Synergistic effect of electrotrophic perchlorate reducing microorganisms and chemically modified electrodes for enhancing bioelectrochemical perchlorate removal.

Perchlorate has been described as an emerging pollutant that compromises water sources and human health. In this study, a new electrotrophic perchlorate reducing microorganism (EPRM) isolated from the Atacama Desert, Dechloromonas sp. CS-1, was evaluated for perchlorate removal in water in a bioelectrochemical reactor (BER) with a chemically modified electrode. BERs were operated for 17 days under batch mode conditions with an applied potential of -500 mV vs. Ag/AgCl. Surface analysis (i.e., SEM, XPS, FT-IR, RAMAN spectroscopy) on the modified electrode demonstrated heterogeneous transformation of the carbon fibers with the incorporation of nitrogen functional groups and the oxidation of the carbonaceous material. The BERs with the modified electrode and the presence of the EAM reached high cathodic efficiency (90.79 ± 9.157%) and removal rate (0.34 ± 0.007 mol m-3-day) compared with both control conditions. The observed catalytic enhancement of CS-1 was confirmed by a reduction in the charge transfer resistance obtained by electrochemical impedance spectroscopy (EIS). Finally, an electrochemical kinetic study revealed an eight-electron perchlorate bioreduction reaction at -638.33 ± 24.132 mV vs. Ag/AgCl. Therefore, our results show the synergistic effect of EPRM and chemically modified electrodes on perchlorate removal in a BER.

Phenoxy- and Phenylamino-Heterocyclic Quinones: Synthesis and Preliminary Anti-Pancreatic Cancer Activity.

The successful application of fragment-based drug discovery strategy for the efficient synthesis of phenoxy- or phenylamino-2-phenyl-benzofuran, -benzoxazole and -benzothiazole quinones is described. Interestingly, in the final step of the synthesis of the target compounds, unusual results were observed on the regiochemistry of the reaction of bromoquinones with phenol and aniline. A theoretical study was carried out for better understanding the factors that control the regiochemistry of these reactions. The substituted heterocyclic quinones were evaluated in vitro to determine their cytotoxicity by the MTT method in three pancreatic cancer cell lines (MIA-PaCa-2, BxPC-3, and AsPC-1). Phenoxy benzothiazole quinone 26a showed potent cytotoxic activity against BxPC-3 cell lines, while phenylamino benzoxazole quinone 20 was the most potent on MIA-PaCa-2 cells. Finally, electrochemical properties of these quinones were determined to correlate with a potential mechanism of action. All these results, indicate that the phenoxy quinone fragment led to compounds with increased activity against pancreatic cancer cells.

A ternary eutectic solvent for cellulose nanocrystal production: exploring the recyclability and pre-pilot scale-up.

Deep eutectic solvents (DES) formed using choline chloride (ChCl), p-toluenesulfonic acid (pTSA) of stoichiometry ChCl: pTSA (1:1) and (1:2), and its ternary eutectic mixtures with phosphoric acid (PA) 85% as an additive (ChCl: pTSA: PA) were evaluated for cellulose nanocrystal (CNC) isolation. Initially, the hydrolytic efficiency to produce CNC of each DES was compared before and after adding phosphoric acid by Hammett acidity parameters and the Gutmann acceptor number. Moreover, different DES molar ratios and reaction time were studied at 80°C for CNC optimization. The nanomaterial characteristics were analyzed by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The ternary eutectic mixture ChCl: pTSA: PA molar ratio (1:1:1.35) was chosen as a suitable recyclable ternary system at the laboratory scale. A CNC yield of about 80% was obtained from the hydrolysis of commercial cellulose in five cycles of recovery, but it dropped to 35% in pre-pilot scaling. However, no variation in the average size of the resulting CNC was observed (132 ± 50 nm x 23 ± 4 nm), which presented high thermal stability (Tmax 362°C) and high crystallinity of about 80% after 3 h of reaction time.

Cysteine-Mediated Green Synthesis of Copper Sulphide Nanoparticles: Biocompatibility Studies and Characterization as Counter Electrodes.

