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The Scopoletin-HRP Fluorimetric Determination of H2O2 in Seawaters—A Plea for the Two-Stage Protocol
摘要： A single solution protocol has been widely used for the ?uorimetric determination of H2O2 in natural waters by its bleaching of the ?uorescing scopoletin in the presence of the enzyme horseradish peroxidase (HRP). In this protocol, the reaction between scopoletin and H2O2 in the sample and the subsequent internal additions, and the measurements of the ?uorescence are all carried out at a single pH in a ?uorometer cell. It is found that this protocol is prone to four sources of possible error. The variability in the reaction stoichiometry between scopoletin and H2O2 in the presence of varying amounts of excess scopoletin, the effect of pH on the rate of reaction between scopoletin and H2O2, the photobleaching of scopoletin, and the de-activation of HRP. These possible sources of error can be circumvented in a two-stage protocol in which the reaction between H2O2 and scopoletin is carried out immediately upon sampling at a pH of 7, and the measurement of the ?uorescence is carried out later on at a pH of 9. It should be the protocol of choice. Furthermore, in the two-stage protocol, after the initial reaction between H2O2 and scopoletin, the sample may be stored at room temperature for six days and at 4 ?C for at least a month before its ?uorescence is measured. This option can signi?cantly reduce the logistics in the ?eld.
关键词： hydrogen peroxide,?uorimetric determination,horseradish peroxidase,scopoletin
更新于2025-09-09 09:28:46
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Optical sensing platform for colorimetric determination of silver nanoprisms and its application for hydrogen peroxide and glucose detections using a mobile device camera
摘要： Silver nanoprisms (AgNPrs) have a unique localized surface plasmon resonance, resulting in strong absorption and scattering within the visible light region. In this work, we propose the image acquisition from colloidal solutions of AgNPrs using a combination of transmitted and scattering lights. The developed measurement technique could be carried out by separately recording transmitted and scattering images of the solutions, using a mobile device camera prior to calculation of empirical absorption value (IA). IA value of green for AgNPrs solutions was found in agreement with the absorption spectra obtained using a conventional spectroscopic technique. This technique was utilized for the quantifications of hydrogen peroxide and glucose. The good linearities between ΔIA and those typical analytes were observed. The limit of detection for typical biosensor of glucose was 19.8 μM. As such, we expect the methodology herein developed for hydrogen peroxide and glucose determinations by means of monitoring the color change of transmitted and scatting images from solutions, to contribute to the development of simple, rapid, and reliable detection systems to be further applied in biochemical analysis and clinical diagnosis, as well as in household biosensor applications.
关键词： silver nanoprisms,glucose sensor,hydrogen peroxide sensor,localized surface plasmon resonance,colorimetric method
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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Observed Dramatically Improved Catalysis of Ag Shell on Au/Ag Core-Shell Nanorods is Due to Silver Impurities Released During Etching Process
摘要： Core/shell bimetallic nanoparticles are highly popular in electrocatalysis; it is argued that the core metal enhances the catalytic properties of the shell. We have investigated the electrocatalytic properties of Au/Ag core-shell nanorods (Au/Ag NRs) where Ag shell was thinned by aging in the presence of cetyltrimethylammonium bromide. We observed excellent electrocatalysis toward hydrogen peroxide electroreduction upon decreasing the Ag shell thickness, which would, at first, appear to imply a strong synergistic effect of the Au core with the Ag shell for electrocatalysis. We show, however, that this electrocatalysis is not caused by particular Au/Ag core/shell structures but rather by the presence of residual silver impurities in the form of Ag nanoparticles (Ag NPs) formed during the preparation of the thin-layer silver shell/gold core nanorods.
关键词： bimetallic particles,Au/Ag nanorods,varied shell thickness,physicochemical transformation,hydrogen peroxide catalyst
更新于2025-09-04 15:30:14
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Minireview: Selective production of hydrogen peroxide as a clean oxidant over structurally tailored carbon nitride photocatalysts
摘要： Hydrogen peroxide (H2O2) is a clean oxidant, and its demand has continuously risen in various industries for pulp/paper bleaching, chemical synthesis, wastewater treatment, etc. H2O2 is commercially produced by the anthraquinone method, which has some drawbacks, including (i) toxic solvent, (ii) explosive hydrogen gas as a precursor, and (iii) a high energy input; therefore, a new technology based on cost-effective and green processes is required. Photocatalytic production of H2O2 can be considered the most environmentally benign and economically feasible process because it requires only dissolved oxygen, water, and sunlight. Among various photocatalysts, polymeric carbon nitride (C3N4) is a promising candidate for H2O2 production by virtue of its (i) simple synthesis by a thermal polymerization, (ii) structure consisting of earth-abundant carbon and nitrogen, (iii) effective bandgap size for visible light absorption, and (iv) suitable position of conduction band for reduction of oxygen dissolved in water. In this minireview, the mechanism of H2O2 formation over C3N4 has been discussed, and the strategies to optimize the photocatalytic activity have been summarized regarding structural and surface modification techniques. This overview of diverse methodologies to selectively control electron transfer to dissolved oxygen should be in demand not only for developing new-generation C3N4-based materials, but also for commercialization of solar-light-driven photocatalytic H2O2 production system.
