Toward enhanced catalytic activity of magnetic nanoparticles integrated into 3D reduced graphene oxide for heterogeneous Fenton organic dye degradation

Composite Fenton nanocatalyst was prepared by water-based in situ creation of Fe3O4 nanoparticles integrated within the self-assembly 3D reduced graphene oxide (rGO) aerogel. The hybrid applied for the degradation of Acid Green 25 (AG-25) organic dye in an aqueous solution, in the presence of H2O2. By investigating the conditions that maximize the dye adsorption by the 3D composite, it was found that the pH of the solution should be adjusted between the pKa of the functional groups present on the rGO surface (carboxylic acid) and that of the dye (sulfonic acid) to promote electrostatic interactions dye-3D structure. Performed under these conditions, Fenton degradation of AG-25 in presence of H2O2 was completed in less than 30 min, including all the intermediate products, as demonstrated by MALDI-TOF-MS analysis of the aqueous solution after discoloration. Moreover, this was achieved in a solution with as high a dye concentration of 0.5 mg/mL, with only 10 mg of 3D composite catalyst, at room temperature and without additional energy input. The high performance was attributed to the creation of charge-transfer complex between rGO and Fe3O4 nanoparticles throughout covalent bond C-O-Fe, the formation of which was promoted by the in situ synthesis procedure. For the first time, up to the authors' knowledge, AG-25 degradation mechanism was proposed.The authors gratefully acknowledge the financial support of the Basque Government (GV IT999-16 and GV IT1069-16)

Recyclable Epoxy Resin via Simultaneous Dual Permanent/Reversible Crosslinking Based on Diels-Alder Chemistry

Taking advantage of the reversible Diels-Alder (DA) reaction, a simple strategy to obtain recyclable epoxy resins is presented. For this purpose, blends of furan-functionalized and nonfunctionalized epoxy resin are prepared. After the addition of diamine and bismaleimide, blends are heated at 150 degrees C for 5 min, where the permanent amine/epoxy reaction has taken place and upon cooling to room temperature the reversible DA reaction has happened, giving rise to a dual permanent/nonpermanent network. Both reactions are confirmed by Fourier-transform infrared (FTIR) and C-13-crosspolarization, magic-angle spinning (CP/MAS) nuclear magnetic resonance (NMR). Modulated differential scanning calorimetry (MDSC) shows that the epoxy/amine and bismaleimide/amine curing reaction take place, after the DA reaction, simultaneously with the retroDA reaction and before the bismaleimide homopolymerization. Therefore, under the appropriate curing conditions, the Michael's addition and the bismaleimide homopolymerization do not avoid the formation of a hybrid network, as stated in other reports. The reversibility of the DA reaction in three consecutive cycles is confirmed by DSC. Finally, the dual-cured sample is reprocessed three times without significant loss of mechanical properties.The authors thank the Basque Government (IT1313-19), the University of the Basque Country (GIU19/077), and Mineco (MAT2017-84116-R), for the funding received to develop this work. Technical and human support provided by Macro-Behaviour-Mesostructure and Nanotechnology and NMR SGIker services of UPV/EHU are also gratefully acknowledged. The authors also thank Anne Bravo for the design of the table of contents. Documen

Lisofosfolipidoen eta Alzheimer gaixotasunaren arteko erlazioa: etorkizuneko itu farmakologikoaren bila

