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Luminescent MOF nanosheets for enzyme assisted detection of H2O2 and glucose and activity assay of glucose oxidase
摘要： 2D metal-organic framework (MOF) nanosheets have emerged as a novel kind of sensing materials due to the large external surface area and accessible active sites on the surface. In this work, we successfully prepared luminescent MOF nanosheets (In-aip) with thickness of 4 nm by the cation-exchange mediated sonication of a 2D connected anionic MOF. Using In-aip as fluorescent sensor, an enzyme assisted system was established for the analysis of H2O2 with the quenching effect of the oxidation product on its emission. The nanosheet morphology of In-aip ensures its high capture efficiency of unstable intermediate, so high sensitivity was achieved (detection limit = 0.87 μM). With high sensitivity and wide quantitative range, this H2O2 sensing system could be used as a universal platform for the analysis of H2O2 related biomolecules and enzymes. By multi-enzyme cascade catalysis, a detection method of glucose and an activity assay of glucose oxidase were developed based on it. This work is the first example of using luminescent MOF nanosheets to bioanalysis and shows their wide application potential.
关键词： Fluorescence,Nanosheets,H2O2,Metal-organic frameworks,Enzyme assisted sensing
更新于2025-09-09 09:28:46
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Modeling and Optimization of the Photocatalytic Reduction of Molecular Oxygen to Hydrogen Peroxide over Titanium Dioxide
摘要： This study focuses on understanding the mechanisms for optimization of the photocatalytic hydrogen peroxide production over TiO2 (Aeroxide P25). Via precise control of the reaction parameters (pH, temperature, catalyst amount, oxygen content, sacrificial electron donor and light intensity) it is possible to tune either the apparent quantum yield or the production rate. As a result of the optimization, apparent quantum yields of up to 19.8 % and production rates of up to 83 μM min-1 were obtained. We also observed a light dependent change of the reaction order and an interdependency of the light intensity and catalyst amount and developed a well-fitting kinetic model for it, which might also be applied to other reactions. Furthermore, a previously unreported inactivation of the photocatalyst in case of water oxidation is described.
关键词： titanium dioxide (TiO2),hydrogen peroxide (H2O2),oxygen reduction,catalyst inactivation,light intensity,photocatalysis
更新于2025-09-09 09:28:46
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Hemoglobin Immobilization on Multiporous Nanofibers of SnO <sub/>2</sub> and Chitosan Composite for Hydrogen Peroxide Sensing
摘要： A multiporous nanofiber (MPNFs) of SnO2 and chitosan has been used for the immobilization of a redox protein, hemoglobin (Hb), onto the surface of glassy carbon electrode (GCE). The multiporous nanofiber of SnO2 that has very high surface area is synthesized by using electrospinning technique through controlling the tin precursor concentration. Since the constructed MPNFs of SnO2 exposes very high surface area, it increases the efficiency for biomolecule-loading. The morphology of fabricated electrodes is examined by SEM observation and the absorbance spectra of Hb/(MPNFs) of SnO2 are studied by UV-Vis analysis. Cyclic Voltammetry and amperometry are employed to study and optimize the performance of the resulting fabricated electrode. After fabrication of the electrode with the Hb and MPNFs of SnO2, a direct electron transfer between the protein’s redox centre and the glassy carbon electrode was established. The modified electrode has showed a couple of redox peak located at ?0.29 V and ?0.18 V and found to be sensitive to H2O2. The fabricated electrode also exhibited an excellent electrocatalytic activity towards the reduction of H2O2. The catalysis currents increased linearly to the H2O2 concentration in a wide range of 5.0 × 10?6–1.5 × 10?4 M. Overall experimental results show that MPNFs of SnO2 has a role towards the enhancement of the electroactivity of Hb at the electrode surface. Thus the MPNFs of SnO2 is a very promising candidate for future biosensor applications.
