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This work presents the synthesis of platinum and silver nanoparticles obtained on a support composed of the S-layer protein (SLP) isolated from Lactobacillus kefiri and polyurethane particles (PU). The support was obtained by adsorption of the protein on the polymer particles in aqueous dispersion. After combining the support with the platinum or silver salts and subsequently reducing with hydrogen, noble metal-based heterogeneous bionanocatalysts were obtained. Platinum or silver nanoparticles with diameters dn = 4.9 nm (ds = 4.9 nm; dv/dn = 1.05) or dn = 8.0 nm (ds = 10.6 nm; dv/dn = 1.63), respectively, were observed by TEM on the surface of the protein/polymer supports. Both nanocatalysts showed excellent catalytic activity in the reduction of p-nitrophenol with NaBH4 at room temperature, with conversions of 100% and 97% for platinum and silver bionanocatalysts, respectively. Noteworthy, both bionanocatalysts maintain their activity until 4 reuse cycles, being the platinum-based system the one showing the best performance. These results demonstrated that the developed bionanocatalysts are promising and emerging alternatives in the field of supported noble metal nanoparticle-based heterogeneous catalysts.

This work presents the preparation of polyurethane composite foams based on castor oil or modified canola oil as a polyol, and cellulose nanocrystals (CN) as nanofiller (0.10, 0.25, and 0.50 wt% of CN content). The bio-based composites were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and mechanical properties. The SEM images showed that composite foams had smaller cell sizes and more irregular than those observed for unloaded samples. FTIR revealed that the urethane/urea bond formation was influenced by the incorporation of CN, and was dependent on the polyol used in the formulation. The incorporation of CN did not affect the thermal stability, but the density and mechanical properties changed differently depending on the selected polyol. These results suggested that the acylglycerol structure affects the role of CN in the formulation. Also, the proliferation of MC3T3-E1 preosteoblastic cells showed that the cell viability of polyurethane bionanocomposite foams increased significantly in comparison to the unloaded material. Fil: Gangoiti, Maria Virginia. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Ciencias Biológicas. Laboratorio de Investigación en Osteospatías y Metabolismo Mineral; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Peruzzo, Pablo Jose. 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; Argentina. Universidad Nacional Arturo Jauretche; Argentina

The increased interest of consumers in probiotic foods requires a deeper knowledge on the possible interactions with drugs, because their pharmacological properties could be modified. In this context, these studies are relevant for drugs such as acenocoumarol, whose dosage must be controlled due to, among other factors, food-drug interactions. Acenocoumarol is an oral anticoagulant with a narrow therapeutic range. The aim of the present research is to evaluate, in vitro, the effect of bifidobacteria on acenocoumarol. The drug was incubated with Bifidobacterium bifidum CIDCA 5310 or Bifidobacterium adolescentis CIDCA 5317 in MRS broth at 37°C for 24 h in anaerobic conditions. The effect of incubation with sterilized spent culture supernatants (SSCS) was also evaluated. Analysis by RP-HPLC showed that both bifidobacterial strains reduced the area of the acenocoumarol peak and two new peaks were evidenced. In addition, a decrease in the intensity of the bands at 1650, 1390 and 1110/cm was observed in the FTIR spectroscopic determinations. Moreover, a new band appeared at 1720/cm. No effect on the drug was observed when incubation was performed with SSCS. The present study showed a significant change in the concentration of the anticoagulant after incubation with bifidobacteria and results are compatible with biomodification of the drug due to enzymatic activity of bifidobacteria.

Polymersomes are polymer-based vesicles that form upon hydration of amphiphilic block copolymers and display high stability and durability, due to their mechanical and physical properties. They have hydrophilic reservoirs as well as thick hydrophobic membranes; allowing to encapsulate both water-soluble bioactive agent and hydrophobic drugs. In this study, poly ethylene glycol (PEG3350 and PEG6000) were used as hydrophilic part and poly(vinyl benzoate) (PVBz) as hydrophobic block to synthesize amphiphilic triblock copolymers (PVBz-b-PEG-b-PVBz). Different proportions of hydrophilic/hydrophobic part were assayed in order to obtain polymersomes by solvent injection method. For the synthesis of the copolymers, the initial block of PEG was derived to obtain a macroinitiator through a xanthate functional group (PEGX3 or PEGX6) and the polymerization of vinyl benzoate was carried out through reversible addition-fragmentation chain transfer polymerization (RAFT). The structure of PEGX and copolymers was confirmed by Infrared, ¹H-NMR and UV-Vis spectrometry, while the average molecular weight (Mw) and polydispersity index (PI) were determined by size exclusion chromatography (SEC). The structures adopted by the copolymers in aqueous solution by self-assembly were investigated using transmission electron microscopy (TEM), dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). Both techniques confirm that polymersomes were obtained for a fraction of hydrophilic block (f) ≈ 35 ± 10%, with a diameter of 38.3 ± 0.3 nm or 22.5 ± 0.7 nm, as determined by TEM and according to the M; w; of the precursor block copolymer. In addition, we analyzed the possible cytotoxicity in view of its potential application as biomedical nanocarrier. The results suggest that polymersomes seem not induce cytotoxicity during the periods of time tested., Laboratorio de Investigación en Osteopatías y Metabolismo Mineral, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas

