Detection Of Hydroxyl Radicals Research Articles

Role of alumina particles in chemical-mechanical synergies in ruthenium polishing

Abrasive particles are usually considered to only play a "mechanical wear" role in the metal chemical mechanical polishing (CMP) process, neglecting their influence on chemical reactions. This study reveals the chemical role of Al2O3 particles in ruthenium (Ru) CMP by comparing the properties and polishing performance of Al2O3-SiO2 mixed slurry and pure SiO2 slurry. Several testing methods are used to investigate the mechanical and chemical actions of Al2O3 particles, including particle size distribution, Zeta potential, electrochemical reaction kinetics, oxide layer property and hydroxyl radical detection test. The results indicate that Al2O3 particles enhance the mechanical action by reducing the Zeta potential, and promote the chemical action by catalyzing hydrogen peroxide to produce hydroxyl radical (Fenton-like reaction) on Ru surface. These increase the material removal rate of Ru CMP with mixed slurry by nearly 5 times, while the surface roughness decreases by 60 %. The mechanism of chemical reaction promoted by increasing the hydroxyl radical concentration on Ru surface is confirmed from the aspects of increased corrosion current, oxide layer thickness and proportion of higher-valence Ru oxide (RuO2) in the oxide layer. Among them, the thickened oxide layer is a significant factor contributing to the substantial improvement in the material removal rate of Ru and the reduction in surface roughness. This study enhances the understanding of the chemical-mechanical synergistic mechanism of abrasive particles in metal polishing and elucidates the principle of this mechanism on promoting material removal and surface quality. It also provides new research ideas and theoretical guidance for efficient and high-quality metal polishing.

A dual-emission mitochondria targeting fluorescence probe for detecting hydroxyl radical and its generation induced by cellular activities

The hydroxyl radical (•OH), a member of the reactive oxygen species (ROS) family, is mainly reactive and toxic, promotes the harmful effects of oxidative stress, and ultimately leads to programmed cell death and organ malfunction. In order to assess the function that the hydroxyl radical (•OH) plays in physiological and pathological processes, it is crucial to detect and image the radical with high sensitivity and selectivity in biological systems. Here, a novel dual-emission fluorescence probe was designed based on a coumarin-quinoline scaffold that could detect coumarin-quinoline •OH with high selectivity, sensitivity, fast responses, and good biocompatibility. This probe is mito-targeting with two well-resolved (172 nm) emission peaks and can be used to image endogenous •OH in living cells and zebrafish under complex conditions. Besides, by tracking the level of hydroxyl radical in mitochondria and nuclei, we have revealed the two different pathways of •OH generation that occurs in cell apoptosis induced by β-lapachone (β-Lap) and lipopolysaccharide (LPS) for the first time by fluorescence probe.

Recent Advances in Detection of Hydroxyl Radical by Responsive Fluorescence Nanoprobes.

Hydroxyl radical (•OH), a highly reactive oxygen species (ROS), is assumed as one of the most aggressive free radicals. This radical has a detrimental impact on cells as it can react with different biological substrates leading to pathophysiological disorders, including inflammation, mitochondrion dysfunction, and cancer. Quantification of this free radical in-situ plays critical roles in early diagnosis and treatment monitoring of various disorders, like macrophage polarization and tumor cell development. Luminescence analysis using responsive probes has been an emerging and reliable technique for in-situ detection of various cellular ROS, and some recently developed •OH responsive nanoprobes have confirmed the association with cancer development. This paper aims to summarize the recent advances in the characterization of •OH in living organisms using responsive nanoprobes, covering the production, the sources of •OH, and biological function, especially in the development of related diseases followed by the discussion of luminescence nanoprobes for •OH detection.

Dimethyl Sulfoxide: An Ideal Electrochemical Probe for Hydroxyl Radical Detection.

