H2O2 Consumption Research Articles

The mechanisms of alteration of a homogeneous U0.73Pu0.27O2 MOx fuel under alpha radiolysis of water

An homogeneous MOx fuel with 24 wt% of plutonium was leached in a carbonated water (10−2 M) under argon ([O2] < 1 vppm) for one year in order to assess the leaching behaviour of U–Pu oxide solid solutions and more specifically to simulate the behaviour of Pu enriched agglomerates characteristic of heterogeneous Mimas MOx fuel. The alpha activity of the pellets was 2.2 × 109 Bq. g−1. Two successive dissolution regimes were observed: an initial dissolution with a uranium release rate of 1.2 × 10−4 molU.m−2. d−1, and then, a long-term dissolution regime with a rate of 7.6 × 10−6 molU.m−2. d−1. The H2O2 concentration was under the detection limit of 1 × 10−7 mol L−1. Pu concentration in the homogeneous solution was constant around 10−9 mol L−1 throughout the duration of the experiment, in accordance with a thermodynamic equilibrium controlled by an amorphous Pu(OH)4 phase. SEM – WDS analysis confirmed a Pu-enriched layer at the surface of the pellets with Pu contents up to 39 wt%. This Pu-enriched layer becomes more resistant against leaching than the pristine surface. Despite this Pu enrichment, H2O2 concentration remained very low in the homogeneous solution. Different mechanisms of consumption can be considered, such as the oxidative dissolution of the pellet, the precipitation of U or Pu peroxides or the catalytic disproportionation. As the precipitation of peroxides at the surface was discarded by Raman spectroscopy and the oxidative dissolution was very limited, the low H2O2 concentration was likely due to a higher catalytic disproportionation of H2O2 by the Pu-enriched layer. Mass balance calculation showed that H2O2 disproportionation represented 99% of the H2O2 consumption for the homogeneous MOx, against 86% for UO2 pellets. These results shed new light on the Pu stabilizing mechanisms against the oxidative dissolution that can be applied to model the behaviour of different MOx fuels under long-term disposal conditions.

An ultrasensitive sensing platform for microRNA-155 based on H2O2 quenched hydroxide-dependent ECL emission of PFO Pdots

A strong hydroxide (OH−)-dependent ECL emission of carboxyl functionalized-poly (9,9-di-n-octylfluorenyl-2,7-diyl) polymer dots (PFO Pdots) was observed at +1.25 V, which is significantly stronger than the emission at +1.95 V reported in previous work. Moreover, hydrogen peroxide (H2O2) can efficiently quench OH−-dependent ECL emission of PFO Pdots. Based on this discovery, a signal “off-on” ECL biosensing platform for microRNA-155 (miRNA-155) was developed. Firstly, PFO Pdots were modified onto the electrode to capture DNA duplex track-locker. In the presence of H2O2 in the test solution, the ECL signal of PFO Pdots was quenched to obtain a signal-off state. Subsequently, the DNA walker produced through the target miRNA-155-triggered catalytic hairpin assembly (CHA) walked along the DNA duplex track-locker to output amounts of G-rich short chain, forming a hemin/G-quadruplex. With the consumption of H2O2 by hemin/G-quadruplex, the ECL signal would be restored to a signal-on state, thus achieving an ultrasensitive detection of miRNA-155. The detection limit was low as 12.2 aM. Furthermore, our proposed biosensor demonstrated a tremendous selectivity and admirable stability, and exhibited a satisfactory performance for determinating intracellular miRNA-155. The integration of excellent ECL performance of PFO Pdots without any exogenous species or dissolved O2 as co-reactant and a highly efficient quenching effect of H2O2 on such an ECL emission will provide an attractive ECL platform for bioanalysis and clinical diagnosis.

