L-Dehydroascorbate efficiently degrades non-thermal plasma-induced hydrogen peroxide

Improving both performance and stability of n-type organic semiconductors by vitamin C

Organic semiconductors (OSCs) are one of the most promising candidates for flexible, wearable and large-area electronics. However, the development of n-type OSCs has been severely held back due to the poor stability of their most candidates, that is, the intrinsically high reactivity of negatively charged polarons to oxygen and water. Here we demonstrate a general strategy based on vitamin C to stabilize n-type OSCs, remarkably improving the performance and stability of their device, for example, organic field-effect transistors. Vitamin C scavenges reactive oxygen species and inhibits their generation by sacrificial oxidation and non-sacrificial triplet quenching in a cascade process, which not only lastingly prevents molecular structure from oxidation damage but also passivates the latent electron traps to stabilize electron transport. This study presents a way to overcome the long-standing stability problem of n-type OSCs and devices.

Efficient destruction of basic organo-nitrogenous compounds in liquid hydrocarbon fuel using ascorbic acid/H2O2 system under ambient condition

Due to the limitations of the conventional refinery methods, development of a new method such as oxidative denitrogenation (ODN) is highly desirable. This study described a novel ODN to remove organo-nitrogenous compounds (ONCs) in liquid fuel by ascorbic acid (AscH2) and H2O2 redox system under ambient conditions. Seven ONCs including pyridine, quinoline, acridine, 7,8-benzoquinoline, indole, N-methylpyrrolidone (NMP), and N,N-dimethylformamide (DMF) were chosen to assess the fuel-denitrified ability of the AscH2/H2O2 system. The results showed that the basic group of ONCs (pyridine, quinoline, and acridine) can be effectively removed (removal ratio > 95 %) while the removal efficiency of water-soluble compounds (7,8-benzoquinoline, NMP, and DMF) was moderate (61-68 %) under a mild temperature (30 °C) and atmospheric pressure. Free radical quenching and electron paramagnetic resonance experiments confirmed that hydroxyl and AscH2 radicals played a major role in the degradation of ONCs. The degraded products of quinoline were analyzed by gas chromatography-mass spectroscopy and ion chromatography. Based on the identified intermediate products, a putative reaction pathway majorly involving three steps of N-onium formation, transfer hydrogenation, and free radical oxidative ring-opening was suggested for the quinoline degradation. The presented approach can be performed at a normal temperature and pressure and will live up to expectations in the pre-denitrogenation and selective removal of basic ONCs in fuel oils.

The Regulatory Mechanism of Cold Plasma in Relation to Cell Activity and Its Application in Biomedical and Animal Husbandry Practices

As an innovative technology in biological applications, cold plasma is widely used in oral treatment, tissue regeneration, wound healing, and cancer therapy, etc., because of the adjustable composition and temperature which allow the plasma to react with bio-objects safely. Reactive oxygen species (ROS) produced by cold plasma regulate cell activity in an intensity- and time-dependent manner. A low level of ROS produced by cold plasma treatment within the appropriate intensities and times promotes proliferation of skin-related cells and increases angiogenesis, which aid in the acceleration of the wound healing process, while a high level of ROS produced by cold plasma treatment performed at a high intensity or over a long period of time inhibits the proliferation of endothelial cells, keratinocytes, fibroblasts, and cancer cells. Moreover, cold plasma can regulate stem cell proliferation by changing niche interface and producing nitric oxide directly. However, the molecular mechanism of cold plasma regulating cell activity and its potential application in the field of animal husbandry remain unclear in the literature. Therefore, this paper reviews the effects and possible regulatory mechanisms of cold plasma on the activities of endothelial cells, keratinocytes, fibroblasts, stem cells, and cancer cells to provide a theoretical basis for the application of cold plasma to skin-wound healing and cancer therapy. In addition, cold plasma exposure at a high intensity or an extended time shows excellent performances in killing various microorganisms existing in the environment or on the surface of animal food, and preparing inactivated vaccines, while cold plasma treatment within the appropriate conditions improves chicken growth and reproductive capacity. This paper introduces the potential applications of cold plasma treatment in relation to animal-breeding environments, animal health, their growth and reproduction, and animal food processing and preservation, which are all beneficial to the practice of animal husbandry and guarantee good animal food safety results.

Low-temperature plasma as magic wand to differentiate between the good and the evil

Plasma is the fourth physical state of matter, characterized by an ionized gaseous mixture, after solid, liquid, and gas phases, and contains a wide array of components such as ions, electrons, radicals, and ultraviolet ray. Whereas the sun and thunder are typical natural plasma, recent progress in the electronics enabled the generation of body-temperature plasma, designated as low-temperature plasma (LTP) or non-thermal plasma since the 1990s. LTP has attracted the attention of researchers for possible biological and medical applications. All the living species on earth utilize water as essential media for solvents and molecular transport. Thus, biological application of LTP naturally intervenes water whether LTP is exposed directly or indirectly, where plasma-activated lactate (PAL) is a standard, containing H₂O₂, NO₂^- and other identified molecules. Electron spin resonance and immunohistochemical studies demonstrated that LTP exposure is a handy method to load local oxidative stress. Cancer cells are characterized by persistent self-replication and high cytosolic catalytic Fe(II). Therefore, both direct exposure of LTP and PAL can provide higher damage to cancer cells in comparison to non-tumorous cells, which has been demonstrated in a variety of cancer types. The cell death mode is either apoptosis or ferroptosis, depending on the cancer-type. Thus, LTP and PAL are expected to work as an additional cancer therapy to the established guideline protocols, especially for use in somatic cavities or surgical margins.