关键词： Hydrogen peroxide,structural modification,Photocatalysis,Carbon nitride,hybridization
更新于2025-09-04 15:30:14
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Electronic Tuning of Metal Nanoparticles for Highly Efficient Photocatalytic Hydrogen Peroxide Production
摘要： We here present an innovative approach to increase the electron density of metallic Pd nanoparticles loaded on TiO2 photocatalysts by coordinating Pd with surface-anchored organic ligands. X-ray photoelectron spectroscopy and X-ray absorption near edge structure measurements confirm the negative charge on the Pd nanoparticle induced by electron donation from amine groups of the ligands. The electronically modified Pd on TiO2 exhibits unprecedentedly high photocatalytic H2O2 production from O2 reduction. Mechanistic investigations suggest that the enhanced performance results from electronic tuning of Pd nanoparticles, leading to enhanced charge separation on TiO2 support, improved activity of Pd nanoparticles as an oxygen reduction center, and improved selectivity for O2 reduction to produce H2O2.
关键词： immobilized organic ligands,oxygen reduction reaction,electronic tuning,hydrogen peroxide,photocatalysis
更新于2025-09-04 15:30:14
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Selectively light-up hydrogen peroxide in hypoxic cancer cells with a novel fluorescent probe
摘要： A novel fluorescent turn-on probe (HCyHP) was developed in a simple two-step synthesis for monitoring of exogenous and endogenous H2O2 levels in biological samples and hypoxic cancer diagnosis.
关键词： hypoxic cancer cells,fluorescent probe,hydrogen peroxide,bioimaging,diagnosis
更新于2025-09-04 15:30:14
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Synthesis and Characterization of <i>N</i> , <i>N</i> ′-Bismesityl Phenanthrene-9,10-diimine and Imine–Nitrone
摘要： The sterically bulky compounds N,N′-bismesityl phenanthrene-9,10-diimine [1] and imine?nitrone [2] were synthesized. To the best of our knowledge, this is the first report of the synthesis of a bulky steric imine?nitrone accessed from the secondary ketimine using urea hydrogen peroxide over methyltrioxorhenium catalyst. Purified compounds were characterized using 1H and 13C NMR, high-resolution mass spectrometry, and infrared spectrometry. We report the first crystal structure of compound 1. Detailed IR bands of compounds 1 and 2 were assigned by comparing experimentally measured spectra to individually animated modes of quantum mechanically computed spectra. We believe these compounds may be of use as bidentate ligands in the synthesis of novel organometallic compounds. The asymmetric N and O coordination sites of compound 2 might impart interesting electronic effects to organometallic compounds compared to the symmetric N,N′-coordination sites of compound 1.
关键词： organometallic compounds,quantum mechanically computed spectra,N,N′-bismesityl phenanthrene-9,10-diimine,urea hydrogen peroxide,imine?nitrone,bidentate ligands,methyltrioxorhenium catalyst
更新于2025-09-04 15:30:14
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Hydrogen Peroxide Responsive Iron-Based Nanoplatform for Multimodal Imaging-Guided Cancer Therapy
摘要： Cancer multimodal phototherapy triggered by hydrogen peroxide has attracted widespread attention as a dominating strategy to increase phototherapeutic efficiency. Herein, a hydrogen peroxide responsive iron oxide nanoplatform, with the diameter of about 50 nm, is fabricated to intracellularly trigger the Fenton reaction and achieve synergistic photodynamic therapy and photothermal therapy. The nanoplatform based on iron oxide nanoparticles is decorated with indocyanine green (ICG, photosensitizer) and hyaluronic acid (HA, targeting molecular) through electrostatic interaction, thus the as-prepared nanoplatform (IONPs-ICG-HA) exhibits excellent active targeting ability and biocompatibility. More importantly, it can effectively utilize the intratumoral overproduced hydrogen peroxide to generate reactive oxygen species for cancer cell killing via intracellular Fenton reactions. In vitro and in vivo experiments reveal that the IONPs-ICG-HA nanocomposites realize effective photoacoustic/photothermal/fluorescence imaging–guided phototherapy, leading to promising hydrogen peroxide responsive cancer theranostics.
关键词： multiple bioimaging,iron oxide,synergistic phototherapy,hydrogen peroxide
更新于2025-09-04 15:30:14
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Enhanced Photocatalytic degradation of methylene blue dye using CuS-CdS nanocomposite under visible light irradiation
摘要： The inorganic nanoparticles based semiconductor photocatalyst has attracted widespread attention for the practical applications in sustainable energy and environmental remediation due to its low cost, eco-friendly, high efficiency and ease of process. CuS, CdS and CuS-CdS nanocomposite photocatalysts have been successfully synthesized by a simple hydrothermal approach. The phase purity, composition and surface morphology of as synthesized nanomaterials were characterized using various analytical techniques. The photocatalytic activities of the as-prepared materials have been evaluated by the degradation of methylene blue (MB) dye in the presence of hydrogen peroxide (H2O2) which served as an oxidant under visible light irradiation. MB dye (10 ppm) was degraded by about 80%, 59% and 99.97% for CuS, CdS and CuS-CdS nanocomposite respectively at 10 min. The results demonstrate that CuS-CdS nanocomposite exhibited excellent photocatalytic activity as compared to the CuS and CdS is which mainly attributed to large surface area, narrow band gap, high adsorbing capacity of the dye and also low recombination of the photo-generated electrons and holes. Further, electrochemical impedance (EI) measurement revealed that as prepared CuS-CdS nanocomposite suggested that as compared to CuS and CdS, the CuS-CdS nanocomposite exhibits rapid migration of photo-induced charge carriers. In addition, the CuS-CdS nanocomposite demonstrated that good stability towards photocatalytic degradation even after repeated usage. Finally, a suitable photocatalytic reaction mechanism has been proposed to indicate the photocatalytic performance of the nanocomposite.
关键词： Methylene blue dyes,hydrogen peroxide,CuS-CdS,photocatalytic activity.,charge carrier
更新于2025-09-04 15:30:14