Degradation of xanthate in waters by hydrogen peroxide, fenton and simulated solar photo-fenton processes

This work reports the findings of a preliminary study of oxidative degradation of ethyl xanthate (EX) in aqueous solutions comparing hydrogen peroxide, the Fenton process, and photo-Fenton process driven by simulated solar radiation. Kinetic runs were carried out following a factorial design using a synthetic effluent with initial [EX]=100mg/L. H2O2 was dosed at the stoichiometric amount required for complete mineralization of EX. The variables studied were: initial pH: 5 and 9; [Fe2+]:[H2O2] molar ratio: 0:0 and 1:40; and irradiance: 0 and 30mW/cm2. An initial fast step breaks down more than 90% of the xanthate, forming intermediates that still contain unoxidized carbon and sulphur. Additional steps occur in which organic carbon and reduced sulphur from the intermediates may ultimately be converted into bicarbonate and sulphate. The progress of the reaction is indicated by reduction in TOC, gain in sulphate (SO4), and H2O2 consumption. Overall the optimum conditions for the breakdown of EX were those using the photo-Fenton process: initial pH=5; [Fe2+]:[H2O2] molar ratio=1:40; and irradiance=30mW/cm2. After 2h the best results were: xanthate breakdown=98.6%; TOC reduction=39.2%; SO4 generation=43.1%. The experiments were conducted batchwise and this led to partial mineralization of the xanthate's organic and sulphur contents. The statistical design using simulated solar radiation enabled us to conclude that tailings ponds could be used as treatment reactors, where their efficiency is enhanced by sunlight.

The liquid fraction from hydrothermal pretreatment of wheat straw provides lytic polysaccharide monooxygenases with both electrons and H2O2 co-substrate

BackgroundEnzyme-aided valorization of lignocellulose represents a green and sustainable alternative to the traditional chemical industry. The recently discovered lytic polysaccharide monooxygenases (LPMOs) are important components of the state-of-the art enzyme cocktails for cellulose conversion. Yet, these monocopper enzymes are poorly characterized in terms of their kinetics, as exemplified by the growing evidence for that H2O2 may be a more efficient co-substrate for LPMOs than O2. LPMOs need external electron donors and one key question of relevance for bioprocess development is whether the required reducing power may be provided by the lignocellulosic substrate.ResultsHere, we show that the liquid fraction (LF) resulting from hydrothermal pretreatment of wheat straw supports LPMO activity on both chitin and cellulose. The initial, transient activity burst of the LPMO reaction was caused by the H2O2 present in the LF before addition of LPMO, while the steady-state rate of LPMO reaction was limited by the LPMO-independent production of H2O2 in the LF. H2O2 is an intermediate of LF oxidation as evidenced by a slow H2O2 accumulation in LF, despite high H2O2 production rates. This H2O2 scavenging ability of LF is important since high concentrations of H2O2 may lead to irreversible inactivation of LPMOs.ConclusionsOur results support the growing understanding that fine-tuned control over the rates of H2O2 production and consumption in different, enzymatic and non-enzymatic reactions is essential for harnessing the full catalytic potential of LPMOs in lignocellulose valorization.

ATP Mimics pH-Dependent Dual Peroxidase-Catalase Activities Driving H 2 O 2 Decomposition

Adenosine triphosphate (ATP) is produced mainly in the mitochondrion, and its primary task is to function as a ubiquitous energy currency to meet the cellular metabolic demands in biological system...

Nitrogen moieties -dominated Co–N-doped nanoparticle-modified cathodes in heterogeneous-electro-Fenton-like system for catalytic decontamination of EDTA-Ni(II)

Ethylenediaminetetraacetic acid (EDTA) could form stable complexes with toxic metals such as nickel due to its strong chelation. In this study, with the same doping level of Co and N, MoO2 and ZIF-67 were used as precursors to prepare MoO2@Co/N and FeC@Co/N electrocatalysts for the modified graphite felt cathodes in heterogeneous-electro-Fenton-like reaction (HEFL) system. The X-ray diffraction and X-ray photoelectron spectroscopy results indicated that both of the catalysts are dominated with pyridinic N (2.42% and 2.82%) upon co-doping Co/N, and FeC@Co/N exhibited an obviously higher additional sp-hybridized nitrogen (sp-N) peak. The co-doping of Co/N induced the lattice modifications to produce more lattice defects, where pyridinic N and sp-N, related with the active sites (C–N, Co-Nx), were formed at near-ring defects along sheet edges through the nitrogen replacement of CC groups. FeC@Co/N demonstrated superior oxygen reduction reaction catalytic activity in terms of Cyclic Voltammetry and Rotating Ring-disk Electrode, and exhibited the remarkably higher current density (30 mA) and lower onset potential (−0.208 V) in Linear Sweep Voltammetry analysis. In the FeC@Co/N/CF modified HEFL system, despite the generated H2O2 concentrations (62.5 mg L−1) is not very high, the reducing reaction of ≡Fe(III)/Co(III)–OH could get the electron directly from the cathode, which would greatly reduce the consumption of H2O2, high utilization efficiency of H2O2 (η: 87.63%) could greatly improve the EDTA-Ni removal (97.5%) and TOC (92.6%). This work demonstrates the feasibility of utilizing FeC@Co/N/CF as a cathode for breaking metal-complex in HEFL process.

