecules glucose and glutathione. Moreover, the BC-AHE@Pd nanocatalyst showed recyclability up to three recycles without any significant loss in activity.

Insight into peroxidase and polyphenol oxidase mimic activity of spinel ferrite nanoparticles and their GO composites

Present work reports the comparative evaluation of MFe2O4 (M = Mn, Co and Cu) nanoparticles (NPs), graphene oxide (GO) and their nanocomposite (NC) for their intrinsic peroxidase and polyphenol oxidase (PPO) mimic activity of followed by the catalytic sensing of H2O2. Pure and doped MFe2O4 NPs were screened initially for peroxidase and PPO mimic activity. Among the tested metal ferrite NPs, MnFe2O4 NPs showed the highest enzyme mimic activity for both the enzymes. Thus, MnFe2O4-GO NC was synthesized by the facile ultrasonication method and characterized using FT-IR and XRD techniques. TEM micrographs of NC showed that MnFe2O4 NPs were anchored on GO sheets with lesser agglomeration than bare ferrite NPs. SEM-EDX confirmed the presence of MnFe2O4 and GO in NC. The greater surface area of NC as compared to pristine NPs was confirmed from BET analysis. MnFe2O4 NPs displayed highest peroxidase and PPO mimic activity followed by NC and GO. The results were correlated with the facile inter-conversion of Mn2+-Mn3+ ions. Thus, ease of inter-conversion of oxidation state was the dominating factor of highest activity of MnFe2O4 NPs rather than the surface area. The colorimetric detection of H2O2 was also achieved in the range 0.2 mM–1.0 mM H2O2. In-situ trapping experiments confirmed that OH. radicals were major active species involved in peroxidase mimic activity. The reaction mechanisms for both the reactions were proposed. Kinetic studies were performed and data was analysed using Michaelis Menten equation. The values of Vmax and Km for both the reactions proved MnFe2O4 NPs as potential oxidase mimic for a wide range of potential applications.

Colorimetric detection of hydrogen peroxide with gadolinium complex of phenylboronic acid functionalized 4,5-diazafluorene

Hydrogen peroxide (H2O2) is a member of reactive oxygen species (ROS) and has substantial physiological roles in living organisms. Currently, advanced techniques facilitate imaging of living systems with gadolinium based contrast agents and intense oxidation regions may be detected with convenient molecular design. Therefore, gadolinium complex of phenylboronic acid functionalized 4,5-diazafluorene (Gd-SCL) was designed for quantitative and colorimetric detection of H2O2. UV–vis, FTIR, 1H NMR, HPLC and ESI-MS methods were used in the characterizations. Conversion of phenylboronic unit to the phenol due to reaction with H2O2 was occurred in 35 min under alkaline aqueous medium with the color change from orange-yellow to transparent colorless and proved by mass analyses. Designed sensor exhibited a good response to H2O2 in the range of 0.5–500 µM with 0.41 μM limit of detection (LOD) in the prepared standard samples. The sensor showed an excellent selectivity for H2O2 in presence of interfering species and the optimum pH range for operation of the sensor was determined in the range of 7–12. Cosmetic product (hair bleach) with 9% peroxide content was used in real sample analyses and LOD was found as 3.83 nM. Considering the magnetic capability of Gd lanthanide, successful H2O2 detection with phenylboronic acid and presuming this research as pre-trial, Gd-SCL complex may be a candidate for magnetic resonance imaging (MRI) agent after further investigations.

Ionic liquid functionalized nano-zerovalent cerium for catalytic degradation of carbamazepine and colorimetric sensing of H2O2

