Characterization of interactions of eggPC lipid structures with different biomolecules

In this paper we study the interactions of two biomolecules (ascorbic acid and Annonacin) with a bilayer lipid membrane. Egg yolk phosphatidylcholine (eggPC) liposomes (in crystalline liquid state) were prepared in solutions of ascorbic acid (AA) at different concentration levels. On the other hand, liposomes were doped with Annonacin (Ann), a mono-tetrahydrofuran acetogenin (ACG), which is an effective citotoxic substance. While AA pharmacologic effect and action mechanisms are widely known, those of Ann’s are only very recently being studied. Both Fourier Transformed Infrared (FTIR) and Raman spectroscopic techniques were used to study the participation of the main functional groups of the lipid bilayer involved in the membrane-solution interaction. The obtained spectra were comparatively analyzed, studying the spectral bands corresponding to both the hydrophobic and the hydrophilic regions in the lipid bilayer. Electrochemical experiments namely; impedance spectroscopy (EIS) and cyclic voltamperometry (CV) were used as the main characterization techniques to analyse stability and structural changes of a model system of supported EggPC bilayer in connection with its interactions with AA and Ann. At high molar ratios of AA, there is dehydration in both populations of the carbonyl group of the polar head of the lipid. On the other hand, Ann promotes the formation of hydrogen bonds with the carbonyl groups. No interaction between AA and phosphate groups is observed at low and intermediate molar ratios. Ann is expected to be able to induce the dehydration of the phosphate groups without the subsequent formation of H bonds with them. According to the electrochemical analysis, the interaction of AA with the supported lipid membrane does not alter its dielectric properties. This fact can be related to the conservation of structured water of the phosphate groups in the polar heads of the lipid. On the other hand, the incorporation of Ann into the lipid membrane generates an increase in the number of defects while changes the dielectric constant. This, in turn, can be associated with the induced dehydration of the phosphate groups.Facultad de Ciencias ExactasFacultad de Ingeniería (FI)Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA

Characterization of interactions of eggPC lipid structures with different biomolecules

In this paper we study the interactions of two biomolecules (ascorbic acid and Annonacin) with a bilayer lipid membrane. Egg yolk phosphatidylcholine (eggPC) liposomes (in crystalline liquid state) were prepared in solutions of ascorbic acid (AA) at different concentration levels. On the other hand, liposomes were doped with Annonacin (Ann), a mono-tetrahydrofuran acetogenin (ACG), which is an effective citotoxic substance. While AA pharmacologic effect and action mechanisms are widely known, those of Ann’s are only very recently being studied. Both Fourier Transformed Infrared (FTIR) and Raman spectroscopic techniques were used to study the participation of the main functional groups of the lipid bilayer involved in the membrane-solution interaction. The obtained spectra were comparatively analyzed, studying the spectral bands corresponding to both the hydrophobic and the hydrophilic regions in the lipid bilayer. Electrochemical experiments namely; impedance spectroscopy (EIS) and cyclic voltamperometry (CV) were used as the main characterization techniques to analyse stability and structural changes of a model system of supported EggPC bilayer in connection with its interactions with AA and Ann. At high molar ratios of AA, there is dehydration in both populations of the carbonyl group of the polar head of the lipid. On the other hand, Ann promotes the formation of hydrogen bonds with the carbonyl groups. No interaction between AA and phosphate groups is observed at low and intermediate molar ratios. Ann is expected to be able to induce the dehydration of the phosphate groups without the subsequent formation of H bonds with them. According to the electrochemical analysis, the interaction of AA with the supported lipid membrane does not alter its dielectric properties. This fact can be related to the conservation of structured water of the phosphate groups in the polar heads of the lipid. On the other hand, the incorporation of Ann into the lipid membrane generates an increase in the number of defects while changes the dielectric constant. This, in turn, can be associated with the induced dehydration of the phosphate groups.Facultad de Ciencias ExactasFacultad de Ingeniería (FI)Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA

The STRIP instrument of the Large Scale Polarization Explorer: microwave eyes to map the Galactic polarized foregrounds

In this paper we discuss the latest developments of the STRIP instrument of the "Large Scale Polarization Explorer" (LSPE) experiment. LSPE is a novel project that combines ground-based (STRIP) and balloon-borne (SWIPE) polarization measurements of the microwave sky on large angular scales to attempt a detection of the "B-modes" of the Cosmic Microwave Background polarization. STRIP will observe approximately 25% of the Northern sky from the "Observatorio del Teide" in Tenerife, using an array of forty-nine coherent polarimeters at 43 GHz, coupled to a 1.5 m fully rotating crossed-Dragone telescope. A second frequency channel with six-elements at 95 GHz will be exploited as an atmospheric monitor. At present, most of the hardware of the STRIP instrument has been developed and tested at sub-system level. System-level characterization, starting in July 2018, will lead STRIP to be shipped and installed at the observation site within the end of the year. The on-site verification and calibration of the whole instrument will prepare STRIP for a 2-years campaign for the observation of the CMB polarization.Comment: 17 pages, 15 figures, proceedings of the SPIE Astronomical Telescopes + Instrumentation conference "Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX", on June 15th, 2018, Austin (TX