The pH effect on the kinetics of 4-nitrophenol removal by CWPO with doped carbon black catalysts

P, B and N-doped carbon blacks prepared with H3PO4, urea and H3BO3 were tested as catalysts in the wet peroxide oxidation of a concentrated 4-nitrophenol (4-NP) model solution (C4-NP = 5 g·L−1). The highest catalytic activity was found for P-doped carbon black (complete removal of 4-NP after 4 h at 80 °C, Ccat = 2.5 g·L−1, CH2O2=17.8 g·L−1 and initial pH 3, whereas 44-19% removals were reached with the other catalysts). That was ascribed to the strongest acidity (pHPZC = 3.5) and hydrophilic character of the catalyst. Initial pH affected the oxidation, allowing to increase strongly the conversion of 4-NP with the P-doped catalyst decreasing the initial pH from 4 to 2 (4-NP removal from 20% to 99% after 8 h of reaction time at 50 °C, Ccat = 2.5 g·L−1 andCH2O2=17.8 g·L−1). An autocatalytic-power-law kinetic model was developed to predict the observed induction period and the dependence on the pH of the 4-NP oxidation, H2O2 consumption and pH evolution (k4-NP = 2.2·10−5 M−2 min−1, kH2O2=4.0·10−6 M−3·min−1 and kH+=5.1·10−3 M−0.23 min−1 at 80 °C).

Effects of bioenergetics, temperature and cadmium on liver mitochondria reactive oxygen species production and consumption

A by-product of mitochondrial substrate oxidation and electron transfer to generate cellular energy (ATP) is reactive oxygen species (ROS). Superoxide anion radical and hydrogen peroxide (H2O2) are the proximal ROS produced by the mitochondria. Because low levels of ROS serve critical regulatory roles in cell physiology while excessive levels or inappropriately localized ROS result in aberrant physiological states, mitochondrial ROS need to be tightly regulated. While it is known that regulation of mitochondrial ROS involves balancing the rates of production and removal, the effects of stressors on these processes remain largely unknown. To illuminate how stressors modulate mitochondrial ROS homeostasis, we investigated the effects of temperature and cadmium (Cd) on H2O2 emission and consumption in rainbow trout liver mitochondria. We show that H2O2 emission rates increase with temperature and Cd exposure. Energizing mitochondria with malate-glutamate or succinate increased the rate of H2O2 emission; however, Cd exposure imposed different patterns of H2O2 emission depending on the concentration and substrate. Specifically, mitochondria respiring on malate-glutamate exhibited a saturable graded concentration-response curve that plateaued at 5 μM while mitochondria respiring on succinate had a biphasic concentration-response curve characterized by a spike in the emission rate at 1 μM Cd followed by gradual diminution at higher Cd concentrations. To explain the observed substrate- and concentration-dependent effects of Cd, we sequestered specific mitochondrial ROS-emitting sites using blockers of electron transfer and then tested the effect of the metal. The results indicate that the biphasic H2O2 emission response imposed by succinate is due to site IIF but is further modified at sites IQ and IIIQo. Moreover, the saturable graded H2O2 emission response in mitochondria energized with malate-glutamate is consistent with effect of Cd on site IF. Additionally, Cd and temperature acted cooperatively to increase mitochondrial H2O2 emission suggesting that increased toxicity of Cd at high temperature may be due to increased oxidative insult. Surprisingly, despite their clear stimulatory effect on H2O2 emission, Cd, temperature and bioenergetic status did not affect the kinetics of mitochondrial H2O2 consumption; the rate constants and half-lives for all the conditions tested were similar. Overall, our study indicates that the production processes of rainbow trout liver mitochondrial H2O2 metabolism are highly responsive to stressors and bioenergetics while the consumption processes are recalcitrant. The latter denotes the presence of a robust H2O2 scavenging system in liver mitochondria that would maintain H2O2 homeostasis in the face of increased production and reduced scavenging capacity.