This study reported the chemical reduction method based synthesis of ionic liquid (IL) functionalized nano-zerovalent cerium (nZVCe) for the degradation of carbamazepine (CBZ) and colorimetric detection of H2O2. Carbamazepine is an important class of emerging water pollutants while H2O2 is produced as a major by-product by living organisms during metabolism. The synthesized IL-nZVCe showed high efficiency towards CBZ degradation and H2O2 detection. The use of advanced characterization techniques showed the prepared material to be highly crystalline and of high surface area, i.e., 85 m2/g. The IL-nZVCe caused 56% removal of CBZ, however, the use of H2O2 and IL-nZVCe promoted the removal of CBZ to 85% under 80 min treatment time using [IL-nZVCe]0, [CBZ]0 and [H2O2]0 as 0.5 g/L, 10 mg/L and 40 mg/L, respectively. IL-nZVCe/H2O2 yielded ●OH which showed high reactivity of 5.40 × 109 (M s)–1 with CBZ and played active role in CBZ degradation. Removal of CBZ was inhibited in the presence of ●OH scavengers. The IL-nZVCe/H2O2–mediated removal of CBZ was promoted under the conditions of high [H2O2]0, high [IL-nZVCe]0 and low [CBZ]0. IL-nZVCe/H2O2 was also highly effective in TOC removal of CBZ. The IL-nZVCe showed high reusability than nZVCe. The acute and chronic toxicities of CBZ degradation products identified by LC–MS analysis were estimated. The conversion of CBZ into non-toxic acetate suggests high potential of the IL-nZVCe/H2O2 into remediation and detoxification of CBZ.

Cobalt doped ceria catalysts for the oxidative abatement of gaseous pollutants and colorimetric detection of H2O2

The development of cost-effective catalysts prepared via simple methods is an urge for their use in pollutant abatement. Here, cobalt doping was used to improve the oxidizing nature of nanoceria, and the catalysts prepared via precipitation followed by wet impregnation were effectively used in the simultaneous oxidation of gaseous pollutants carbon monoxide and hydrocarbon as well as in the colorimetric sensing of H2O2. Material characterization studies revealed the effective incorporation of Co to the nano CeO2 lattice at lower concentrations. The improved oxygen storage capacity and reducibility of CeO2 upon Co doping were evident from the Raman spectroscopic analysis and temperature-programmed reduction of hydrogen. 100% activity is observed in the simultaneous CO and propane oxidation at 450 °C and the Co doped system additionally displayed a wide detection range and low detection limit for H2O2, which is relevant in biochemical sensing.

Graphene oxide and CuO double quantum dot composites (GOQD-q-CuO) with enhanced haloperoxidase-like activity and its application in colorimetric detection of H2O2 and glucose

We report herein, double quantum dot composites of graphene oxide and CuO (GOQD-q-CuO), formed by a low-temperature solution process, possess enhanced haloperoxidase (HPO)-like catalytic activity, which catalyze the oxidation of Cl− by H2O2 to generate reactive chlorine species (RCS). A sensitive and selective colorimetric sensor was then developed via the oxidation of 3,3ʹ,5,5ʹ-tetramethylbenzidine (TMB) by the GOQD-q-CuO catalytic system through the generation of RCS for H2O2 and glucose detection, with detection limits of 0.5 and 2.5 μM and linear ranges between 2.5–200 and 5–400 μM, respectively. This sensor was further applied to glucose detection in clinical serum samples showing no significant differences with the hexokinase method. Additionally, we demonstrate that the GOQD modulates the catalytic activity of q-CuO by reversing its zeta potential, producing an overall negatively charged surface, therefore GOQD-q-CuO has much higher affinity than CuO to the positively charged chromogenic substrate TMB, yielding higher HPO-like activity. Moreover, the presence of Cl− accelerates electron transfer to facilitate Cu2+ reduction to Cu+ on the GOQD-q-CuO surface, speeding up the overall catalytic reaction for the RCS generation, therefore, higher detection sensitivity was achieved.

Enhanced synergistic effects from multiple iron oxide nanoparticles encapsulated within nitrogen-doped carbon nanocages for simple and label-free visual detection of blood glucose

Hollow-structured carbon materials play a crucial role in research of biosensors, energy storage and nanomedicine as a kind of material with advantages like high surface area, tunable pore volume, excellent mechanical properties, and good biocompatibility. Herein, we developed a simple, facile and controllable method for synthesis of Fe3O4 nanoparticles encapsulated in hollow carbon nanocages (FNHCs) with SiO2 nanospheres as a sacrificial template. Owing to the unique structure of multiple Fe3O4 nanoparticles cores integrated with N-doped carbon nanocages, the as-synthesized FNHCs exhibited greatly enhanced peroxidase mimicking activity with extremely high signal-to-noise ratio of ∼91 fold. Also, it was found that the FNHCs possessed a higher peroxidase-like activity than that of other similar-structured Fe3O4 architectures (e.g. Fe3O4@C NPs). The resulting steady-state kinetic curve demonstrated the enzymatic activity of FNHCs with classic Michaelis–Menton kinetics following a ping-pong mechanism. On the basis of the superior enzymatic activity, the FNHCs performed as a high-efficiency peroxidase mimic, realizing facile, label-free, highly sensitive/selective colorimetric detection of H2O2 and glucose. Furthermore, the colorimetric sensor successfully determined glucose in patients’ serum samples with high accuracy and precision, suggesting great potential for real applications.

