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Ojodomo J Achadu, Tebello Nyokong
Graphitic carbon nitride quantum dots (gCNQDs) when alone or containing embedded 4-amino-2,2,6,6-tetramethyl(piperidin-1-yl)oxyl) (4-AT) (gCNQDs-4-AT(embedded)) were synthesized via low temperature in situ one-pot process from diaminomaleonitrile (DAMN). The blue emission of both gCNQDs and gCNQDs-4-AT were excitation wavelength-dependent with very high fluorescence quantum yields of 43 and 51%, respectively. Further, the gCNQDs were covalently linked to 4-AT via an amide bond to give (gCNQDs-4-AT (linked))...
October 23, 2017: Analytica Chimica Acta
Lijuan Niu, Jian Yu, Weibiao Liao, Jihua Yu, Meiling Zhang, Mohammed M Dawuda
Osmotic stress is a major form of abiotic stress that adversely affects growth and development of plants and subsequently reduces yield and quality of crops. In this study, the effect of nitric oxide (NO) and calcium (Ca(2+)) on the process of adventitious rooting in cucumber (Cucumis sativus L.) under simulated osmotic stress was investigated. The results revealed that the effect of exogenous NO and Ca(2+) in promoting the development of adventitious roots in cucumber seedlings under simulated osmotic stress was dose-dependent, with a maximal biological response at 10 μM NO donor nitroprusside (SNP) or 200 μM Ca(2+)...
2017: Frontiers in Plant Science
Zhuhong Zhang, Zhen Ren, Si Chen, Xiaoqing Guo, Fang Liu, Lei Guo, Nan Mei
4-Methoxy-TEMPO, a derivative of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), is a stable nitroxide radical and is generally used in organic and pharmaceutical syntheses for the oxidation of alcohols. Previously, we reported the involvement of reactive oxygen species (ROS) and c-Jun N-terminal kinases (JNK) in TEMPO-induced apoptosis in mouse L5178Y cells. In this study, we investigated 4-methoxy-TEMPO induced toxicity in human HepG2 hepatoma cells and its underlying mechanisms. Treatments with 4-methoxy-TEMPO (0...
October 9, 2017: Archives of Toxicology
Meng Yang, Jing Xie, Zan Sun, Licun Li, Jean-Pascal Sutter
Ladder-type and chain 2p-3d-4f complexes based on a bridging nitronyl nitroxide radical, namely, [LnCu(hfac)5(NIT-Ph-p-OCH2trz)]·0.5C6H14 [Ln = Y (1a), Dy (1b)] and [LnCu(hfac)5(NIT-Ph-p-OCH2trz)] [Ln = Y (2a), Dy (2b); NIT-Ph-p-OCH2trz = 2-[4-[(1H-1,2,4-triazol-1-yl)methoxy]phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonate) have been successfully achieved through a one-pot reaction of the NIT-Ph-p-OCH2trz radical with Cu(hfac)2 and Ln(hfac)3·2H2O. Complexes 1a and 1b feature a ladder-like structure, where the rails are made of Ln(III) and Cu(II) ions alternatively bridged by nitronyl nitroxide and the triazole units while the NIT-Ph-p-OCH2trz moieties act as the rungs of the ladder...
October 9, 2017: Inorganic Chemistry
Zhanyong Li, Aaron W Peters, Ana E Platero-Prats, Jian Liu, Chung-Wei Kung, Hyunho Noh, Matthew R DeStefano, Neil M Schweitzer, Karena W Chapman, Joseph T Hupp, Omar K Farha
Few-atom cobalt-oxide clusters, when dispersed on a Zr-based metal-organic framework (MOF) NU-1000, have been shown to be active for the oxidative dehydrogenation (ODH) of propane at low temperatures (< 230 °C), affording a selective and stable propene production catalyst. In our current work, a series of promoter ions with varying Lewis acidity, including Ni(II), Zn(II), Al(III), Ti(IV) and Mo(VI), are anchored as metal-oxide,hydroxide clusters to NU-1000 followed by Co(II) ion deposition, yielding a series of NU-1000-supported bimetallic-oxo,hydroxo,aqua clusters...
October 4, 2017: Journal of the American Chemical Society
Zeyu Cao, Xingliang Duan, Ping Yao, Weiti Cui, Dan Cheng, Jing Zhang, Qijiang Jin, Jun Chen, Tianshan Dai, Wenbiao Shen
Metabolism of molecular hydrogen (H₂) in bacteria and algae has been widely studied, and it has attracted increasing attention in the context of animals and plants. However, the role of endogenous H₂ in lateral root (LR) formation is still unclear. Here, our results showed that H₂-induced lateral root formation is a universal event. Naphthalene-1-acetic acid (NAA; the auxin analog) was able to trigger endogenous H₂ production in tomato seedlings, and a contrasting response was observed in the presence of N-1-naphthyphthalamic acid (NPA), an auxin transport inhibitor...
