Fluorescence detection of hydroxyl radicals

Newton, Gerald L.; Milligan, Jamie R.

doi:10.1016/j.radphyschem.2005.10.011

Cited by 120 publications

(97 citation statements)

References 24 publications

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“…'s experimental setup involved placing a solution of the fluorescence agent adjacent to the fuel cell electrodes, where they monitored the fluorescence of this solution ex situ. There are many reports from the chemical biology literature that describe the use of fluorescence spectroscopy to indirectly monitor ROS (25)(26)(27)(28)(29)(30)(31). In this paper, we improve upon on Nosaka, et.al.…”

mentioning

confidence: 99%

“…However, these measurements are limited to cells that fit within the EPR probe and cannot be translated to subscale or larger scale cells operating under realistic conditions. Nosaka and coworkers reported the indirect measurement of ROS generation rates using fluorescence spectroscopy, where a fluorescent molecular probe, coumarin, was incorporated into the fuel cell and the probe was shown to be sensitive to ROS (25). Nosaka, et.al.…”

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confidence: 99%

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Investigation of polymer electrolyte membrane chemical degradation and degradation mitigation using in situ fluorescence spectroscopy

Prabhakaran

Arges

Ramani

2012

Proc. Natl. Acad. Sci. U.S.A.

139

126

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A fluorescent molecular probe, 6-carboxy fluorescein, was used in conjunction with in situ fluorescence spectroscopy to facilitate realtime monitoring of degradation inducing reactive oxygen species within the polymer electrolyte membrane (PEM) of an operating PEM fuel cell. The key requirements of suitable molecular probes for in situ monitoring of ROS are presented. The utility of using free radical scavengers such as CeO 2 nanoparticles to mitigate reactive oxygen species induced PEM degradation was demonstrated. The addition of CeO 2 to uncatalyzed membranes resulted in close to 100% capture of ROS generated in situ within the PEM for a period of about 7 h and the incorporation of CeO 2 into the catalyzed membrane provided an eightfold reduction in ROS generation rate.fuel cells | Nafion® degradation | hydroxyl radicals | hydroperoxyl radicals | miniature fluorescence probe H ydrogen/air (H 2 ∕air) polymer electrolyte membrane (PEM) fuel cells possess high efficiency and modularity. However, significant technical advances are required to facilitate fuel cells' commercialization and widespread use in targeted applications in the automotive, portable power, and military sectors. A key technological issue that remains to be addressed is component durability under an array of adverse operating conditions. The ionexchange membrane in a PEM fuel cell is one of the components whose limited long-term durability is of concern. The PEM undergoes mechanical, thermal, and chemical degradation during fuel cell operation (1-8). The chemical degradation process that takes place in a H 2 ∕O 2 PEM fuel cell is attributed to reactive oxygen species (ROS) that are generated in situ through both chemical and electrochemical pathways during fuel cell operation. Hydrogen peroxide (H 2 O 2 ) is an ROS and is often an intermediate formed in both pathways and is known to form free radical ROS in the presence of transition metal ions via the Fenton mechanism (9-12). These free radical ROS, namely hydroxyl and hydroperoxyl radicals, are amongst the strongest oxidizing agents known. ROS initiate oxidative degradation of both the PEM backbone and the side chains that contain ionic groups that are essential for ion conduction (13-16). The adverse consequences of these degradation modes (e.g., membrane thinning, pin-hole formation, and loss of ionic conductivity) eventually contribute to catastrophic cell and stack failure. Complete elimination of ROS generation and PEM chemical degradation, while a worthy goal, is difficult due to constraints in terms of membrane materials, choice of fuel and oxidant, and fuel cell operating conditions. Therefore, it is imperative to develop effective mitigation strategies that minimize the rate and extent of PEM degradation.Prior to proposing an effective mitigation strategy, it is essential to quantify the rate of ROS generation within the PEM during fuel cell operation. However, detecting the presence of ROS within the PEM of an operating fuel cell is an extremely difficult proposition because free ra...

