High-Field Electron Paramagnetic Resonance and Density Functional Theory Study of Stable Organic Radicals in Lignin: Influence of the Extraction Process, Botanical Origin, and Protonation Reactions on the Radical <b>g</b> Tensor

Bährle, Christian; Nick, Thomas U.; Bennati, Marina; Jeschke, Gunnar; Vogel, Frédéric

doi:10.1021/acs.jpca.5b02200

Cited by 65 publications

(61 citation statements)

References 55 publications

(90 reference statements)

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“…1). All samples provided EPR spectra with a single broad signal, which corresponded well with EPR spectral data reported for similar substrates [24,25]. The spectra (Fig 1.…”

Section: Laccase Catalysed Activation Of Lignin Suspensionssupporting

confidence: 83%

“…The spectra (Fig 1. ) showed no pronounced resolved hyperfine interactions and were slightly asymmetric indicating anisotropic signals as previously reported for lignin derived phenoxyl radicals [24] or that more than one type of radical was formed [26].…”

Section: Laccase Catalysed Activation Of Lignin Suspensionsmentioning

confidence: 51%

“…In general, the EPR spectra of the radicals from the supernatants produced higher gvalues compared to radicals from the corresponding suspensions, but it was most pronounced for the SOL samples ( Table 1). The difference in g-values between radicals in the supernatants and the suspensions may suggest that the distribution of phenoxy radical species was slightly different in the supernatants and in the suspensions of the lignin samples [24].…”

Section: Distribution Of Radicals In Lignin Suspensionsmentioning

confidence: 99%

“…As the presence of different radicals affect the g factor of the EPR spectra, the slightly higher values recorded may be explained by the presence or predominance of other stable radicals such as e.g. semi-quinones known to be present in organosolv lignin [24,28].…”

Section: Laccase Catalysed Activation Of Lignin Suspensionsmentioning

confidence: 99%

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Direct rate assessment of laccase catalysed radical formation in lignin by electron paramagnetic resonance spectroscopy

Munk

Andersen

Meyer

2017

Enzyme and Microbial Technology

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Highlights Time course EPR measurement of direct radical formation by fungal laccases on genuine lignin samples  Assessment of enzyme kinetic rates of radical formation in lignin by two fungal laccases  Identification of different radical formation patterns by a low and high redox potential laccase  Demonstration of different laccase rates on different types of lignin substrates Abstract Laccases (EC 1.10.3.2) catalyse removal of an electron and a proton from phenolic hydroxyl groups, including phenolic hydroxyls in lignins, to form phenoxy radicals during reduction of O2. We employed electron paramagnetic resonance spectroscopy (EPR) for real time measurement of such catalytic radical 2 formation activity on three types of lignin (two types of organosolv lignin, and a lignin rich residue from wheat straw hydrolysis) brought about by two different fungal laccases, derived from Trametes versicolor (Tv) and Myceliophthora thermophila (Mt), respectively. Laccase addition to suspensions of the individual lignin samples produced immediate time and enzyme dose dependent increases in intensity in the EPR signal with g-values in the range 2.0047-2.0050 allowing a direct quantitative monitoring of the radical formation and thus allowed laccase enzyme kinetics assessment on lignin. The experimental data verified that the laccases acted upon the insoluble lignin substrates in the suspensions. When the action on the lignin substrates of the two laccases were compared on equal enzyme dosage levels (by activity units on syringaldazine) the Mt laccase exerted a significantly faster radical formation than the Tv laccase on all three types of lignin substrates. When comparing the equal laccase dose rates on the three lignin substrates the enzymatic radical formation rate on the wheat straw lignin residue was consistently higher than that of the organosolv lignins. The pH-temperature optimum for the radical formation rate in organosolv lignin was determined by response surface methodology to pH 4.8, 33°C and pH 5.8, 33°C for the Tv laccase and the Mt laccase, respectively. The results verify direct radical formation action of fungal laccases on lignin without addition of mediators and the EPR methodology provides a new type of enzyme assay of laccases on lignin.

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“…1). All samples provided EPR spectra with a single broad signal, which corresponded well with EPR spectral data reported for similar substrates [24,25]. The spectra (Fig 1.…”

Section: Laccase Catalysed Activation Of Lignin Suspensionssupporting

confidence: 83%

Section: Laccase Catalysed Activation Of Lignin Suspensionsmentioning

confidence: 51%

Section: Distribution Of Radicals In Lignin Suspensionsmentioning

confidence: 99%

Section: Laccase Catalysed Activation Of Lignin Suspensionsmentioning

confidence: 99%

See 2 more Smart Citations

Direct rate assessment of laccase catalysed radical formation in lignin by electron paramagnetic resonance spectroscopy