A facile preparation of FePt-loaded few-layer MoS2 nanosheets nanocomposites (F-MoS2-FePt NCs) and their application for colorimetric detection of H2O2 in living cells

BackgroundRapid and sensitive detection of H2O2 especially endogenous H2O2 is of great importance for series of industries including disease diagnosis and therapy. In this work, uniform FePt nanoparticles are successfully anchored onto Few-layer molybdenum disulfide nanosheets (F-MoS2 NSs). The powder X-ray diffraction, transmission electron microscopy, UV–Vis spectra and atomic force microscopy were employed to confirm the structure of the obtained nanocomposites (F-MoS2-FePt NCs). The prepared nanocomposites show efficient peroxidase-like catalytic activities verified by catalyzing the peroxidation substrate 4,4′-diamino-3,3′,5,5′-tetramethylbiphenyl (TMB) with the existence of H2O2.ResultsThe optimal conditions of the constructed colorimetric sensing platform is proved as 35 °C and pH 4.2. Under optimal catalytic conditions, the detection limit for H2O2 detection reaches 2.24 μM and the linear ranger is 8 μM to 300 μM. Furthermore, the proposed colorimetric sensing platform was successfully utilized to detect the intracellular H2O2 of cancer cells (MCF-7).ConclusionsThese findings indicated that the F-MoS2-FePt-TMB-H2O2 system provides a potential sensing platform for hydrogen peroxide monitoring in living cells.

Intrinsic peroxidase-like activity of Cu2ZnSn(SxSe1-x)4 nanocrystals, and their application to the colorimetric detection of H2O2.

Nanocrystals (NCs) of type Cu2ZnSn(SxSe1-x)4 (CZTSSe) were prepared via a solvothermal approach. They are shown to be highly efficient peroxidase (POx) mimics for colorimetric detection of H2O2. By varying the molar ratio of S and Se during preparation, the NCs showed different crystal structures, morphologies, surface properties, and POx-like activities. Among them, the type CZTSSe-0.25 NCs exhibit the strongest POx-like activities towards the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of H2O2 to generate a blue product. The enhanced activity is attributed to its more negative potential and larger specific surface of the NCs. Based on these findings, a rapid and ultrasensitive method was developed for the visual and colorimetric determination of H2O2. The method is selective, and the NCs are reusable and long-term stable. The detection limit of H2O2 is 50nM. Kinetic and active species trapping experiments were performed to elucidate the POx-like mechanism of the NCs. Graphical abstract Schematic presentation of the process of Cu2ZnSn(SxSe1-x)4 nanocrystals catalyzing the oxidation of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to induce a typical blue color reaction, which can be applied in colorimetric detection of H2O2.

Synthesis of Surface-Modification-Oriented Nanosized Molybdenum Disulfide with High Peroxidase-Like Catalytic Activity for H2 O2 and Cholesterol Detection.

Abnormal H2 O2 and cholesterol levels are closely related to many diseases. This work reports a facile process for the synthesis of oxidized glutathione (GSSG)-modified MoS2 nanosheets (MoS2 -GSSG NSs). The biocompatible MoS2 -GSSG NSs have good dispersibility and high affinity to the substrate 3,3',5,5'-tetramethylbenzidine (TMB), which is beneficial for improving peroxidase-like catalytic activity of MoS2 . The high peroxidase-like activity of MoS2 -GSSG NSs was applied as a robust nanoplatform for low-cost, rapid, and highly effective colorimetric detection of H2 O2 and total/free cholesterol. Moreover, the peroxidase-like catalytic mechanism was studied by the steady-state kinetics method. The catalytic activity was remarkably high at a wide range of pH (2.4-7.0) and temperature values (25-70 °C). The cholesterol was catalyzed by cholesterol oxidase (ChOx) in the presence of O2 to generate H2 O2 , which oxidized TMB to generate a blue-colored product (oxTMB) under the catalysis of MoS2 -GSSG NSs. The detection limit (DL) of total cholesterol and H2 O2 was as low as 5.36 and 0.51 μm, respectively. The linear ranges for detecting cholesterol and H2 O2 were from 5.36 to 800 μm and from 0.51 to 50 μm, respectively. This method was also successfully applied to the detection of cholesterol in serum. The detection concentration of total cholesterol was consistent with that of the value detected by the blood biochemical method used in the clinic.