An active film prepared from waterborne polyurethane incorporated with different concentrations of butylated hydroxytoluene (BHT) and α-tocopherol was developed, and the films? antioxidant characteristics were studied using soybean oil as food model. The release behavior of additives from such films was studied using isooctane as a simulant fatty food. Antioxidant activity of the films into soybean oil at three experimental conditions was monitored by FTIR spectroscopy. Induction time and the kinetics of the oxidation process were followed using different bands of the FT-IR spectra. Films incorporated with 2 wt.% of BHT or α-tocopherol showed enough antioxidant activity to preclude oil oxidation during 60 days at 60 °C in the dark. The results showed that this type of active films could be used for food preservation as part of a packaging containing oils or oily related products. Fil: Anbinder, Pablo Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; Argentina Fil: Peruzzo, Pablo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; Argentina Fil: Martino, Miriam Nora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones en Criotecnología de Alimentos (i); Argentina. Universidad Nacional de La Plata; Argentina Fil: Amalvy, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigación y Desarrollo en Tecnología de Pinturas (i); Argentina

This work presents the study of the isolation of chitin from residues of the Patagonian shrimp (Pleoticus muelleri), and its subsequent conversion to chitosan under different reaction conditions. The obtained products were characterized by evaluating their molecular weight (Mw) and degree of deacetylation (DD). In addition, chitosan- glycerol films were prepared (5, 10 and 20% w/w of plasticizer content), using a neutralization process during the unmolding step. The films were characterized by infrared (FTIR) and UV-Visible spectroscopy and scanning electron microscopy (SEM). In addition, its behavior against water (contact angle and water sorption) and mechanical properties were also studied. It was observed that 72 hours of reaction time at 120 °C were necessary to obtain a chitosan sample with the desirable solubility properties from the chitin extracted from Pleoticus muelleri shells. The chitosan-glycerol films turned out to be systems of high transparency and their properties depended on the plasticizer content, obtaining homogeneous systems for concentrations up to 10% w/w. In addition, the films were found to be more hydrophilic than the reference material, with smaller contact angle and greater water absorption values, obtaining more flexible films in view of their mechanical properties., Facultad de Ingeniería, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas

30 p.-4 fig.-3 tab., Lactobacillus plantarum CIDCA 8327 is an exopolysaccharide (EPS)-producer strain isolated from kefir with promising properties for the development of functional foods. The aim of the present study was to characterize the structure of the EPS synthesized by this strain grown in skim milk or semidefined medium (SDM). Additionally, genes involved in EPS synthesis were detected by PCR. L. plantarum produces an EPS with a molecular weight of 104 Da in both media. When grown in SDM produce an heteropolysaccharide composed mainly of glucose, glucosamine and rhamnose meanwhile the EPS produced in milk was composed exclusively of glucose indicating the influence of the sugar source. FTIR spectra of this EPS showed signals attributable to an α-glucan. Both by 1H NMR and methylation analysis it was possible to determine that this polysaccharide is a branched α-(1 → 4)-d-glucan composed of 80% linear α-(1 → 4)-d-glucopyranosyl units and 19% (1 → 4)-d-glucopyranosyl units substituted at O-3 by single α-d-glucopyranosil residues., This study was supported by grants from the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT), CONICET and UNLP, the Spanish Ministry of Science and Innovation (AGL2012-40084-C03), the Basque Government (no. IT866-13).

This work presents the synthesis of new copolymers based on dioctyl fumarate (DOF) and vinyl benzoate (VB) and their application as flow improvers in a waxy crude oil. The copolymers were obtained by solution radical polymerization starting from a broad range of monomer compositions (fDOF) and characterized by Fourier-transform infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance (1H-NMR) Spectroscopy and Size exclusion chromatography. Results indicated that polymerization yield and molecular weight increases with decrease in fDOF. Based on the composition of the copolymers the reactivity coefficients of the monomers were obtained, whose product r1. r2 = 0.042 indicates a copolymerization behavior with a high tendency to alternating copolymerization. Selected copolymers varying composition or molecular weight, were used as additive at different concentration to evaluate the effect of these variables on their performance as flow improvers in a waxy crude oil composed of paraffin with high average carbon number and a narrow carbon number distribution. The analysis was done through differential scanning calorimetry and rheological measurements. The addition of the lowest molecular weight copolymer resulted in the best efficacy as flow improver, while the highest molecular weight rich in VB copolymer produced an unwanted effect that worsen the flow properties of waxy crude oil at low temperatures. Fil: Coussirat, Vladimir. 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; Argentina Fil: Amarilla, Fernando Enrique. 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; Argentina Fil: Peruzzo, Pablo Jose. 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; Argentina Fil: Cortizo, Maria Susana. 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; Argentina