In situ and real-time determination of hydroxyl radicals (•OH) in physiological and pathological processes is a great challenge due to their ultrashort lifetime. Herein, an electrochemical method was developed by using dimethyl sulfoxide (DMSO) as a trapping probe for rapid determination of •OH in aqueous solution. When DMSO reacted with •OH, an intermediate product methane sulfinic acid (MSIA) was formed, which can be electrochemically oxidized to methanesulfonic acid (MSA) on the glassy carbon electrode (GCE), resulting in a distinct voltammetric signal that is directly proportional to the concentration of •OH. Other commonly encountered reactive oxygen species (ROS), including hypochlorite anions (ClO-), superoxide anions (O2•-), sulfate radicals (SO4•-), and singlet oxygen (1O2), have showed no interference for •OH determination. Thus, an electrochemical method was developed for the determination of •OH, which exhibits a wide linear range (0.4-5120 μM) and a low limit detection of 0.13 μM (S/N = 3) and was successfully applied for the quantification of •OH in aqueous extracts of cigarette tar (ACT). Alternatively, the same reaction mechanism is also applicable for the determination of DMSO, in which a linear range of 40-320 μM and a detection limit 13.3 μM (S/N = 3) was achieved. The method was used for the evaluation of DMSO content in cell cryopreservation medium. This work demonstrated that DMSO can serve as an electrochemical probe and has valuable application potential in radical study, biological research, and environmental monitoring.

Ratiometric electrochemical determination of hydroxyl radical based on graphite paper modified with metal-organic frameworks and impregnated with salicylic acid.

Hydroxyl radical (•OH) detection is pivotal in medicine, biochemistry and environmental chemistry. Yet, electrochemical method-specific detection is challenging because of hydroxyl radicals'high reactivity and short half-life. In this study, we aimed to modify the electrode surface with a specific recognition probe for •OH. To achieve this, we conducted a one-step hydrothermal process to fabricate a CoZnMOF bimetallic organic framework directly onto conductive graphite paper (Gp). Subsequently, we introduced salicylic acid (SA) and methylene blue (MB), which easily penetrated the pores of CoZnMOF. By selectively capturing •OH by SA and leveragingtheelectrochemical signal generated by the reaction product, we successfully developed an electrochemical sensor Gp/CoZnMOF/SA + MB. The prepared sensor exhibited a good linear relationship with •OH concentrations ranging from 1.25 to 1200 nM, with a detection limit of 0.2 nM. Additionally, the sensor demonstrated excellent reproducibility and accuracy due to the incorporation of an internal reference. It exhibited remarkable selectivity for •OH detection, unaffected by otherelectrochemically active substances. The establishment of this sensor provides a way to construct MOF-modified sensors for the selective detection of other reactive oxygen species (ROS), offering a valuable experimental basis for ROS-related disease research and environmental safety investigations.

Constructing Z-Scheme 3D WO3@Co2SnO4 Heterojunction as Dual-Photocathode for Production of H2O2 and In-Situ Degradation of Organic Pollutants

As photoelectrochemical catalyst material, Z-scheme heterojunction 3D WO3@Co2SnO4 composites were designed through a hydrothermal-calcination method. The morphology and structure were characterized by SEM, EDS, XRD, XPS, DRS, and Mott–Schottky analysis, and the photoelectrochemical properties were explored with the transient photocurrent and electrochemical impedance. The construction of Z-scheme heterojunction markedly heightened the separation efficiency of photogenerated electron-hole pairs of WO3 and enhanced the light absorption intensity, retaining the strong redox ability of the photocatalyst. The 3D WO3@Co2SnO4 was used as a photocathode for production of H2O2. Under the optimal reaction conditions, the yield of H2O2 can reach 1335 μmol·L−1·h−1. The results of free radial capture and rotating disc test revealed the existence of direct one-step two-electron and indirect two-step one-electron oxygen reduction to produce H2O2. Based on the excellent H2O2 production performance of the Z-scheme heterojunction photoelectrocatalytic material, 3D WO3@Co2SnO4 and stainless-steel mesh were used to construct a dual-cathode photoelectric-Fenton system for in-situ degradation of a variety of pollutants in water, such as dye (Methyl orange, Rhodamine B), Tetracycline, sulfamethazine, and ciprofloxacin. The fluorescence spectrophotometry was used to detect hydroxyl radicals with terephthalic acid as a probe. Also, the photocatalytic degradation mechanism was revealed, indicating the dual-cathode photoelectron-Fenton system displayed satisfactory potential on degradation of different types of environmental pollutants. This work provided insights for designing high-activity photoelectrocatalytic materials to produce H2O2 and provided possibility for construction of a photoelectric-Fenton system without extra additions.