Oxidation of o‐phenylenediamine to 2,3‐diaminophenazine in the presence of cubic ferrites MFe2O4 (M = Mn, Co, Ni, Zn) and the application in colorimetric detection of H2O2

Metal ferrites nanocrystallites, MFe2O4 (M = Mn, Co, Ni, Zn) were prepared by coprecipitation method and characterized by a combination of physico‐chemical and spectroscopic techniques. MFe2O4 nanoparticles having particle size in the range 10–35 nm were tested as catalysts in the oxidation of o‐phenylenediamine (OPD) to 2,3–diaminophenazine (DAP) using hydrogen peroxide as oxidant at room temperature. Kinetic data was collected for the catalytic oxidation of OPD to DAP by monitoring the UV–vis absorbance at 415 nm and fit well to the Michaelis–Menten model yielding kinetic parameters Km (Michaelis–Menten constant) and Vmax (maximum rate of reaction). MnFe2O4 nanoparticles provide the highest catalytic activity in the oxidation of OPD to DAP at room temperature. A colorimetric method was developed based on the MnFe2O4/OPD system for the detection of H2O2 in reaction solution. The method has a detection limit of 30 μM for H2O2 and wide linear range.

Colorimetric detection of glucose using lanthanum-incorporated MCM-41

In this study, lanthanum-containing mesoporous MCM-41 (La-MCM-41) with different amount of lanthanum were synthesized and were used for colorimetric detection of glucose. As prepared La-MCM-41 were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The quantitative amounts of incorporated lanthanum into MCM-41 structure were estimated by energy dispersive X-ray spectrometry. The prepared La-MCM-41 provided high intrinsic peroxidase-like activity in the presence of peroxidise 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2 for accurate determination of glucose. This process produced a blue color in aqueous solution that directly relates to H2O2 concentration. The effect of different parameters such as the content of incorporated lanthanum, pH, temperature and time of reaction on the peroxidase-like activity was studied. The colorimetric detection of H2O2 was led to a linear dynamic range from 50 to 1000 μM (r2 = 0.9988) and low detection limit of 37.5 μM for glucose in aqueous solution. These results are comparable (close to) or better than some previous reports. Thus, La-MCM-41 can be used as admirable alternative design for colorimetric sensing of glucose.

Iron Mesh-Based Metal Organic Framework Filter for Efficient Arsenic Removal.

Efficient oxidation from arsenite [As(III)] to arsenate [As(V)], which is less toxic and more readily to be adsorbed by adsorbents, is important for the remediation of arsenic pollution. In this paper, we report a metal organic framework (MIL-100(Fe)) filter to efficiently remove arsenic from synthetic groundwater. With commercially available iron mesh as a substrate, MIL-100(Fe) is implanted through an in situ growth method. MIL-100(Fe) is able to capture As(III) due to its microporous structure, superior surface area, and ample active sites for As adsorption. This approach increases the localized As concentration around the filter, where Fenton-like reactions are initiated by the Fe2+/Fe3+ sites within the MIL-100(Fe) framework to oxidize As(III) to As(V). The mechanism was confirmed by colorimetric detection of H2O2, fluorescence, and electron paramagnetic resonance detection of ·OH. With the aid of oxygen bubbling and Joule heating, the removal efficiency of As(III) can be further boosted. The MIL-100(Fe)-based filter also exhibits satisfactory structural stability and recyclability. Notably, the adsorption capacity of the filter can be regenerated satisfactorily. Our results demonstrate the potential of this filter for the efficient remediation of As contamination in groundwater.