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confidence: 99%

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confidence: 99%

Investigation of polymer electrolyte membrane chemical degradation and degradation mitigation using in situ fluorescence spectroscopy

Prabhakaran

Arges

Ramani

2012

Proc. Natl. Acad. Sci. U.S.A.

139

126

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“…Since the photocatalytic reaction occurs on the surface of the particles, the particles with the high surface area exhibited higher photocatalytic activity due to the increase in the interaction between the TPA molecules and surface of the particles. Another important factor affecting the photocatalytic activity of the catalyst is the hydroxyl radicals ( Á OH) produced during the photocatalysis [43][44][45][46]. The difference in the formation rates of Á OH on the catalyst surface based on the properties of the catalyst may cause this photocatalytic variance.…”

Section: Photocatalytic Activitymentioning

confidence: 99%

Visible light photocatalytic activity of rutile TiO2 fiber clusters in the degradation of terephthalic acid

Yener

Helvacı

2015

Appl. Phys. A

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Rutile TiO 2 nanoparticles, in different structural and morphological properties, were produced by the hydrolysis of titanium tetrachloride in a highly acidic reaction media at moderate temperatures without calcination. Their photocatalytic activities were investigated in the liquid-phase degradation of terephthalic acid under visible light illumination. The parameters, which are the concentration of the titanium tetrachloride solution (0.1-1 M) and reaction temperature (60-95°C), effective on the properties of the particles, and their photocatalytic performances, were investigated. The XRD patterns indicated a pure rutile crystal structure at moderate temperatures without need of calcination. The FEGSEM images showed the formation of flower-, pinecone-, and sphere-like clusters consisting of interconnected nanofibers. The N 2 adsorption-desorption isotherms pointed out the microporous structure of the clusters. Band gap energies were found to be varying between 3.02 and 3.08 eV due to the well-developed rutile crystallite structure. Systematic studies elucidated that the optimum reactant concentration and reaction temperature are 0.5 M TiCl 4 and 95°C, respectively. The rutile clusters synthesized at the optimum reaction conditions exhibited 99 % of the photocatalytic degradation of TPA under visible light illumination at shorter irradiation times compared with commercial P25 TiO 2 .

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“…[13] Their potential use as fluorescent probes has been mainly prevented by low water solubility and the absence of a general methodology for the production of diversely substituted phenoxazinone scaffolds. [14] Recently, our group reported a novel synthetic approach, based on the use of laccase as a biocatalyst, which showed promising results for the "green" production of phenoxazinone dyes featuring variable water solubility.…”

Section: Introductionmentioning

confidence: 99%

Live‐Cell Imaging with Water‐Soluble Aminophenoxazinone Dyes Synthesised through Laccase Biocatalysis

et al. 2010

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Aminophenoxazinone dyes with variable water solubilities were assayed for the first time in a live-cell imaging application. Among a library of ten sulfonylated chromophores, one compound gave excellent results as an endocytic marker, showing a precise subcellular distribution. The compound was compared to four commercial vital tracers, including Lucifer Yellow. The first laccase-mediated regioselective synthesis of a diphosphorylated 2-aminophenoxazinone dye was also described. This compound, water-soluble at 10(-2) M, displayed modest fluorescence properties and the ability to complex Mg(2+) and Ca(2+) cations, therefore giving fluorescence quenching.

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Fluorescence detection of hydroxyl radicals

Cited by 120 publications

References 24 publications

Investigation of polymer electrolyte membrane chemical degradation and degradation mitigation using in situ fluorescence spectroscopy

Investigation of polymer electrolyte membrane chemical degradation and degradation mitigation using in situ fluorescence spectroscopy

Visible light photocatalytic activity of rutile TiO2 fiber clusters in the degradation of terephthalic acid

Live‐Cell Imaging with Water‐Soluble Aminophenoxazinone Dyes Synthesised through Laccase Biocatalysis

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