Lipidoak funtzio energetikoaz eta egitura-funtzioez gain deskribatu diren beste funtzioei esker garrantzitsuak bilakatzen ari dira. Funtzio neurotransmisorea edota neuromoduladorea aurkeztu duten lipidoen artean, lisofosfolipidoak aurkitu ditzakegu. Lisofosfolipidoak lipido molekula txiki bioaktiboak, karbonodun kate bakarra eta buru polar bat edukitzeagatik bereizten direnak dira. Lisofosfolipidoen artean, azido lisofosfatidikoa eta esfingosina 1-fosfatoaren egitura eta sistemen funtzioak izan dira hobeto deskribatu direnak. Lisofosfolipidoak zelulaz kanpoko bitartekari aritzen dira berentzat espezifikoak diren G proteinei loturiko hartzaileak aktibatuz. Molekula horien seinaleztapenaren bidez zenbait prozesu neurokimiko modulatzen dira, adibidez, neuromodulazioa eta neuroinflamazioa. Gainera, ikasketarekin eta oroimenarekin erlazioa erakutsi dute. Horren haritik, orain arte ondoen deskribatutako lisofosfolipidoen sistemak, azido lisofosfatidikoa eta esfingosina l-fosfatoa, hain zuzen ere, asaldatuta daude Alzheimer gaixotasunean eta gaixotasun honetako zenbait animalia-eredutan. Aldaketa horien zentzua oraindik ez dago finkatuta, baina haien eragina beste neurotransmisio-sistemen edota bestelako funtzio biologikoen modulazioaren bidez gerta daitezke. Beraz, lipido hauek etorkizun handiko itu farmakologikoak izan daitezke Alzheimer gaixotasunean agertzen diren sintoma neuropatologikoak eta neuropsikiatrikoak arintzeko. Hortaz, merkatuan dauden lipidoen seinaleztapena itutzat duten eta beste neuroendekapenezko gaixotasunak tratatzeko erabilgarriak diren farmakoak baliagarriak izan litezke Alzheimer gaixotasuna tratatzeko, aukera emanez horrela Alzheimer gaixotasuna tratatzeko dagoen hutsune farmakologikoa betetzeko.; In addition to energy and structural functions, lipids are becoming important thanks to the other functions described. Some lipids have been shown to exhibit neurotransmitter or neuromodulatory function, including lysophospholipids. Lysophospholipids are small bioactive lipid molecules that are distinguished only by having a single carbon chain and a single polar head. The lysophosphatidic acid and sphingosine l-phosphate structure and system functions are best described among those with neurotransmitter function. Lysophospholipids act as extracellular mediators that activate receptor-specific G proteins that are specific to them. The signaling of these molecules modulate certain neurochemical processes, including neuromodulation and neuroinflammation. They have also presented the relationship with learning and memory. In this respect, the best described lysophospholipid systems, lysophosphatidic acid and sphingosine 1-phosphate, are indeed disturbed in Alzheimer’s disease and in some animal models of this disease. The meaning of these changes is not yet established, but their effect may be related to the modulation of other neurotransmission systems or other biological functions. These lipids are therefore supposed to be the promising pharmacological targets to alleviate the neuropathological and neuropsychiatric symptoms that appear in Alzheimer’s disease. Therefore, marketed drugs that have lipid signaling as a pharmacological target and that are useful to treat other neurodegenerative diseases could be also helpful to treat the Alzheimer’s disease, and with this it might be possible to fill the pharmacological gap in the treatment of Alzheimer’s disease so far

Synthesis of macrocyclic poly(ethylene oxide)s containing a protected thiol group: a strategy for decorating gold surfaces with ring polymers

We introduce an approach to synthesize macrocyclic poly(ethylene oxide)s containing a pendant protected thiol group (pSH-CPEO), which is demonstrated to be able to attach to gold surfaces without prior deprotection. Our strategy is based on a bimolecular approach by which a di-alkyne molecule derived from thiol-protected 3-mercapto-1,2-propanediol and a series of PEO bis(azides) of M-n = 2, 6, and 11 kg mol(-1) are coupled via copper-catalyzed azide-alkyne cycloaddition. The cyclization reaction was verified by size exclusion chromatography and matrix-assisted laser desorption ionization time of flight mass spectrometry. In addition, we used fast scanning calorimetry to evaluate the glass transition temperature (T-g) of the synthesized pSH-CPEOs. Thanks to the extremely rapid cooling power of this technique, PEO crystallization can be circumvented and, therefore, its fully amorphous state can be investigated. The results confirmed higher T-g values for macrocycles compared to their chemically equivalent linear precursors. This result highlights the importance of the chain end in affecting the T-g of polymers. Finally, to demonstrate the ability of pSH-CPEO to covalently attach to gold surfaces, pSH-CPEO samples were allowed to react with gold-coated glass slides and the surface properties were compared with those of the samples obtained by the reaction of linear alpha-thiol, omega-methoxy PEO (with and without protection of the thiol group) and gold-coated glass slides. X-ray photoelectron spectroscopy data confirmed the formation of Au-S linkages as well as the removal of the thiol protector group through the quantitative analysis of the chemical composition at the surface. The contact angle data of pSH-CPEO/gold exhibited increased hydrophilicity compared to bare gold and topological effects at the interface. A reaction mechanism between the 2,4-dinitrobenzene-protected thiol group and the gold surface is also proposed.We thank Dr Farihah M. Haque for helpful discussions on MALDI-TOF MS and Dr. J. I. Miranda for experiments and helpful discussions on NMR. We also gratefully acknowledge support from the Spanish Ministry "Ministerio de Ciencia, Innovacion y Universidades" (PGC2018-094548-B-I00, MICINN/FEDER, UE), Basque Government (IT-1175-19 and PIBA 2018-34), and Diputacion Foral de Guipuzcoa (RED 2018)