Titanium dioxide nanoparticles promote arrhythmias via a direct interaction with rat cardiac tissue

BackgroundIn light of recent developments in nanotechnologies, interest is growing to better comprehend the interaction of nanoparticles with body tissues, in particular within the cardiovascular system. Attention has recently focused on the link between environmental pollution and cardiovascular diseases. Nanoparticles <50 nm in size are known to pass the alveolar¿pulmonary barrier, enter into bloodstream and induce inflammation, but the direct pathogenic mechanisms still need to be evaluated. We thus focused our attention on titanium dioxide (TiO2) nanoparticles, the most diffuse nanomaterial in polluted environments and one generally considered inert for the human body.MethodsWe conducted functional studies on isolated adult rat cardiomyocytes exposed acutely in vitro to TiO2 and on healthy rats administered a single dose of 2 mg/Kg TiO2 NPs via the trachea. Transmission electron microscopy was used to verify the actual presence of TiO2 nanoparticles within cardiac tissue, toxicological assays were used to assess lipid peroxidation and DNA tissue damage, and an in silico method was used to model the effect on action potential.ResultsVentricular myocytes exposed in vitro to TiO2 had significantly reduced action potential duration, impairment of sarcomere shortening and decreased stability of resting membrane potential. In vivo, a single intra-tracheal administration of saline solution containing TiO2 nanoparticles increased cardiac conduction velocity and tissue excitability, resulting in an enhanced propensity for inducible arrhythmias. Computational modeling of ventricular action potential indicated that a membrane leakage could account for the nanoparticle-induced effects measured on real cardiomyocytes.ConclusionsAcute exposure to TiO2 nanoparticles acutely alters cardiac excitability and increases the likelihood of arrhythmic events

Corrosion Inhibition of Aluminum in Acidic Solution by <i>Ilex paraguariensis</i> (Yerba Mate) Extract as a Green Inhibitor

In the present work, the inhibitory effect of Ilex paraguariensis (Yerba Mate) extract on the corrosion of aluminum in 0.1 M HCl solution, in the temperature range of 298–323 K, was studied by using weight loss tests, potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). The extract of Ilex paraguariensis exhibits improved inhibitory action as its concentration increases while its performance is maintained despite an increase in temperature. EIS theoretical data according to a suitable proposed equivalent circuit were successfully fitted to the experimental data. The adsorption of organic compounds followed a modified Langmuir isotherm behaviour. Derived thermodynamic parameters indicate the occurrence of both chemical and physical adsorption

Síntesis y caracterización de un sistema electroestimulado

Los hidrogeles electroconductores son compuestos 3D formados por matrices poliméricas de distinta naturaleza como los&nbsp; hidrogeles y los polímeros conductores, los cuales le confieren al compósito propiedades ópticas, eléctricas y redox únicas. Estos materiales híbridos&nbsp; pueden ser utilizados como biomateriales&nbsp;&nbsp; en biosensoresimplantables o sistemas de suministro controlado de medicamentos.&nbsp; En el presente trabajo se estudió la síntesis y caracterización de un sistema electroestimulado a partir de polipirrol (PPy) y el microgel responsivo a base de poli(2-dietilamino etilimetacrilato) (pDEAEMA). Además se investigó la liberación electroestimulada usando Rodamina 6G (Rh6G) como droga modelo

Síntesis y caracterización de un sistema electroestimulado

Los hidrogeles electroconductores son compuestos 3D formados por matrices poliméricas de distinta naturaleza como los&nbsp; hidrogeles y los polímeros conductores, los cuales le confieren al compósito propiedades ópticas, eléctricas y redox únicas. Estos materiales híbridos&nbsp; pueden ser utilizados como biomateriales&nbsp;&nbsp; en biosensoresimplantables o sistemas de suministro controlado de medicamentos.&nbsp; En el presente trabajo se estudió la síntesis y caracterización de un sistema electroestimulado a partir de polipirrol (PPy) y el microgel responsivo a base de poli(2-dietilamino etilimetacrilato) (pDEAEMA). Además se investigó la liberación electroestimulada usando Rodamina 6G (Rh6G) como droga modelo