A one-pot green method for aqueous synthesis of fluorescent copper sulphide nanoparticles (NPs) was developed. The reaction was carried out in borax-citrate buffer at physiological pH, 37 °C, aerobic conditions and using Cu (II) and the biological thiol cysteine. NPs exhibit green fluorescence with a peak at 520 nm when excited at 410 nm and an absorbance peak at 410 nm. A size between 8-12 nm was determined by dynamic light scattering and transmission electron microscopy. An interplanar atomic distance of (3.5 ± 0.1) Å and a hexagonal chalcocite crystalline structure (ßCh) of Cu2S NPs were also determined (HR-TEM). Furthermore, FTIR analyses revealed a Cu-S bond and the presence of organic molecules on NPs. Regarding toxicity, fluorescent Cu2S NPs display high biocompatibility when tested in cell lines and bacterial strains. Electrocatalytic activity of Cu2S NPs as counter electrodes was evaluated, and the best value of charge transfer resistance (Rct) was obtained with FTO/Cu2S (four layers). Consequently, the performance of biomimetic Cu2S NPs as counter electrodes in photovoltaic devices constructed using different sensitizers (ruthenium dye or CdTe NPs) and electrolytes (S2-/Sn2- or I-/I3-) was successfully checked. Altogether, novel characteristics of copper sulfide NPs such as green, simple, and inexpensive production, spectroscopic properties, high biocompatibility, and particularly their electrochemical performance, validate its use in different biotechnological applications.

New Hybrid Copper Nanoparticles/Conjugated Polyelectrolyte Composite with Antibacterial Activity.

In the search for new materials to fight against antibiotic-resistant bacteria, a hybrid composite from metallic copper nanoparticles (CuNPs) and a novel cationic π-conjugated polyelectrolyte (CPE) were designed, synthesized, and characterized. The CuNPs were prepared by chemical reduction in the presence of CPE, which acts as a stabilizing agent. Spectroscopic analysis and electron microscopy showed the distinctive band of the metallic CuNP surface plasmon and their random distribution on the CPE laminar surface, respectively. Theoretical calculations on CuNP/CPE deposits suggest that the interaction between both materials occurs through polyelectrolyte side chains, with a small contribution of its backbone electron density. The CuNP/CPE composite showed antibacterial activity against Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative (Escherichia coli and Salmonella enteritidis) bacteria, mainly attributed to the CuNPs' effect and, to a lesser extent, to the cationic CPE.

Exploring the Effect of the Irradiation Time on Photosensitized Dendrimer-Based Nanoaggregates for Potential Applications in Light-Driven Water Photoreduction.

Fourth generation polyamidoamine dendrimer (PAMAM, G4) modified with fluorescein units (F) at the periphery and Pt nanoparticles stabilized by L-ascorbate were prepared. These dendrimers modified with hydrophobic fluorescein were used to achieve self-assembling structures, giving rise to the formation of nanoaggregates in water. The photoactive fluorescein units were mainly used as photosensitizer units in the process of the catalytic photoreduction of water propitiated by light. Complementarily, Pt-ascorbate nanoparticles acted as the active sites to generate H2. Importantly, the study of the functional, optical, surface potential and morphological properties of the photosensitized dendrimer aggregates at different irradiation times allowed for insights to be gained into the behavior of these systems. Thus, the resultant photosensitized PAMAM-fluorescein (G4-F) nanoaggregates (NG) were conveniently applied to light-driven water photoreduction along with sodium L-ascorbate and methyl viologen as the sacrificial reagent and electron relay agent, respectively. Notably, these aggregates exhibited appropriate stability and catalytic activity over time for hydrogen production. Additionally, in order to propose a potential use of these types of systems, the in situ generated H2 was able to reduce a certain amount of methylene blue (MB). Finally, theoretical electronic analyses provided insights into the possible excited states of the fluorescein molecules that could intervene in the global mechanism of H2 generation.

Detection of hydrophobic microdomains in anionic polyelectrolytes with tris-(4,7-diphenyl-1,10-phenanthroline)3Cr(III).

This paper describes the changes in the luminescent properties of the tris-(4,7-diphenyl-1,10-phenanthroline)(3)Cr(III), [Cr(dip)(3)](3+) complex in an aqueous solution of three polyelectrolytes containing cyclohexyl, phenyl or 1-naphthyl groups in the side chain. When the polyelectrolytes form hydrophobic microdomains the luminescence of [Cr(dip)(3)](3+) is affected. The luminescence increases in the presence of cyclohexyl groups in the side chains, but decreases in the presence of phenyl and naphthyl groups (in that order). This fact can be explained in terms of a reductive quenching mechanism between the complex and the aromatic groups. Indeed, experiments performed with the complex and the alcohols corresponding to the functional groups, i.e., cyclohexanol, phenol, and naphthol, also show the same behavior, confirming the interaction with the functional groups and not other components of the polyelectrolyte. The luminescent properties of the [Cr(dip)(3)](3+) complex allow the detection of hydrophobic microdomains arising from the host-guest interaction. Moreover, the complex is able to distinguish between a nonaromatic hydrophobic microdomain and an aromatic one.