October 3, 2017: International Journal of Molecular Sciences
Kai Zhang, Yuxiang Hu, Lianzhou Wang, Michael J Monteiro, Zhongfan Jia
Nitroxide radical polymers can undergo both excellent electrochemical redox reactions and a rapid "click" coupling reaction with carbon-centered radicals (i.e., nitroxide radical coupling (NRC) reaction). In this work, we report a strategy to functionalize poly(2,2,6,6,-tetramethylpiperidinyl-1-oxyl methacrylate) (PTMA) with pyrene side groups through a rapid and near quantitative NRC reaction. This resulted in P(TMA-co-PyMA) random copolymers with near quantitative amounts of pyrene along the PTMA chain for greater π-π interaction with rGO, while the nitroxide radicals on the polymer could simultaneously be used for energy storage...
October 11, 2017: ACS Applied Materials & Interfaces
Ryunosuke Funahashi, Yusuke Okita, Hiromasa Hondo, Mengchen Zhao, Tsuguyuki Saito, Akira Isogai
Layer-by-layer peeling of surface molecules of native cellulose microfibrils was performed using a repeated sequential process of 2,2,6,6-tetramethylpiperidine-1-oxyl radical-mediated oxidation followed by hot alkali extraction. Both highly crystalline algal and tunicate celluloses and low-crystalline cotton and wood celluloses were investigated. Initially, the C6-hydroxy groups of the outermost surface molecules of each algal cellulose microfibril facing the exterior had the gauche-gauche (gg) conformation, whereas those facing the interior had the gauche-trans (gt) conformation...
October 5, 2017: Biomacromolecules
Elżbieta Megiel
This article provides an overview of the methods for surface modification based on the use of stable radicals: 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its derivatives. Two approaches are discussed. The first relies on the immobilization of TEMPO moieties on the surface of various materials including silicon wafers, silica particles, organic polymers as well as diverse nanomaterials. Applications of such materials with spin labeled surface/interface, in (electro)catalysis, synthesis of novel hybrid nanostructures and nanocomposites as well as in designing of organic magnets and novel energy storage devices are also included in the discussion...
September 20, 2017: Advances in Colloid and Interface Science
Jingchao Li, Jing Zhang, Ying Chen, Naoki Kawazoe, Guoping Chen
Controlling the differentiation of human mesenchymal stem cells (hMSCs) shows a great potential in regenerative medicine. Because overproduced reactive oxygen species (ROS) have an obvious inhibitory effect on the differentiation and functions of hMSCs, it is highly desirable to develop an effective strategy for ROS scavenging and stem cell differentiation controlling. In this study, gold nanoparticles (Au NPs) with an average size of 40 nm were conjugated with 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) to endow them with ROS-scavenging capacity while holding the beneficial effect of Au NPs...
October 18, 2017: ACS Applied Materials & Interfaces
Sang Jun Han, Hong Seok Choi, Jee In Kim, Jeen-Woo Park, Kwon Moo Park
Mitochondrial NADP(+)-dependent isocitrate dehydrogenase 2 (IDH2) is a major producer of mitochondrial NADPH, required for glutathione (GSH)-associated mitochondrial antioxidant systems including glutathione peroxidase (GPx) and glutathione reductase (GR). Here, we investigated the role of IDH2 in hepatic ischemia-reperfusion (HIR)-associated mitochondrial injury using Idh2-knockout (Idh2(-/-)) mice and wild-type (Idh2(+/+)) littermates. Mice were subjected to either 60min of partial liver ischemia or sham-operation...
September 8, 2017: Redox Biology
C Bodin, E Mourad, D Zigah, S Le Vot, S A Freunberger, F Favier, O Fontaine
Nowadays commercial supercapacitors are based on purely capacitive storage at the porous carbons that are used for the electrodes. However, the limits that capacitive storage imposes on energy density calls to investigate new materials to improve the capacitance of the device. This new type of electrodes (e.g., RuO2, MnO2…) involves pseudo-capacitive faradaic redox processes with the solid material. Ion exchange with solid materials is, however, much slower than the adsorption process in capacitive storage and inevitably leads to significant loss of power...
September 22, 2017: Faraday Discussions
Kirsti Parikka, Ida Nikkilä, Leena Pitkänen, Abdul Ghafar, Tuula Sontag-Strohm, Maija Tenkanen
New wheat arabinoxylan and konjac glucomannan hydrogels and aerogels were prepared by hemiacetal crosslinking induced by laccase/TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) -catalysed oxidation, which selectively converts the primary hydroxyl groups to aldehydes. The degree of oxidation of the product aldehydes was ca. 10% of the total carbohydrates of the polysaccharides, and the determination of storage and viscous moduli of the oxidised samples showed that they had formed true hydrogels. Two freezing methods for the hydrogels, conventional freezing and ice crystal templating, were investigated for aerogel production, the ice crystal templated products especially were mechanically strong in compression test against the ice crystals' growth direction...