EPR spin trapping studies of H2O2 activation in metaloporphyrin catalyzed oxygenation reactions: Insights on the biomimetic mechanism

Oxygen radicals have been proposed to have a role in the metaloporphyrin based biomimetic mechanisms as they can be formed from metal-oxo or metal-hydroperoxy species. Herein EPR studies of biomimetic oxygenation reactions using BMPO as a spin trap are used to investigate the production of reactive oxygen species during the catalytic activation of H2O2 by FeIII and MnIII porphyrins. Firstly, reactions in control conditions were studied and the formation of BMPO-OH• adducts was observed. These provided a baseline system for further comparative evaluation of the effect of different components of the catalytic reactions, including metaloporphyrins, solvents, co-catalysts and substrates on ROS production and H2O2 consumption. In the absence of co-catalyst or using ammonium acetate as co-catalyst, the metaloporphyrin centered pathways do not generate additional hydroxyl or superoxide radicals. In contrast, in the presence of sodium hydroxide, the production of additional hydroxyl radicals by a metaloporphyrin-mediated process is observed. The EPR results also differentiate the action of intermediates ascribed to metaloporphyrin-H2O2 adducts and high-valent oxo-species by their relative rates of H2O2 consumption and their effect on the production of BMPO-OH•.

Treatment of high-strength olive mill wastewater by combined Fenton-like oxidation and coagulation/flocculation

The efficiency of Fenton/Fenton-like processes on the oxidation of organic matter from real olive mill wastewater (OMW) is described. Tests were performed in lab-scale batch reactors and the influence of different operational parameters was evaluated, namely: type of iron salt, effect of pH readjustments during the reaction, reactants addition method and Fe/H2O2 mass ratio. For the Fenton-like system (Fe3+/H2O2) it was found that H2O2 consumption and consequently total organic carbon (TOC) degradation rate are significantly affected by the reagents addition method, especially in earlier stages of the reaction, although the overall extent of TOC removal is not. Results showed that the gradual addition of H2O2 along with pH readjustments during the process led to better chemical oxygen demand (COD) and total phenolic content (TPh) reduction. Operating at pH0 = 3.0, T0 = 25 °C, [Fe3+] = 1.0 g·L−1 and Fe/H2O2 = 0.04, 34.9% of TOC, 55.7% of COD and 81.4% of TPh were removed after 180 min. The same conditions were applied with the assistance of artificial radiation (photo-Fenton-like process) with slight organic matter degradation improvement (41.8% of TOC, 63.2% of COD and 83.8% of TPh removals). The catalyst’s (ferric chloride salt) ability to act as a coagulant/flocculant after the oxidative process was also checked, being reached a global reduction of 76.7% for COD and 96.4% for TPh after 1 h of sedimentation and no further pH adjustments. Moreover, the effluent’s biodegradability (BOD5:COD ratio) after the combined process improved from the initial value of 0.11 to 0.33, and toxicity against the bioluminescent Vibrio fischeri bacteria decreased from 53% to 4%, putting into evidence the possibility of coupling downstream a biological unit so that the final effluent meets legal discharge limits.

Degradation of Nystatin in aqueous medium by coupling UV-C irradiation, H2O2 photolysis, and photo-Fenton processes.