关键词： Multiporous SnO2 Nanofiber,Hemoglobin,Electrical Contact,H2O2 Sensing,Direct Electrochemistry
更新于2025-09-09 09:28:46
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Imaging of endogenous hydrogen peroxide during the process of cell mitosis and mouse brain development with a near-infrared ratiometric fluorescent probe
摘要： Hydrogen peroxide (H2O2) is emerging as a new second messenger, which plays vital roles in intracellular signaling, thereby triggering physiological variations in terms of proliferation, differentiation, and migration. As known, cell mitosis has closely association to the intracellular level of H2O2, which contribute to the significant effects on the brain development, especially during the critical period of immaturity. Unfortunately, imaging H2O2 in mammalian brain is still challenging. Herein, to further investigate the biological roles of endogenous H2O2 in cells mitosis, we develop a near-infrared ratiometric fluorescent probe Cy-PFS for specifically imaging of endogenous H2O2 in cells and in vivo. Employing the probe Cy-PFS, we examine the critical effects of endogenous H2O2 on cells proliferation in live hippocampal neurons cells, our results provide strong evidences for H2O2 signaling in cell mitosis through growth factor signaling. Furthermore, we successfully demonstrate the close association of endogenous H2O2 level changes with the brain development at various stages. We envision that this present probe has potential as a promising useful chemical imaging tool for exploring the roles of H2O2 in cell mitosis.
关键词： cell mitosis,Hydrogen peroxide,endogenous H2O2,brain development,near-infrared ratiometric fluorescent probe
更新于2025-09-09 09:28:46
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Identification and characterization of a core set of <scp>ROS</scp> wave‐associated transcripts involved in the systemic acquired acclimation response of Arabidopsis to excess light
摘要： Systemic acquired acclimation (SAA) plays a key role in optimizing growth and preventing damages associated with fluctuating or abrupt changes in the plant environment. To be effective, SAA has to occur at a rapid rate and depend on rapid signaling pathways that transmit signals from affected tissues to all parts of the plant. Although recent studies identified several different rapid systemic signaling pathways that could mediate SAA, very little is known about the extent of their involvement in mediating transcriptomic responses. Here we reveal that the systemic transcriptomic response of plants to excess light stress is extensive in its context and involves an early (2 minute) and transient stage of transcript expression that includes thousands of genes. This early response is dependent on the respiratory burst oxidase homolog D protein, and the function of the reactive oxygen species (ROS) wave. We further identify a core set of transcripts associated with the ROS wave and suggest that some of these transcripts are involved in linking ROS with calcium signaling. Priming of a systemic leaf to become acclimated to a particular stress during SAA involves thousands of transcripts that display a rapid and transient expression pattern driven by the ROS wave.
关键词： Arabidopsis thaliana,H2O2 signaling,systemic signaling,Reactive oxygen species (ROS) wave,Transcriptomics,light stress,MYB30,systemic acquired acclimation (SAA),WRKY
更新于2025-09-09 09:28:46
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1T-Phase Tungsten Chalcogenides (WS <sub/>2</sub> , WSe <sub/>2</sub> , WTe <sub/>2</sub> ) Decorated with TiO <sub/>2</sub> Nanoplatelets with Enhanced Electron Transfer Activity for Biosensing Applications
摘要： Layered transition metal dichalcogenides (TMDs) have received a great deal of attention due to fact that they have varied band gap, depending on their metal/chalcogen composition and on the crystal structure. Furthermore, these materials demonstrate great potential application in a myriad of electrochemical technologies. Heterogeneous electron transfer (HET) abilities of TMD materials toward redox-active molecules occupy a key role in their suitability for electrochemical devices. Herein, we introduce a promising biosensing strategy based on improved heterogeneous electron transfer rate of WS2, WSe2, and WTe2 nanosheets exfoliated using tert-butyllithium (t-BuLi) and n-butyllithium (n-BuLi) intercalators decorated with vertically aligned TiO2 nanoplatelets. By comparison of all the nanohybrids, decoration of TiO2 on t-BuLi WS2 (TiO2@t-BuLi WS2) results in the fastest HET rate of 5.39 × 10?3 cm s?1 toward ferri/ferrocyanide redox couple. In addition, the implications of decorating tungsten dichalcogenides (WX2) with TiO2 nanoplatelets in enzymatic biosensor applications for H2O2 detection are explored. TiO2@t-BuLi WS2 outperforms all other nanohybrid counterparts and is demonstrated to be an outstanding sensing platform in enzyme-based biosensor with wide linear range, low detection limit, and high selectivity. Such conceptually new electrocatalytic detection systems shall find the way to the next generation biosensors.