Preparation of molecularly imprinted electrochemical sensors for selective detection of hydroxyl radicals based on reduced graphene oxide nanosilver (rGO/AgNPs) composites

An electrochemical sensor for selective detection of hydroxyl radicals (OH) has been developed, which is based on silver nanoparticles and reduced graphene oxide composites (rGO/AgNPs) synthesized in situ by the green reduction method, combined with the electrochemical polymerization method for preparation of molecularly imprinted polymers (MIPs) to modify the screen-printed electrodes. During the assay, the concentration of hydroxyl radicals was obtained by capturing the product 2,5-dihydroxybenzoic acid (2,5-DHBA). Under the optimal experimental conditions, the oxidation peak currents of the target 2,5-DHBA by differential pulse voltammetry (DPV) and its concentration showed a good linear relationship in the concentration ranges of 0.1 ∼ 0.5 μM and 1 ∼ 100 μM, with the limit of detection (LOD) of 0.021 μM. Interference experiments and other studies were also carried out, and the results showed that the sensor has good reproducibility, stability, and selectivity, and the comparison of the detection results with the conventional detection method, high-performance liquid chromatography, indicated the accuracy of the sensor detection, which is a convenient, sensitive, and efficient method for the detection of hydroxyl radicals.

Green Emissive Molybdenum Nanoclusters for Selective and Sensitive Detection of Hydroxyl Radical in Water Samples.

In this work, Cassia tora (C. tora) have been used as a template to synthesize green fluorescent C. tora molybdenum nanoclusters (C. tora-MoNCs) through a green chemistry approach. These C. tora-MoNCs showed a quantum yield (QY) of 7.72% and exhibited a significant emission peak at 498 nm when excited at 380 nm. The as-prepared C. tora-MoNCs had an average size of 3.48 ± 0.80 nm and showed different surface functionality. The as-synthesized C. tora-MoNCs were successfully identified the hydroxyl radical (•OH) via a fluorescence quenching mechanism. Also, fluorescence lifetime and Stern-Volmer proved that after the addition of •OH radicals it was quenched the fluorescence intensity via a static quenching mechanism. The limit of detection is 9.13 nM, and this approach was successfully utilized for sensing •OH radicals in water samples with a good recovery rate.

Quantifying hydroxyl radicals generated by a low-temperature plasma using coumarin: methodology and precautions.

The detection and quantification of hydroxyl radicals (HO˙) generated by low-temperature plasmas (LTPs) are crucial for understanding their role in diverse applications of plasma radiation. In this study, the formation of HO˙ in the irradiated aqueous phase is investigated at various plasma parameters, by probing them indirectly using the coumarin molecule. We propose a quantification methodology for these radicals, combining spectrophotometry to study the coumarin reaction with hydroxyl radicals and fluorimetry to evaluate the formation yield of the hydroxylated product, 7-hydroxycoumarin. Additionally, we thoroughly examine and discuss the impact of pH on this quantification process. This approach enhances our comprehension of HO˙ formation during LTP irradiation, adding valuable insights to plasma's biological applications.

A dual-functional fluorescence probe for detection of Aβ aggregates and hydroxyl radicals

Synchronous detection of Aβ aggregates and reactive oxygen species (ROS) would provide direct insight to reveal the complicated correlations between the two crucial Alzheimer’s disease (AD) hallmarks. Herein, the first fluorescence probe (Quin-HCy) for dual-functional detection of Aβ aggregates and the highly destructive ROS hydroxyl radicals (•OH) is developed. Quin-HCy is designed with a blood-brain barrier (BBB) permeable quinoline fluorophore and a •OH-responsive hydrocyanine moiety. Quin-HCy shows obvious fluorescence increases in response to Aβ aggregates and •OH at 450 nm and 770 nm, respectively. The large spectral shift (∼ 320 nm) is advantageous for the independent detection of these two analytes in two distant channels. Quin-HCy has been used to image •OH in cells through the addition of Fenton reagents, stimulation with PMA and induction of ferroptosis. Most importantly, fluorescence imaging with Quin-HCy shows that significant •OH is generated in Aβ aggregate-treated neuron cells, which provides direct evidence for the high dependence between Aβ aggregates and •OH in the etiology of AD. Besides, Quin-HCy has favorable BBB permeability, and is able to image Aβ plaques and •OH in AD mice brain slices.