Oxidative degradation and mineralization of the antifungal drug Nystatin (NYS) was investigated using photochemical advanced oxidation processes UV-C irradiation (280-100nm), H2O2 photolysis (UV/H2O2), and photo-Fenton (UV/H2O2/Fe3+). The effect of operating parameters such as [H2O2], [Fe3+], and [NYS] initial concentrations on degradation efficiency and mineralization ability of different processes was comparatively examined in order to optimize the processes. Photo-Fenton was found to be the most efficient process attaining complete degradation of 0.02mM (19.2mgL-1) NYS at 2min and a quasi-complete mineralization (97%) of its solution at 5h treatment while UV/H2O2 and UV-C systems require significantly more time for complete degradation and lower mineralization degrees. The degradation and mineralization kinetics were affected by H2O2 and Fe3+ initial concentration, the optimum dosages being 4mM and 0.4mM, respectively. Consumption of H2O2 during photo-Fenton treatment is very fast during the first 30min leading to the appearance of two stages in the mineralization. The evolution of toxicity of treated solutions was assessed and confirmed the effectiveness of photo-Fenton process for the detoxification of NYS solution at the end of treatment. Application to real wastewater from pharmaceutical industry containing the target molecule NYS showed the effectiveness of photo-Fenton process since it achieved 92% TOC removal rate at 6-h treatment time.

Studies on decomposition behavior of oxalic acid waste by UVC photo-Fenton advanced oxidation process

Abstract A UVC photo-Fenton advanced oxidation process (AOP) was studied to develop a process for the decomposition of oxalic acid waste generated in the chemical decontamination of nuclear power plants. The oxalate decomposition behavior was investigated by using a UVC photo-Fenton reactor system with a recirculation tank. The effects of the three operational variables―UVC irradiation, H2O2 and Fenton reagent―on the oxalate decomposition behavior were experimentally studied, and the behavior of the decomposition product, CO2, was observed. UVC irradiation of oxalate resulted in vigorous CO2 bubbling, and the irradiation dose was thought to be a rate-determining variable. Based on the above results, the oxalate decomposition kinetics were investigated from the viewpoint of radical formation, propagation, and termination reactions. The proposed UVC irradiation density model, expressed by the first-order reaction of oxalate with the same amount of H2O2 consumption, satisfactorily predicted the oxalate decomposition behavior, irrespective of the circulate rate in the reactor system within the experimental range.

Morphology control of c-Si via facile copper-assisted chemical etching: Managements on etch end-points

Abstract Micro-/nano-structures enable crystalline silicon (c-Si) to be prominent in many fields. In this work, an elaborate study on texturing c-Si via copper-assisted chemical etching (Cu-ACE) is reported. Various large-area craters arrays including gyro-like craters arrays, standard inverted pyramids arrays and deformed inverted pyramids arrays, together with mesoporous surfaces and polished-like surfaces are synthesized on Si wafers with Cu-ACE. An electrokinetic “H2O2 consumption” model and an energy band model are proposed to explain the synergetic effects between isotropic and anisotropic etching on preparing Si micro-/nano-structures during etching. It is demonstrated that the etched morphology is determined by the temporal H2O2 relative concentration at etch end-points, which is accurately controlled by etching conditions. A “curved sidewalls” model is put forward, for the first time, to illustrate the nuances among etched craters arrays. Based on this model, the local H2O2 relative concentration determines local curvatures of sidewalls. Textured Si wafers with inverted pyramids arrays exhibit excellent anti-reflection abilities and are promising for solar cells, photodiodes or other optoelectronic applications. Notably, our work provides a facile and controllable approach to produce various Si micro-/nano-structures which are of practical values in many domains.

Long-lasting activity of Fe0-C internal microelectrolysis-Fenton system assisted by Fe@C-montmorillonites nanocomposites

Core/shell type Fe0@carbon (Fe@C) nanocomposites inserted in the interlayer space of montmorillonites (MMT) is prepared by one-step pyrolysis of Fe-metal organic frameworks and MMT. Fe@C-MMT serves as Fenton-like catalyst to degrade organic pollutants based on internal microelectrolysis (IME)-Fenton reactions. The MMT coat accelerates galvanic corrosion of Fe0 to facilitate in-situ generation of Fe2+ and achieves self-regulation of solution pH. Strengthened elimination of phenol and methyl orange with high mineralization efficiency (80%) at initial pH 3–6.5 was achieved in Fe@C-MMT-H2O2 system compared to Fe@C-, ZVI-, and commercial Fe-C-H2O2 systems. The MMT coat retards contact of Fe0 and Fe(II) species on Fe@C-MMT surface with H2O2, leading to rate-controlling consumption of H2O2 to keep the long-lasting efficiency of the IME-Fenton system. Fe@C-MMT suspension with 10 mM of H2O2 can continuously degrade organic pollutants within 40 h. Fe@C-MMT can be recycled for five times and shows good resistance to oxygen and acid corrosion.