Munk

Andersen

Meyer

2017

Enzyme and Microbial Technology

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“…Fine particles, with lower cut-off diameters of 56-320 nm, show a single and unstructured peak with a g factor of ∼ 2.003 and with a peak to peak distance ( H p-p ) ranging from 3 to 8 G. Such spectra are characteristic for EPFR, which have been attributed to semiquinone radicals (Dellinger et al, , 2007Vejerano et al, 2011;Bahrle et al, 2015). Particles with a diameter smaller than 56 nm and larger than 560 nm did not show significant signals, indicating the reduced amount of EPFR in these size ranges.…”

Section: Methodsmentioning

confidence: 99%

Quantification of environmentally persistent free radicals and reactive oxygen species in atmospheric aerosol particles

et al. 2016

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Abstract. Fine particulate matter plays a central role in the adverse health effects of air pollution. Inhalation and deposition of aerosol particles in the respiratory tract can lead to the release of reactive oxygen species (ROS), which may cause oxidative stress. In this study, we have detected and quantified a wide range of particle-associated radicals using electron paramagnetic resonance (EPR) spectroscopy. Ambient particle samples were collected using a cascade impactor at a semi-urban site in central Europe, Mainz, Germany, in May-June 2015. Concentrations of environmentally persistent free radicals (EPFR), most likely semiquinone radicals, were found to be in the range of (1-7) × 10 11 spins µg −1 for particles in the accumulation mode, whereas coarse particles with a diameter larger than 1 µm did not contain substantial amounts of EPFR. Using a spin trapping technique followed by deconvolution of EPR spectra, we have also characterized and quantified ROS, including OH, superoxide (O − 2 ) and carbon-and oxygen-centered organic radicals, which were formed upon extraction of the particle samples in water. Total ROS amounts of (0.1-3) ×10 11 spins µg −1 were released by submicron particle samples and the relative contributions of OH, O − 2 , C-centered and O-centered organic radicals were ∼ 11-31, ∼ 2-8, ∼ 41-72 and ∼ 0-25 %, respectively, depending on particle sizes. OH was the dominant species for coarse particles. Based on comparisons of the EPR spectra of ambient particulate matter with those of mixtures of organic hydroperoxides, quinones and iron ions followed by chemical analysis using liquid chromatography mass spectrometry (LC-MS), we suggest that the particle-associated ROS were formed by decomposition of organic hydroperoxides interacting with transition metal ions and quinones contained in atmospheric humic-like substances (HULIS).

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Lignin Nanosphere‐Modified MXene Activated‐Rapid Gelation of Mechanically Robust, Environmental Adaptive, Highly Conductive Hydrogel for Wearable Sensors Application

Zeng,

Yang,

Pang

et al. 2024

Adv Funct Materials

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Advanced conductive hydrogels demonstrate substantial potential for wearable devices. Nevertheless, the transformative advance in soft electronics raises harsh requirements on the hydrogel candidates, such as rapid and on‐site fabrication, mechanical flexibility, high sensitivity, and wide use temperature. Here, this problem is overcome by incorporating a dual catalytic system based on lignin‐modified MXene‐Fe3+ into commercial hydrogels. This system 1) can form a composite hydrogel in a time scale of min at ambient condition without the supply of external energy, 2) incorporates multiple enhanced strategies into polymer chains, and 3) constructs well‐organized hybrid conductive network. The fabricated hydrogel displays an improved and balanced overall performance, including high ductility (2139%), moderate electrical conductivity, and strong temperature tolerance (−70–50 °C). Combined with the great merits of above performance, the hydrogel‐based sensor with good sensing (maximum GF: 2.8), stable repeatability (200% for 200 cycles), and wide work window of 0%–947%, thereby disclosing promising application in physiological movements, such as motion recognition and breathing state detection. Sensationally, even in complex or harsh surroundings, the sensors also produce stable and reliable signal output. Together, the strategy provides a new mentality of designing hydrogel materials for booming and advanced wearable electronics.

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High-Field Electron Paramagnetic Resonance and Density Functional Theory Study of Stable Organic Radicals in Lignin: Influence of the Extraction Process, Botanical Origin, and Protonation Reactions on the Radical g Tensor

Cited by 65 publications

References 55 publications

Direct rate assessment of laccase catalysed radical formation in lignin by electron paramagnetic resonance spectroscopy

Direct rate assessment of laccase catalysed radical formation in lignin by electron paramagnetic resonance spectroscopy

Quantification of environmentally persistent free radicals and reactive oxygen species in atmospheric aerosol particles

Lignin Nanosphere‐Modified MXene Activated‐Rapid Gelation of Mechanically Robust, Environmental Adaptive, Highly Conductive Hydrogel for Wearable Sensors Application

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