Non-thermal plasma elicits ferrous chloride-catalyzed DMPO-OH

Non-thermal plasma (NTP) induces the generation of reactive oxygen species (ROS) and reactive nitrogen species, such as hydroxyl radicals (^•OH), hydrogen peroxide (H₂O₂), singlet oxygen, superoxide, ozone, and nitric oxide, at near-physiological temperatures. These molecules promote blood coagulation, wound healing, disinfection, and selective cancer cell death. Based on these evidences, clinical trials of NTP have been conducted for treating chronic wounds and head and neck cancers. Although clinical applications have progressed, the stoichiometric quantification of NTP-induced ROS remains unclear in the liquid phase in the presence of FeCl₂ or FeCl₃ in combination with biocompatible reducing agents, which may modulate the final biological effects of NTP. In this study, we employed electron paramagnetic resonance spectroscopy to quantify ROS using spin-trapping probe, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and H₂O₂, using luminescent probe in the presence of FeCl₂ or FeCl₃. NTP-induced DMPO-OH levels were elevated 10-100 µM FeCl₂ or 500 and 1000 µM FeCl₃. NTP-induced DMPO-OH with 10 µM FeCl₂ or FeCl₃ was significantly scavenged by ascorbate, α-tocopherol, dithiothreitol, reduced glutathione, or oxidized glutathione, whereas dehydroascorbate was ineffective in 2 mM DMPO. NTP-induced H₂O₂ was significantly degraded by 100 µM FeCl₂ and FeCl₃ in an iron-dependent manner. Meanwhile, decomposition of H₂O₂ by catalase decayed DMPO-OH efficiently in the presence of iron, indicating iron causes DMPO-OH production and degradation simultaneously. These results suggest that NTP-induced DMPO-OH is generated by the H₂O₂-consuming, iron-dependent Fenton reaction and ferryl intermediates. The potential iron-mediated ROS production by NTP is also discussed to clarify the interaction between NTP-induced ROS and biomolecules.

Quenching effects of (-)-Epigallocatechin gallate for singlet oxygen production and its protection against oxidative damage induced by Ce6-mediated photodynamic therapy in vitro

BACKGROUND

Singlet oxygen (¹O₂) is highly reactive to biological components such as lipids, proteins and DNA, which induces oxidative damage to cells and tissues. Natural antioxidants may function as ¹O₂ quencher to prevent ¹O₂ involved photosensitized oxidation in biological system.

METHODS

Time-resolved measurement of ¹O₂ luminescence was employed to evaluate the ¹O₂ quenching abilities of natural antioxidants in air-statured phosphate buffered saline (PBS), including (-)-Epigallocatechin gallate (EGCG), Proanthocyanidins, L-carnosine and Vitamin C. The ¹O₂ quenching effects and rate constant of EGCG were investigated by detecting the absorption, fluorescence and ¹H-NMR spectroscopy and ¹O₂ luminescence decay curves, respectively. In addition, the protective activity of EGCG against ¹O₂ oxidative damage caused by Ce6-mediated photodynamic therapy (PDT) was verified in cells.

RESULTS

EGCG, proanthocyanidins, L-carnosine and Vitamin C efficiently quenched ¹O₂ luminescence at 1270 nm. The triplet-state quenching rate constants of EGCG for Rose Bengal (RB), Chlorin e6, AlPcS and HiPorfin are 2.21 × 10⁹, 4.90 × 10⁸, 3.30 × 10⁸, 1.78 × 10⁹ M^-1s^-1, while the ¹O₂ quenching rate constants are 2.80 × 10⁸, 1.50 × 10⁸, 1.30 × 10⁸, 1.70 × 10⁸ M^-1s^-1, respectively. Furthermore, EGCG could effectively quench ¹O₂ production to prevent NIH/3T3 cells oxidative damage induced by Ce6-mediated PDT.

CONCLUSIONS

EGCG is an efficient quencher for both triplet-state photosensitizers and ¹O₂. The quenching ability of EGCG during photosensitization for selected photosensitizers is: RB > HiPorfin > Ce6 > AlPcS. EGCG could be used to protect normal cells and tissue against oxidative damage.

Non-thermal plasma-induced DMPO-OH yields hydrogen peroxide

Recent developments in electronics have enabled the medical applications of non-thermal plasma (NTP), which elicits reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as hydroxyl radical (●OH), hydrogen peroxide (H2O2), singlet oxygen (1O2), superoxide (O2●-), ozone, and nitric oxide at near-physiological temperatures. In preclinical studies or human clinical trials, NTP promotes blood coagulation, eradication of bacterial, viral and biofilm-related infections, wound healing, and cancer cell death. To elucidate the solution-phase biological effects of NTP in the presence of biocompatible reducing agents, we employed electron paramagnetic resonance (EPR) spectroscopy to quantify ●OH using a spin-trapping probe, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO); 1O2 using a fluorescent probe; and O2●- and H2O2 using luminescent probes in the presence of thiols or tempol. NTP-induced ●OH was significantly scavenged by dithiothreitol (DTT), reduced glutathione (GSH), and oxidized glutathione (GSSG) in 2 or 5 mM DMPO. NTP-induced O2●- was significantly scavenged by 10 μM DTT and GSH, while 1O2 was not efficiently scavenged by these compounds. GSSG degraded H2O2 more effectively than GSH and DTT, suggesting that the disulfide bonds reacted with H2O2. In the presence of 1-50 mM DMPO, NTP-induced H2O2 quantities were unchanged. The inhibitory effect of tempol concentration (50 and 100 μM) on H2O2 production was observed in 1 and 10 mM DMPO, whereas it became ineffective in 50 mM DMPO. Furthermore, DMPO-OH did not interact with tempol. These results suggest that DMPO and tempol react competitively with O2●-. Further studies are warranted to elucidate the interaction between NTP-induced ROS and biomolecules.