A precise method to monitor hydroxyl radical in natural waters based on a fluoride-containing fluorescence probe

In natural waters, hydroxyl radical (OH) can initiate many free radical-induced reactions, oxidizing various inorganic and organic compounds through electron transfer reactions, dehydrogenation reactions, addition reactions, and self-quenching reactions. However, due to its extremely low concentration and short lifetime in natural waters, studies on the quantitative measurement of OH levels are insufficient. In this work, we developed the first quinolinium-based fluorescence probe containing fluoride substituted donor that could detect hydroxyl radicals in the water system. This probe exhibits excellent selectivity towards OH with a large Stokes shift (114 nm) and 23-fold enhancement in fluorescence. Additionally, this probe has been proven to be low toxicity and applied to detect OH in living cells, zebrafish, and natural water samples with good recovery (over 92 %).

Constructing fluorescence probes with fluoride-substituted donors for detecting •OH in living cells and zebrafish

Hydroxyl radicals (•OH) is one of the commonly reactive oxygen species available in biosystem and plays a key role in a number of physiological and pathological processes. Based on our previous study, fluoride could serve as a moderate electron donating group in constructing fluorescence probes. However, there is seldom work on the effects of fluoride-substituted moiety towards the photophysical properties in constructing fluorescence probes. In this work, we developed a series of novel fluorescence probes based on a quinolinium-scaffold containing fluoride substituted donor. From our results, the probe FHyR-3 which has an extended conjugated system could detect hydroxyl radical with high selectivity, sensitivity, and fast response. Furthermore, the probe has the maximum emission at 508 nm with a large stoke shift (114 nm) and exhibits low toxicity, good biocompatibility and mito-targeting. We also demonstrated its capability in tracking hydroxyl radical level in living cells and zebrafish.

Photophysics of 7-hydroxycoumarin 3-carboxylic acid in micelles

7-Hydroxy coumarin-3-carboxylic acid (7-HCCA) is a photoacid that exists in three distinct forms: neutral, anionic and di-anionic. It falls under the category of hydroxy aromatic and carboxy aromatic molecules. This molecule exhibits strong fluorescence and is commonly employed in the detection of hydroxyl radicals. In our study, we utilised absorption and fluorescence spectroscopy to investigate the photophysical behaviour of 7-HCCA in different micellar systems. Through our experiments, we observed that as we varied the pH within the ranges of 2–3, 4–6, 7–10, the three aforementioned forms of 7-HCCA are emerged. Specifically, in cationic surfactants, the dye displayed an equilibrium between two forms of the 7-HCCA in the ground state at any pH. Furthermore, our steady-state excitation studies also proved the presence of an equilibrium between two forms of the 7-HCCA in all cationic systems. By examining the steady-state emission spectra, we also observed the presence of two distinct species in the excited state. When cationic surfactants were introduced, we observed a decrease in the fluorescence intensity and quantum yield compared to that observed in the water medium. It was evident that the photophysical properties of 7-HCCA were modulated with variations of the chain length and head group of the surfactants. In summary, our investigation shed light on the photophysical characteristics of 7-HCCA in different micellar systems with varying the pH. By employing the absorption and fluorescence spectroscopy, we successfully identified the coexistence of multiple forms of 7-HCCA and observed how the cationic surfactants influenced its fluorescence emission properties, ultimately contributing to a deeper understanding of its behaviour in these systems.

Construction of S-Scheme Co2SnO4/graphdiyne heterojunction to promote carrier transfer for efficiently photocatalytic hydrogen evolution characterized with in situ XPS