Effects of non-covalent interactions on the electronic and electrochemical properties of Cu(i) biquinoline complexes.

A Cu(i) complex {[CuI(biq)2]ClO4-biq} with biq = 2,2'-biquinoline was prepared, fully characterized and its properties compared with those of the well-known [CuI(biq)2]ClO4 complex. The crystal structures were obtained for both complexes (crystal structure for [CuI(biq)2]ClO4 has not been previously reported). Complex [CuI(biq)2]ClO4 crystallizes as a racemate where each enantiomer has a different τ4 value while compound {[CuI(biq)2]ClO4-biq} crystallizes as a non-chiral supramolecular aggregate with an uncoordinated biq molecule forming a π-π stacking interaction with a coordinated biq. 1H-NMR spectroscopy in non-coordinating solvents reveals that structures in solution are similar to those in the solid phase, confirming the presence of a supramolecular arrangement for compound {[CuI(biq)2]ClO4-biq}. The stability of the non-covalent aggregate in solution of {[CuI(biq)2]ClO4-biq} causes significant differences between the spectroscopic and electrochemical properties of {[CuI(biq)2]ClO4-biq} and [CuI(biq)2]ClO4.

Chitosan/poly-octanoic acid 2-thiophen-3-yl-ethyl ester blends as a scaffold to maintain myoblasts regeneration potential in vitro.

Satellite cells are a small cell population that function as muscle-specific adult stem cells. When muscle damage occurs, these cells are able to activate, proliferate, and ultimately fuse with each other in order to form new myofibers or fuse with existing ones. For tissue engineering applications, obtaining a sufficient number of myoblasts prior transplantation that maintains their regenerative capacity is critical. This can be obtained by in vitro expansion of autologous satellite cells. However, once plated, the self-renewal and regenerative capacity of myoblasts is rapidly lost, obtaining low yields per biopsy. For this purpose, we evaluated in vitro culture of the murine myoblast cell line C2C12 and mouse primary myoblasts with chitosan and chitosan/poly-octanoic acid 2-thiophen-3-yl-ethyl ester blends (poly(OTE)). The films of chitosan/poly(OTE) blends were heterogeneous and slightly rougher than chitosan and poly(OTE) films. Poly(OTE) presence improved myoblast adhesion in both cell types and prevented complete differentiation, but maintaining their differentiation potential in vitro. We identified that the polymer blend chitosan/poly(OTE) could be a suitable substrate to culture satellite cells/myoblasts in vitro preventing differentiation prior transplantation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 118-130, 2017.

Improving myoblast differentiation on electrospun poly(ε-caprolactone) scaffolds.

Polymer scaffolds are used as an alternative to support tissue regeneration when it does not occur on its own. Cell response on polymer scaffolds is determined by factors such as polymer composition, topology, and the presence of other molecules. We evaluated the cellular response of murine skeletal muscle myoblasts on aligned or unaligned fibers obtained by electrospinning poly(ε-caprolactone) (PCL), and blends with poly(lactic-co-glycolic acid) (PLGA) or decorin, a proteoglycan known to regulate myogenesis. The results showed that aligned PCL fibers with higher content of PLGA promote cell growth and improve the quality of differentiation with PLGA scaffolds having the highest confluence at over 68% of coverage per field of view for myoblasts and more than 7% of coverage for myotubes. At the same time, the addition of decorin greatly improves the quantity and quality of differentiated cells in terms of cell fusion, myotube length and thickness, being 71, 10, and 51% greater than without the protein, respectively. Interestingly, our results suggest that at certain concentrations, the effect of decorin on myoblast differentiation exceeds the topological effect of fiber alignment. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2241-2251, 2017.

Electrocatalytic Transformation of Carbon Dioxide into Low Carbon Compounds on Conducting Polymers Derived from Multimetallic Porphyrins.