The effect of n-3 long-chain polyunsaturated fatty acids and lipoic acid on the heart in the ovariectomized rat model of menopause

Menopause occurs as consequence of ovarian senescence that leads to a drop of oestrogen hormone. The decreased oestrogen levels combined with the impairment of the redox system may contribute to the increased risk of postmenopausal cardiovascular disease. Supplementation with antioxidants may be an alternative to reduce cardiovascular risk. The study evaluated the effect of dietary supplementation with docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and α-lipoic acid (LA) for a period of 16 weeks on oxidative stress biomarkers in the hearts of ovariectomized 3-month-old rats. Ovariectomy did not increase the level of the damage markers malondialdehyde and carbonyl, and both were decreased by LA supplementation. Ovariectomy increased the levels of the endogenous antioxidants glutathione, vitamin C and H2O2 consumption, after restoration by DHA, EPA, and LA supplementation. Vitamin E, glutathione peroxidase, glutathione-S-transferase, and superoxide dismutase are not altered by ovariectomy. Lipid and protein damage are not increased after ovariectomy and a portion of the endogenous antioxidants concomitantly increased, suggesting that hearts may be protected by these antioxidants. DHA, EPA, and LA restored these endogenous antioxidants, showing that all evaluated supplements are effective in modulating the antioxidant redox system in the heart. LA showed additional effect on redox markers, decreasing lipid and protein damage markers.

Efficient degradation of cefotaxime by a UV+ferrihydrite/TiO2+H2O2 process: the important role of ferrihydrite in transferring photo‐generated electrons from TiO2 to H2O2

AbstractBackgroundDeveloping effective removal processes for antibiotics has attracted increasing interest recently. In this work, a novel strategy involving the combination of photocatalysis with Fenton reaction using ferrihydrite/TiO2 (Fh/TiO2) nanohybrids was developed to efficiently degrade the antibiotic cefotaxime. Fh/TiO2 nanohybrids were synthesized by simply growing Fh on the surface of commercially available TiO2. We expected that Fh of Fh/TiO2 could capture photo‐generated electrons from TiO2, inhibiting the recombination of electron–hole pairs; also, by virtue of Fe(III)/Fe(II) cycle on Fh/TiO2, photo‐generated electrons could be continually transferred to H2O2 to produce ·OH. Accordingly, high degradation efficiency of cefotaxime could be achieved.ResultsWith UV light and H2O2, Fh/TiO2 with a Fe/Ti molar radio of 7% showed high catalytic activity indeed, and its degradation rate for cefotaxime was nearly three times higher than that of TiO2. The decomposition of H2O2 and production of ·OH in the UV+7%Fh/TiO2+H2O2 system were also increased markedly. The large amount of Fe(II) on 7%Fh/TiO2 determined in this system supported our hypothesis that Fh of 7%Fh/TiO2 could capture photo‐generated electrons from TiO2. Although dissolved iron was observed, the contribution of Fenton reaction by dissolved iron was rather limited. After four consecutive cycles, 7%Fh/TiO2 still retained good stability.ConclusionsThe UV+7%Fh/TiO2+H2O2 system provides a potential alternative in degradation of cefotaxime for further practical application, and it has the following advantages: high catalytic activity, simple preparation method, good stability and low cost, as well as continued catalytic activity after total consumption of H2O2. © 2019 Society of Chemical Industry

Effect of dexmedetomidine on ischemia-reperfusion injury of liver and kidney tissues in experimental diabetes and hepatic ischemia-reperfusion injury induced rats

Background: Reperfusion following ischemia can lead to more injuries than ischemia itself especially in diabetic patients. The aim of this study was to evaluate the effect of dexmedetomidine on ischemia-reperfusion injury (IRI) in rats with have hepatic IRI and diabetes mellitus.