Protein‐Directed Metal Oxide Nanoflakes with Tandem Enzyme‐Like Characteristics: Colorimetric Glucose Sensing Based on One‐Pot Enzyme‐Free Cascade Catalysis

AbstractIt is difficult and significant to realize the aim of “one‐pot” and “nonenzyme” for traditional colorimetric detection of blood glucose. The synthesis of nanomaterials with 2D morphology is also a challenge for the bovine serum albumin (BSA)‐directed method. Here, the BSA‐directed synthesis avenue for metal oxide with 2D nanomorphology is developed. MnO2 nanoflakes (NFs) with controllable morphology can be obtained by changing the synthesis conditions. Fortunately, not only is the glucose oxidase (GOx)‐like nanozyme (MnO2 NFs) discovered, but MnO2 NFs also show dual enzyme activities (GOx‐like activity and peroxidase‐like activity) in similar pH range. That is to say, a “tandem nanozyme” (nanomaterial with tandem enzyme‐like characteristics) is presented here. Further, the one‐pot nonenzymatic strategy is proposed for the colorimetric detection of glucose, where the oxidation of glucose and the colorimetric detection of H2O2 are simultaneously conducted under the catalysis of the single nanozyme (MnO2 NFs). The method shows high sensitivity, low limit of detection, and short detection time, due to the proximity effect and in situ reaction. The as‐synthesized 2D tandem nanozyme expands the species of nanozymes, and the proposed strategy breaks traditional colorimetric detection process, accomplishing the purposes of “one‐pot” and “nonenzyme” in the true sense.

Bioinspired Synthesis of Cu2+ -Modified Covalent Triazine Framework: A New Highly Efficient and Promising Peroxidase Mimic.

Artificial enzymes is an emerging field of research owing to the remarkable advantages of enzyme mimics over their natural counterpart, including tunable catalytic efficiencies, lower cost, ease of preparation, and excellent tolerance to variations of the reaction system. Herein, we report an efficient peroxidase mimic based on a copper-modified covalent triazine framework (CCTF). Owing to its unique specific surface area, atomically dispersed active Cu sites, efficient electron transfer, and enhanced photo-assisted enzyme-like activity, the CCTF showed enhanced peroxidase-like enzyme activity. Therefore, copper modification represents an effective route to tailor the peroxidase-like activity of the covalent triazine frameworks. Furthermore, the mechanism of the enhanced peroxidase-like activity and stability of the CCTF were investigated. As a proof of concept, the CCTF was used for the colorimetric detection of H2 O2 and decomposition of organic pollutants. This work provides a new strategy for the design of enzyme mimics with a broad range of potential applications.

Colorimetric Detection: Synthesis of RGO/Cu8 S5 /PPy Composite Nanosheets with Enhanced Peroxidase-Like Activity for Sensitive Colorimetric Detection of H2 O2 and Phenol (Part. Part. Syst. Charact. 3/2017)

Colorimetric Detection: Synthesis of RGO/Cu₈ S₅ /PPy Composite Nanosheets with Enhanced Peroxidase-Like Activity for Sensitive Colorimetric Detection of H₂ O₂ and Phenol (Part. Part. Syst. Charact. 3/2017)

Colorimetric detection of H2O2 using flower-like Fe2(MoO4)3 microparticles as a peroxidase mimic

The authors describe the preparation of Fe2(MoO4)3 materials with micrometer dimensions, and show that they are highly efficient peroxidase mimics that can be used in a photometric assay for H2O2. Depending on the experimental conditions of synthesis, the Fe2(MoO4)3 micromaterials display different morphologies, surface properties, and peroxidase-like activities. Among them, Fe2(MoO4)3 with flower-like structure has the largest BET specific surface area and the most negative potential. It exhibits the best peroxidase mimetic activity in catalyzing the oxidation of 3,3′,5,5′-tetramethylbenzidine in the presence of H2O2 to generate a blue-green product. Based on these findings, method was worked out for H2O2 determination that allows both visual and photometric read-out. The assay has a detection limit as low as 0.7 μM, is selective and practical. Given its sensitivity, the method has a good potential with respect to determination of H2O2 in clinical samples but also in oxidase-type of reactions where H2O2 is being produced.