Use of Urea-imprinted cobalt ferrite nanoparticles in deacidification of deteriorated vegetable oil: Synthesis, characterization and preclinical toxicity screening

Finding an affordable solution to the challenge posed by quality deterioration and loss of vitality of vegetable oil is of concern to the food industry. This study evaluated the synthesis of cobalt ferrite (CoFe2O4) and urea modified cobalt ferrite (CoFe2O4@Urea) via the coprecipitation method and their application to the sorption of free fatty acids (FFAs) in deteriorated vegetable oil (DVO). CoFe2O4 and CoFe2O4@Urea were characterized by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The crystallite size was found to be 29 nm for CoFe2O4 and 31 nm for CoFe2O4@Urea. CoFe2O4 and CoFe2O4@Urea exhibited high performance for the removal of FFA from DVO restoring its loss quality. The negative values of ΔGo for both CoFe2O4 and CoFe2O4@Urea are indications that the sorption process is spontaneous with an increased percentage removal of FFA from 77.80 % in CoFe2O4 to 97.50 % in CoFe2O4@Urea in a process that may be described by Freundlich, Langmuir, and Temkin isotherm models. CoFe2O4@Urea (195.00 L kg−1) exhibited a better sorption capacity than CoFe2O4 (155.60 L kg−1); in furtherance of this exhibited performance, CoFe2O4@Urea (20 and 40 mg kg−1) was fed to rats for 7 days and assessed for sero-clinical and morphological alterations in the liver and kidney. Incidentally, treatment of rats with CoFe2O4@Urea did not affect clinical parameters including albumin, calcium, triglycerides and creatinine. Contrariwise, the biochemical markers of hepatorenal function, aspartate aminotransferase and bilirubin were significantly depleted following treatment with 20 mg kg−1 CoFe2O4@Urea while micromorphological studies indicated the presence of congestion and infiltration of the hepatic portal tract. These studies established the outstanding performance of CoFe2O4@Urea for restoring the quality of DVO which paves the way for the future prospects of CoFe2O4@Urea in the treatment of DVO in the food industry.Fil: Adewuyi, Adewale. Redeemer‘s University; Nigeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Otuechere, Chiagoziem A.. Redeemer‘s University; NigeriaFil: Gervasi, Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Olukanni, Adedayo T.. Redeemer‘s University; NigeriaFil: Yawson, Emmanuel. Redeemer‘s University; NigeriaFil: Rubert, Aldo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Mirifico, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Electronic Structure of Tin Passive Films and Its Influence on the Corrosion of the Base Metal

Passive dissolution and electronic properties of anodic passive layers developed on tin in citrate buffer pH 3 have been analyzed. This study is relevant to corrosion of tinplate in canned fruit juices. The existence of a direct relationship has been established between the structure and electronic properties of the passive film and the electrochemical reduction of oxygen on its surface. The passive film is made of at least two oxides with different compositions and electronic structures. The inner barrier layer exhibits poorer stability and consequently affords tin lower protection against corrosion. However, due to a more cathodic flat-band potential, this layer is related to large overpotentials for the cathodic reaction during localized corrosion processes, namely, oxygen reduction in aerated media. Dissolution of tin takes place with formation of a dissolved Sn­(IV)-citrate complex

Molecular Transport in Thin Thermoresponsive Poly(<i>N</i>-isopropylacrylamide) Brushes with Varying Grafting Density

The effect of the grafting density on the molecular transport through thermoresponsive brushes of poly­(<i>N</i>-isopropylacrylamide) (PNIPAM) grafted onto flat gold substrates was investigated using voltammetry and impedance spectroscopy. PNIPAM brush layers were synthesized at four different grafting densities using surface-initiated atom transfer radical polymerization (SI-ATRP) from mixed self-assembled monolayers of ω-mercaptoundecyl bromoisobutyrate and undecanethiol chemisorbed on gold surfaces. Tethered PNIPAM layers with grafting densities resulting from initiator concentrations lower than 25% in the thiol monolayer show the same transport properties as the initial self-assembled monolayer before brush synthesis. For higher grafting densities, the diffusion coefficients, <i>D</i>, of the K₃[Fe­(CN)₆]/K₄[Fe­(CN)₆] redox probe is 7 orders of magnitude smaller than those typically measured in aqueous solutions and independent of whether the brush is collapsed or swollen. The collapse of the PNIPAM brush drives a hydrophilic/hydrophobic transition in addition to structural/conformational transformations of the grafted layers, resulting in still smaller values of <i>D</i>. However, these changes do not lead to a blocking effect on the active area of the gold surface, which is only determined by pinholes or discontinuities in the thiol initiator monolayer. These results are only observed for thin PNIPAM brush layers