The electrochemical reduction of carbon dioxide is studied herein by using conducting polymers based on metallotetraruthenated porphyrins (MTRPs). The polymers on glassy carbon electrodes were obtained by electropolymerization processes of the monomeric MTRP. The linear sweep voltammetry technique resulted in polymeric films that showed electrocatalytic activity toward carbon dioxide reduction with an onset potential of -0.70 V. The reduction products obtained were hydrogen, formic acid, formaldehyde, and methanol, with a tendency for a high production of methanol with a maximum value of turnover frequency equal to 15.07 when using a zinc(II) polymeric surface. Studies of the morphology (AFM) and electrochemical impedance spectroscopy results provide an adequate background to explain that the electrochemical reduction is governed by the roughness of the polymer, for which the possible mechanism involves a series of one-electron reduction reactions.

Photoelectrochemical Reduction of Carbon Dioxide on Quantum-Dot-Modified Electrodes by Electric Field Directed Layer-by-Layer Assembly Methodology.

The photoelectrocatalytic reduction of CO2 on ITO-modified electrodes, with electrostatic assemblies (polycations/quantum dots) (polycations=poly diallyldimethylammonium, PDDA, and poly(2-trimethylammonium)ethyl methacrylate, PMAEMA)), is described in the present work. Nanoparticles of CdTe (5.6 nm) were incorporated through an electric field directed layer-by-layer assembly method on ITO electrodes. Modified surfaces were active toward the reduction of CO2 at -400 mV vs Ag/AgCl; the activity of ITO-(PMAEMA/QDs)6 electrodes was enhanced by 300 mV under irradiation conditions. The photoelectrocatalytic effect was associated with the structure of the polycation and its influence in the assembly. Reaction products at -450 mV were H2, CO, CH3OH, and HCOH.

Toward a pK(a) scale of N-base amines in ionic liquids.

An electrochemical technique was used to investigate pKa values of some substituted secondary alicyclic (SA) amines, pyridines (py), anilines (AN), and triethylamine (Et3N) in different ionic liquids. The method involves cyclic voltammetry at a platinized Pt electrode. The experimental data were correlated with pKa values reported previously in aqueous solution, and Hammett parameters were correlated with pKa values in ionic liquids to determine ρ values in these media.

Anthocyanin composition in aged Chilean Cabernet Sauvignon red wines.

Anthocyanins in aged Cabernet Sauvignon red wines were studied by HPLC-MS. The major anthocyanin in 6, 7, and 8year old red wine extracts was the dimer vitisin A produced by condensation of malvidin-3-O-glucoside mediated by pyruvic acid. In aged wine, the content of malvidin-3-O-glucoside decreased with age with a concomitant increase of vitisin A. The latter is accompanied by several condensation products with molecular weight up to 1500m/z. Differential pulse voltammetry indicated that aged wines have lower antioxidant capacity than young wine (400mV), but higher than malvidin-3-O-glucoside (483mV). Tafel's plots showed that the electrochemical process occurring in aged wines is different from young wines. Six, seven and eight year old wines show similar behaviour with plots of 234, 177 and 188mV/dec, respectively. These values are higher than the expected 120mV/dec corresponding to a first electronic transfer but smaller compared to the 523mV/dec corresponding to young wine.

Antifungal activity of resveratrol against Botrytis cinerea is improved using 2-furyl derivatives.

The antifungal effect of three furyl compounds closely related to resveratrol, (E)-3,4,5-trimethoxy-ß-(2-furyl)-styrene (1), (E)-4-methoxy-ß-(2-furyl)-styrene (2) and (E)-3,5-dimethoxy-ß-(2-furyl)-styrene (3) against Botrytis cinerea was analyzed. The inhibitory effect, at 100 µg ml(-1) of compounds 1, 2, 3 and resveratrol on conidia germination, was determined to be about 70%, while at the same concentration pterostilbene (a dimethoxyl derivative of resveratrol) produced complete inhibition. The title compounds were more fungitoxic towards in vitro mycelial growth than resveratrol and pterostilbene. Compound 3 was the most active and a potential explanation of this feature is given using density functional theory (DFT) calculations on the demethoxylation/demethylation process. Compound 3 was further evaluated for its effects on laccase production, oxygen consumption and membrane integrity of B. cinerea. An increase of the laccase activity was observed in the presence of compound 3 and, using Sytox Green nucleic acid stain, it was demonstrated that this compound altered B. cinerea membrane. Finally, compound 3 partially affected conidia respiration.