November 1, 2017: Carbohydrate Polymers
Nobuhiro Matsumoto, Takuya Shimosaka
The purities of two high-purity organic compounds with a nitroxyl radical moiety were quantified based on their free-radical content using the effective magnetic-moment method. Magnetic moments were measured and X-band electron paramagnetic resonance (EPR) spectra were obtained using a superconducting quantum interference device and X-band EPR spectrometer, respectively, over a wide temperature range of near-room temperature to near-liquid-helium temperature. Concerning measurements of effective g-values using an EPR spectrometer, both the sweep direction and sweep speed were taken into account to obtain accurate g-values...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Qian Zhang, Li Cui, Ping Wang, Chao Deng, Qiang Wang, Xuerong Fan
Silk sericin has excellent features of antioxidant ability and good cytocompatibility; however, high water solubility and poor mechanical properties have restricted its application in biomedical fields. In this study, aimed at improving the mechanical properties of a regenerated silk sericin, the primary hydroxy groups in silk sericin were enzymatically oxidized by using laccase and 2,2',6,6'-tetramethylpiperidine-N-oxyl (TEMPO), and the generated reactive groups then reacted further with the amino groups in the sericin chains...
September 7, 2017: Biotechnology and Applied Biochemistry
Llyza Mendoza, Warren Batchelor, Rico F Tabor, Gil Garnier
HYPOTHESIS: Nanocellulose gels form a new category of sustainable soft materials of industrial interest for a wide range of applications. There is a need to map the rheological properties and understand the mechanism which provides the colloidal stability and gelation of these nanofibre suspensions. EXPERIMENTS: TEMPO (2,2,6,6,-tetramethylpiperidine-1-oxyl)-oxidised cellulose nanofibre gels were investigated at different fibre concentrations, pH and ionic strength...
September 1, 2017: Journal of Colloid and Interface Science
Kazuo Yamagata, Natsumi Takahashi, Nozomi Akita, Toru Nabika
BACKGROUND: Astrocytes support a range of brain functions as well as neuronal survival, but their detailed relationship with stroke-related edema is not well understood. We previously demonstrated that the release of lactate from astrocytes isolated from stroke-prone spontaneously hypertensive rats (SHRSP/Izm) was attenuated under stroke conditions. The supply of lactate to neurons is regulated by astrocytic monocarboxylate transporters (MCTs). The purpose of this study was to examine the contributions of arginine vasopressin (AVP) and/or hypoxia and reoxygenation (H/R) to the regulation of MCTs and neurotrophic factor in astrocytes obtained from SHRSP/Izm and congenic SHRpch1_18 rats...
September 2, 2017: Journal of Neuroinflammation
Aakanksha Wany, Aprajita Kumari, Kapuganti Jagadis Gupta
In response to flooding/water-logging, plants develop various anatomical changes including the formation of lysigenous aerenchyma for the delivery of oxygen to roots. Under hypoxia, plants produce high levels of nitric oxide (NO) but the role of this molecule in plant adaptive response to hypoxia is not known. Here, we investigated whether ethylene-induced aerenchyma requires hypoxia-induced NO. Under hypoxic conditions, wheat roots produced NO apparently via nitrate reductase and scavenging of NO led to a marked reduction in aerenchyma formation...
August 30, 2017: Plant, Cell & Environment
Aza Kobakhidze, Vladimir Elisashvili, Philippe F-X Corvini, Monika Čvančarová
Methylphenidate is widely used as a medication for the treatment of attention deficit hyperactivity disorder (ADHD) in children. Less than 1% of methylphenidate is excreted unchanged in urine, while 80% of an oral dose is excreted as ritalinic acid (which is reportedly poorly degradable). This study aims to investigate the biotransformation of ritalinic acid by free and immobilized enzymes. The influence of various laccase mediators on biotransformation efficiency has been tested. Formation of the main transformation products has been monitored and their potential structures suggested...
August 27, 2017: New Biotechnology
Wenchuan Lai, Dazhou Xu, Xu Wang, Zaoming Wang, Yang Liu, Xiaojiao Zhang, Yulong Li, Xiangyang Liu
Fluorinated graphene (FG) can be regarded as the representative two-dimensional (2D) material to study the characteristics of "2D chemistry", whereas its derivative reaction mechanism is still required to be revealed for the destination of deciduous fluorine atoms after defluorination of FG. Herein, we proposed a particular derivative reaction of FG by employing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as the attacking reagent, and the products were characterized via Electron Paramagnetic Resonance Spectroscopy (EPR), Mass Spectrometry (MS) and X-ray photoelectron spectroscopy (XPS)...
September 13, 2017: Physical Chemistry Chemical Physics: PCCP
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