Graphdiyne (g-CnH2n-2), a novel two-dimensional carbon isomeric material consisting of a network of sp and sp2 co-hybridized hybridized carbons, has been highly regarded for its excellent chemical and physical properties and unique structure since it was first synthesized in 2010. However, as a photocatalyst, its application in the field of hydrogen production is still rare, which is a good opportunity for the field of photochemical catalyze hydrogen production. In this work, a binary catalyst Co2SnO4/graphdiyne was constructed by calcining graphdiyne and CoSn(OH)6 together after grinding. The structure of high-temperature calcination closely linked Co2SnO4 and graphdiyne, which led to an increased contact area and more active sites with faster photogenerated electron transfer efficiency. Therefore, Co2SnO4/graphdiyne showed good photocatalytic hydrogen production efficiency. Under the optimum amount of EY the hydrogen production rate reached 8.79 mmol g−1 h−1, which was 80.11 and 33.70 times higher than that of Co2SnO4 and graphdiyne, respectively. The construction of Co2SnO4/graphdiyne S-scheme heterojunction proved by in-situ XPS, EPR (DMPO-•O2−) experiment and the hydroxyl radical detection experiment retains high redox potential and prolongs the lifetime of photo-generated carriers. The catalyst preparation method in this work is innovative, which provides a general and high-efficiency strategy for applying the graphdiyne-based S-scheme heterojunction photocatalyst to solar energy-hydrogen energy conversion for photocatalytic water decomposition into hydrogen.

The synthesis of tunable fluorescence iron nanoclusters and the detection of pH value and hydroxyl radical

In this work, we developed a novel route for the synthesis of fluorescent iron nanoclusters (Hb-Fe NCs) in aqueous solution with natural protein and amino acid as the original materials. Moreover, the fluorescence emission of Hb-Fe NCs were adjustable from red to blue fluorescence by regulating the dosage of sodium hydroxide in the synthesis process. We have examined the fluorescence response of Hb-Fe NCs in various temperature, metal ions or biomolecules environment, and exhibited excellent stability in the complex environment. Furthermore, the fluorescence of Hb-Fe NCs gradually enhanced as the pH value of environment increased from 5.0 to 9.0. More importantly, the fluorescence of Hb-Fe NCs can be inhibited significantly by hydroxyl radical (OH·).

Studies on the preparation of fly ash-derived Fe-SSZ-13 catalysts and their performance in the catalytic oxidation of NO by H2O2

SSZ-13 zeolite was synthesized from fly ash using a combined alkali fusion hydrothermal method. The optimal synthesis parameters are as follows: NaOH/FA=1.4, SiO2/Al2O3=50, H2O/SiO2=1800, TMAda-OH/Al2O3=7, the amount of SSZ-13-seed=10%, and crystallization time and temperature were 160 °C and 40 h. Based on this, a series of fly ash-based Fe-SSZ-13 catalysts were prepared using three different methods and tested in catalytic oxidation with H2O2 for NO removal. The experiment results showed that the NO removal efficiency catalyzed by Fe-SSZ-13-SSIE, Fe-SSZ-13-LIE and Fe-SSZ-13-IM were 78%, 87% and 84%, respectively. ESR was used to detect hydroxyl radicals, UV-vis, XPS and H2-TPR were applied to test the composition, state and distribution of iron species, while NH3-TPD and Py-FTIR were performed to analyze the intensity and type of acidic sites, and finally to determine the relationship between catalyst structure, active species and catalytic performance in combination with NO removal experiments. The catalytic oxidation mechanism analysis revealed that the excellent catalytic performance can be attributed to the dual function of strong Brønsted acidity on the surface and isolated Fe3+ with high dispersion, which can rapidly decompose H2O2 into ·OH and efficiently achieve NO oxidation. In conclusion, the preparation of fly ash catalysts has great potential for achieving the dual function of waste utilization and pollutant removal.

Flammulina velutipes-derived carbon dots for fluorescence detection and imaging of hydroxyl radical

Monitoring hydroxyl radical (•OH) fluctuation is of great importance to study some relative pathological processes and to predict early diagnosis of diseases. Efficient •OH-responsive fluorescent sensors based on carbon dots (CDs) have been reported, but most researches have focused on the new strategies for the synthesis and doping of the CDs. Herein, a kind of biomass CDs (F-CDs) with Flammulina velutipes (F. velutipes) as the carbon source was prepared by a one-step hydrothermal method without any additional modification. The prepared F-CDs have remarkable sensitivity and selectivity and there is a good linear relationship from 0 to 12 μM with a low detection limit of 95 nM for quantitative •OH assay. With excitation-independent emission, favourable biocompatibility and low toxicity, the F-CDs can penetrate cell membranes as •OH-responsive fluorescent sensors to detect intracellular •OH in A549 cells stimulated by phorbol 12-myristate 13-acetate (PMA) and successfully monitor the •OH concentration levels by the corresponding fluorescence change. Given the combined benefits of the green and eco-friendly approach, the F-CDs show promise as novel theranostics tools for early detection and treatment of related diseases.