A Green Synthesis of Nanocatalysts Based on Reduced Graphene Oxide/Magnetic Nanoparticles for the Degradation of Acid Red 1

The increasing amount of organic dye-polluted wastewater from the textile industry makes the development of techniques for the efficient purification and reuse of wastewater an urgent issue. Accordingly, solid adsorbents based on three-dimensional (3D) reduced graphene oxide (rGO) aerogels combined with magnetic nanoparticles (rGO@Fe3O4) appear to be potential materials, which offer fast and efficient discoloration of dye solutions by dye adsorption, simultaneously acting as Fenton reaction nanocatalysts, and thus may eliminate organic dyes. In this work, 3D rGO@Fe3O4 aerogel nanocatalysts were synthesized via a low-energy, simple, one-step in situ method, in which GO and FeSO4 center dot 7H(2)O were simultaneously reduced. Consequently, monolithic porous nanocatalyst 3D structures were obtained, with a specific surface area of 241 m(2) g(-1) and pore volume 0.39 cm(3) g(-1). The nanocatalysts were applied for the degradation of Acid Red 1 azo-dye in aqueous solution in the presence of hydrogen peroxide, without the need for external energy. The effect of the adsorbent dose, and concentration of dye and peroxide on the dye removal was studied. The degradation of the dye was monitored by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. It was found that an increase in the amount of peroxide allowed complete degradation of the dye together with high molar mass side-products with a conjugated aromatic structure. The good nanocatalyst performance was explained based on the charge-transfer complex established between rGO and the magnetic nanoparticles, allowing the regeneration of ferrous ions during the Fenton process.The authors gratefully acknowledge the financial support by NATO (SfP project G4255), Spanish Government (CTQ2016-80886-R, RTI2018-096294-B-C32 and CTQ2015-73901-JIN), and Basque Government (GV IT999-16 and IT1069-16)

Molecular composition of the human primary visual cortex profiled by multimodal mass spectrometry imaging

The primary visual cortex (area V1) is an extensively studied part of the cerebral cortex with well-characterized connectivity, cellular and molecular architecture and functions (for recent reviews see Amunts and Zilles, Neuron 88:1086–1107, 2015; Casagrande and Xu, Parallel visual pathways: a comparative perspective. The visual neurosciences, MIT Press, Cambridge, pp 494–506, 2004). In humans, V1 is defined by heavily myelinated fibers arriving from the radiatio optica that form the Gennari stripe in cortical layer IV, which is further subdivided into laminae IVa, IVb, IVcα and IVcβ. Due to this unique laminar pattern, V1 represents an excellent region to test whether multimodal mass spectrometric imaging could reveal novel biomolecular markers for a functionally relevant parcellation of the human cerebral cortex. Here we analyzed histological sections of three post-mortem brains with matrix-assisted laser desorption/ionization mass spectrometry imaging and laser ablation inductively coupled plasma mass spectrometry imaging to investigate the distribution of lipids, proteins and metals in human V1. We identified 71 peptides of 13 different proteins by in situ tandem mass spectrometry, of which 5 proteins show a differential laminar distribution pattern revealing the border between V1 and V2. High-accuracy mass measurements identified 123 lipid species, including glycerolipids, glycerophospholipids and sphingolipids, of which at least 20 showed differential distribution within V1 and V2. Specific lipids labeled not only myelinated layer IVb, but also IVa and especially IVc in a layer-specific manner, but also and clearly separated V1 from V2. Elemental imaging further showed a specific accumulation of copper in layer IV. In conclusion, multimodal mass spectrometry imaging identified novel biomolecular and elemental markers with specific laminar and inter-areal differences. We conclude that mass spectrometry imaging provides a promising new approach toward multimodal, molecule-based cortical parcellation