Investigation of Cell Microenvironment Effect on Cell Behaviors Using Electrochemical Scanning Probe Microscopy

Cell microenvironment (chemical, mechanical, electric) directly effects cell functions and behaviors (biology, mechanics, electrophysiology). Study of cell microenvironment effect on cell functions and behaviors is important for understanding the pathological mechanism of diseases (heart disease, cancer). Different kinds of hydrogels, which is an ideal material to mimic 3D extracellular matrix (ECM) of cell, have been developed and used to construct 3D cell microenvironment in vitro. To understand the effect of cell microenvironment constructed by hydrogels on cell behaviors, the technique which can characterize both the property of hydrogels and the topography and multi-behaviors of cells at mm/nm scale in an in-situ, non-damage way is needed. Scanning electrochemical microscopy (SECM) and scanning ion conductance microscopy (SICM) are two kinds of electrochemical scanning probe microscopy with the capability of providing morphology and performing chemical analyses of cells in an in situ, reversible and non-destructive way. In our work, we firstly constructed cell microenvironment based on three kinds of functional hydrogels (i.e., self-healing hydrogels, magnetic hydrogels and hydrogel microwell arrays). Then SECM was applied to in-situ track the self-healing process of hydrogel, the H2O2 consumption across magnetic hydrogel nanocomposites and the oxygen permeability across hydrogel microwell arrays. The effect of mechanical microenvironment on the redox state of cardiomyocytes and cardiac fibroblasts was also characterized by SECM. To further characterize the cell morphology at nm-scale, we also home built our SICM system and used it to characterize the cell morphology and cell volume on hydrogels with different stuffiness. Figure 1

Glucosamine Phosphate Induces AuNPs Aggregation and Fusion into Easily Functionalizable Nanowires.

The challenge to obtain plasmonic nanosystems absorbing light in the near infrared is always open because of the interest that such systems pose in applications such as nanotherapy or nanodiagnostics. Here we describe the synthesis in an aqueous solution devoid of any surfactant of Au-nanowires of controlled length and reasonably narrow dimensional distribution starting from Au-nanoparticles by taking advantage of the properties of glucosamine phosphate under aerobic conditions and substoichiometric nanoparticle passivation. Oxygen is required to enable the process where glucosamine phosphate is oxidized to glucosaminic acid phosphate and H2O2 is produced. The process leading to the nanosystems comprises nanoparticles growth, their aggregation into necklace-like aggregates, and final fusion into nanowires. The fusion requires the consumption of H2O2. The nanowires can be passivated with an organic thiol, lyophilized, and resuspended in water without losing their dimensional and optical properties. The position of the broad surface plasmon band of the nanowires can be tuned from 630 to >1350 nm.

Visual distance readout to display the level of energy generation in paper-based biofuel cells: application to enzymatic sensing of glucose.

Biofuel cells (BFCs) based on anodic oxidation and cathodic oxygen reduction represent an attractive alternative to self-powered devices. A glucose/oxygen BFC is described for monitoring glucose. It is making use of a piece of paper carrying a glucose oxidase (GOx) based bioanode, and a bilirubin oxidase (BilOx) based biocathode. The performance of the BFC is affected by the generation of H2O2, a byproduct of enzymatic glucose oxidation. Therefore, the removal of H2O2 is a crucial step in terms of BFC performance and stability. In addition, direct, unambiguous visual read-out is an ideal way to provide quantitative information. The colorimetric readout system described here is based on the consumption of undesired H2O2 and to convert the extent of energy generation into recognizable variations in color. As the H2O2 travels along the hydrophilic channel by capillary action, the formation of red gold nanoparticles from AuCl4- leads to the appearance of a red bar that provides distance-based information that can be read visually. The multiply readable information (maximum power density of BFC or visible distance) provides further choices for quantification. It also enhances reliability. The self-powered system based on the BFC exhibits excellent performance. Glucose can bedetermined by this method in the 1 to 50mM concentration range. Graphical abstract Schematic presentation of a paper-supported biofuel cell equipped with a visual distance readout to display the level of energy generation in biofuel cells, andits application in sensing of glucose.