关键词： heterogeneous electron transfer,H2O2 detection,nanosheets,TiO2 nanoplatelets,transition metal dichalcogenides
更新于2025-09-04 15:30:14
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Photooxidative Removal of p-Nitrophenol by UV/H2 O2 Process in a Spinning Disk Photoreactor: Influence of Operating Parameters
摘要： In this paper, spinning disk photoreactor (SDP) has been used for the removal of a refractory pollutant, namely p-nitrophenol (PNP), in UV/H2O2 process. The effect of various parameters such as the plate type in the SDP, concentration of oxidant (H2O2), fluid volume, initial concentration of PNP, distance of the lamps from the spinning disk, distance of the lamps from each other, pH, and rotation speed of the spinning disk in the removal efficiency has been investigated. The results indicated that the use of scrobiculate disc instead of flat disc significantly increased the removal percentage of PNP from 46 to 100 % for the irradiation time of 20 min; it also increased with increasing H2O2 concentration, but the increase in fluid volume and the initial concentration of PNP reduced the removal percentage of PNP in the SDP. The increase in the distance of UV lamps from each other and from disc surface in the SDP reduced the removal percentage of PNP. However, the increase in pH to 5.5 increased removal efficiency while increasing pH above 5.5 reduced PNP removal efficiency. The disk rotation speed from 0 to 90 rpm increased the removal percentage from 49 to 70 % for the irradiation time of 5 min, but increasing the rotation speed to more than 90 rpm reduced the removal efficiency.
关键词： UV/H2O2,spinning disk photoreactor,p-nitrophenol,Advanced Oxidation Processes (AOPs)
更新于2025-09-04 15:30:14
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Exosome-like Nanozyme Vesicles for H2O2-responsive Catalytic Photoacoustic Imaging of Xenograft Nasopharyngeal Carcinoma
摘要： Photoacoustic imaging (PAI) is an attractive imaging modality, which is promising for clinical cancer diagnosis due to its advantages on deep tissue penetration and fine spatial resolution. However, few tumor catalytic/responsive PAI strategies are developed. Here, we design an exosome-like nanozyme vesicle for in vivo H2O2-responsive PAI of nasopharyngeal carcinoma (NPC). The intrinsic peroxidase-like activity of graphene quantum dot nanozyme (GQDzyme) effectively converts the 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) into its oxidized form in the presence of H2O2. The oxidized ABTS exhibits strong near-infrared (NIR) absorbance, rendering it to be an ideal contrast agent for PAI. Thus, GQDzyme/ABTS nanoparticle is a novel type of catalytic PAI contrast agent which is sensitive to H2O2 produced from NPC cells. Furthermore, we develop an approach to construct exosome-like nanozyme vesicle via biomimetic functionalization of GQDzyme/ABTS nanoparticle with natural erythrocyte membrane modified with folate acid. In vivo animal experiments demonstrated that, this exosome-like nanozyme vesicle effectively accumulated in NPC and selectively triggered catalytic PAI for NPC. In addition, our nanozyme vesicle exhibits excellent biocompatibility and stealth ability for long blood circulation. Together, we demonstrate that GQDzyme/ABTS based exosome-like nanozyme vesicle is an ideal nanoplatform for developing deep-tissue tumor-targeted catalytic PAI in vivo.
关键词： photoacoustic imaging,nasopharyngeal carcinoma,H2O2-responsive,graphene quantum dot nanozyme,exosome-like vesicle,erythrocyte membranes
更新于2025-09-04 15:30:14
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Confocal Fluorescence Microscopy and Kinetics of the Cr3+-Chromate Ion Oxidation Equilibria at the Solid Liquid Interface
摘要： Silica-borax pearl samples impregnated with 0.17 and 0.64% Cr3+ were characterized by specific surface area measurements, UV-Vis spectroscopy, energy-dispersive X-ray fluorescence and laser-scanning confocal microscopy. Pearl stability against oxidizing conditions was tested by adding samples to an aqueous hydrogen peroxide solution. The reaction was examined by UV-Vis spectroscopic measurements of the supernatant and laser-scanning confocal microscopy images of the substrate. Overall, hydrogen peroxide-induced Cr3+ to Cr6+ oxidation across the solid-liquid interface promoted solid matrix cleavage pearl degradation and concomitant formation of multiple scattering centers was observed. A dual-detection scheme was employed in the confocal microscopy measurements allowing us to separate scattering and absorptive contributions to the observed signals. The confocal microscopy images indicate that Cr3+ oxidation induced by hydrogen peroxide solutions occurs throughout the entire pearl sample and indicate that oxidation reactions induce leakage of chromate ion into aqueous solutions.
关键词： energy dispersive X-ray fluorescence,confocal fluorescence microscopy,chromium mobility,H2O2 oxidation equilibria,mass transfer phenomena,solid liquid interfaces
更新于2025-09-04 15:30:14