The Influence of Different Fat Sources on Steatohepatitis and Fibrosis Development in the Western Diet Mouse Model of Non-alcoholic Steatohepatitis (NASH)

Non-alcoholic steatohepatitis (NASH) is the leading cause of chronic liver injury and the third most common reason for liver transplantations in Western countries. It is unclear so far how different fat sources in Western diets (WD) influence the development of NASH. Our study investigates the impact of non-trans fat (NTF) and corn oil (Corn) as fat source in a WD mouse model of steatohepatitis on disease development and progression. C57BL/6J wildtype (WT) mice were fed “standard” WD (WD-Std), WD-NTF or WD-Corn for 24 weeks. WT animals treated with WD-NTF exhibit distinct features of the metabolic syndrome compared to WD-Std and WD-Corn. This becomes evident by a worsened insulin resistance and elevated serum ALT, cholesterol and triglyceride (TG) levels compared to WD-Corn. Animals fed WD-Corn on the contrary tend to a weakened disease progression in the described parameters. After 24 weeks feeding with WD-NTF and WD-Std, WD-Corn lead to a comparable steatohepatitis initiation by histomorphological changes and immune cell infiltration compared to WD-Std. Immune cell infiltration results in a significant increase in mRNA expression of the pro-inflammatory cytokines IL-6 and TNF-α, which is more pronounced in WD-NTF compared to WD-Std and WD-Corn. Interestingly the fat source has no impact on the composition of accumulating fat within liver tissue as determined by matrix-assisted laser desorption/ionization mass spectrometry imaging of multiple lipid classes. The described effects of different fat sources on the development of steatohepatitis finally resulted in variations in fibrosis development. Animals treated with WD-NTF displayed massive collagen accumulation, whereas WD-Corn even seems to protect from extracellular matrix deposition. Noteworthy, WD-Corn provokes massive histomorphological modifications in epididymal white adipose tissue (eWAT) and severe accumulation of extracellular matrix which are not apparent in WD-Std and WD-NTF treatment. Different fat sources in WD-Std contribute to strong steatohepatitis development in WT mice after 24 weeks treatment. Surprisingly, corn oil provokes histomorphological changes in eWAT tissue. Accordingly, both WD-NTF and WD-Corn appear suitable as alternative dietary treatment to replace “standard” WD-Std as a diet mouse model of steatohepatitis whereas WD-Corn leads to strong changes in eWAT morphology

Metabolic resistance of the D-peptide RD2 developed for direct elimination of amyloid-β oligomers

Abstract Alzheimer’s disease (AD) is a neurodegenerative disorder leading to dementia. Aggregation of the amyloid-β peptide (Aβ) plays an important role in the disease, with Aβ oligomers representing the most toxic species. Previously, we have developed the Aβ oligomer eliminating therapeutic compound RD2 consisting solely of D-enantiomeric amino acid residues. RD2 has been described to have an oral bioavailability of more than 75% and to improve cognition in transgenic Alzheimer’s disease mouse models after oral administration. In the present study, we further examined the stability of RD2 in simulated gastrointestinal fluids, blood plasma and liver microsomes. In addition, we have examined whether RD2 is a substrate for the human D-amino acid oxidase (hDAAO). Furthermore, metabolite profiles of RD2 incubated in human, rodent and non-rodent liver microsomes were compared across species to search for human-specific metabolites that might possibly constitute a threat when applying the compound in humans. RD2 was remarkably resistant against metabolization in all investigated media and not converted by hDAAO. Moreover, RD2 did not influence the activity of any of the tested enzymes. In conclusion, the high stability and the absence of relevant human-specific metabolites support RD2 to be safe for oral administration in humans