Rotating ring-disk electrode method to evaluate performance of electrocatalysts in hydrogen peroxide activation via rapid detection of hydroxyl radicals

One-electron electrochemical reduction of hydrogen peroxide (H2O2) is an effective way to produce hydroxyl radical (•OH), whose yield is greatly dependent on the performance (activity and selectivity) of electrocatalysts. However, the current method to evaluate the performance of electrocatalysts is limited by time-consuming and less sensitive method of •OH detection. Herein, we propose an online rotating ring disk electrode (RRDE) method to evaluate the performance of electrocatalysts in H2O2 activation by rapidly detecting •OH. This method is implemented by determining the current signals on the disk and ring electrodes: the generated •OH from H2O2 reduction on the disk electrode (induce negative disk currents) reacts with H2O2 to produce superoxide radical (O2•−), which migrates to and is oxidized on the ring electrode and generates positive ring currents. The relevance of the ring currents to O2•− and •OH is proved by radical quenching tests and kinetic analysis. The performance of five electrocatalysts were evaluated by both the RRDE method and the terephthalic acid (TPA) fluorescence method, and the consistent results verify the applicability of the RRDE method. Hence, this work facilitates the development of high-performance electrocatalysts for H2O2 activation and bring insights for RRDE-based electroanalytic chemistry.

A highly sensitive and selective artificial nanochannel for in situ detection of hydroxyl radicals in single living cell

As the most aggressive reactive oxygen species (ROS), hydroxyl radical (•OH) can directly modulate the biological ion channel and interfere with the progression of diseases. Inspired by biological •OH-activated ion channel, we reported a novel •OH-regulated glass nanopore functionalized with protoporphyrin Ⅸ (PP) film. This system showed outstanding •OH selective response owing to the ultra-fast reaction between •OH and thiol derivatives. In this case, the PP film is responsible for the changing not only of wettability but also of the inner surface charge. The synergetic effect of the dual transitions can regulate the ion transportation within the nanochannels and enabled tremendous enhancement of responsive efficiency. The detection limit could be achieved down to 1.58 nM. Taking advantage of the excellent analytical performance and mechanical qualities of this glass nanopore, the changes of •OH in single living cells were in situ monitored. Together, this study is beneficial for exploring the role of •OH in pathological events and shows promising potential for biomedical research.

Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy.

The hydroxyl radical (•OH) is one of the most attractive reactive oxygen species due to its high oxidation power and its clean (photo)(electro)generation from water, leaving no residues and creating new prospects for efficient wastewater treatment and electrosynthesis. Unfortunately, in situ detection of •OH is challenging due to its short lifetime (few ns). Using lifetime-extending spin traps, such as 5,5-dimethyl-1-pyrroline N-oxide (DMPO) to generate the [DMPO-OH]• adduct in combination with electron spin resonance (ESR), allows unambiguous determination of its presence in solution. However, this method is cumbersome and lacks the necessary sensitivity and versatility to explore and quantify •OH generation dynamics at electrode surfaces in real time. Here, we identify that [DMPO-OH]• is redox-active with E0 = 0.85 V vs Ag|AgCl and can be conveniently detected on Au and C ultramicroelectrodes. Using scanning electrochemical microscopy (SECM), a four-electrode technique capable of collecting the freshly generated [DMPO-OH]• from near the electrode surface, we detected its generation in real time from operating electrodes. We also generated images of [DMPO-OH]• production and estimated and compared its generation efficiency at various electrodes (boron-doped diamond, tin oxide, titanium foil, glassy carbon, platinum, and lead oxide). Density functional calculations, ESR measurements, and bulk calibration using the Fenton reaction helped us unambiguously identify [DMPO-OH]• as the source of redox activity. We hope these findings will encourage the rapid, inexpensive, and quantitative detection of •OH for conducting informed explorations of its role in mediated oxidation processes at electrode surfaces for energy, environmental, and synthetic applications.