Chitosan/cellulose nanocrystals (CH-CN) films were obtained by casting of dispersions, and treated withNaOH for neutralization proposes. The composition of films was varied from 1 to 10 wt.% of CN. Changesin the morphology of the systems were correlated with the different properties studied. FTIR revealedthe presence of a weak interaction between the polymer matrix and nanofiller, confirmed by a slightlyincrease in thermal stability. SEM images suggested that incorporating CN amounts higher than 3 wt.%generates phase-segregated systems, and SAXS showed that CH avoid the typical organization of CN atconcentrations below 5 wt.%. Improved performance against water was obtained in composite materialscomparing to the pure polymer matrix, as well as CH and CH-CN films did not show antibacterial activitydemonstrating that remnant acetic acid, when no neutralization step is done, plays an important role inthis property., Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Centro de Investigación y Desarrollo en Ciencias Aplicadas

In this work the synthesis of waterborne polyurethane/nanosilica nanocomposites by using two different strategies is presented, starting from a vinyl terminated polyurethane prepolymer (PUP) based on isophorone diisocyanate and polypropylene glycol, and varying the nanosilica content. In one case, the PUP was dispersed in an aqueous solution containing glycerol-functionalized colloidal nanosilica particles and the dispersion was further polymerized; in the other case, the PUP was dispersed in an aqueous media, then colloidal nanosilica was added to the dispersion and then polymerized. A physical mixture was also prepared for comparative purpose. Films were prepared by casting of the aqueous dispersion. The morphology of the dispersions and films depended on the incorporation route of nanoparticles as was observed by SAXS, SEM and TEM. While the blends had significantly less hydrogen bonding between the hard segments of the PU and nanosilica particles, samples prepared by the two different methods proposed in this work showed an strong interaction between both materials in agreement with FTIR and DSC results. Synthesis pathway plays an important role in order to obtain high performance waterborne polyurethane/nanosilica composites, since final properties of the films also depended on the nanoparticle incorporation strategy. Fil: Peruzzo, Pablo Jose. 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; Argentina Fil: Anbinder, Pablo Sebastián. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física de Materiales; Argentina Fil: Pardini, Francisco Martín. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentina Fil: Pardini, Oscar Ricardo. 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; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentina Fil: Plivelic, Tomás S.. Lund University; Suecia Fil: Amalvy, Javier. 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; Argentina

Silicon nanoparticles with strong blue photoluminescence were synthesized by electrochemical etching of silicon wafers and ultrasonically removed under N2 atmosphere in organic solvents to produce colloids. Thermal treatment leads to the formation of colloidal Si particles of 3 ± 1 nm diameter, which upon excitation with 340−380 nm light exhibited room temperature luminescence in the range from 400 to 500 nm. The emission and the one- and two-photon excitation spectra of the particles are not sensitive to surface functionalization with methyl 2-methylprop-2-enoate. However, the derivatized particles show higher emission quantum yields in air-saturated suspensions (44%) than the underivatized particles (27%), as well as higher stability of its dispersions. FTIR and XPS spectra indicate a significant surface oxidation of the particles. The Si:O:C ratio at the surface of the derivatized particles estimated from XPS is Si3O6(C5O2Hy)1, with y = 7−8. Vibronic spacing is observed in both the emission and excitation spectra. The information obtained from one-photon excitation experiments (emission and excitation spectra, photoluminescence quantum yields, luminescence decay lifetimes, and anisotropy correlation lifetimes), as well as from two-photon excitation fluorescence correlation spectroscopy (brightness and diffusion coefficients) and TEM, indicate that the blue-emitting particles are monodisperse and ball-shaped. Particle size clearly determines the emission and excitation spectral region, as expected from quantum confinement, but the presence and extent of Si−O species on the silicon networks seem crucial for determining the spectrum features and intensity of emission. The nanoparticles could hold great potential as quantum dots for applications as luminescence sensors in biology and environmental science., Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas

Levels of glyphosate were determined in water, soil and sediment samples from a transgenic soybean cultivation area located near to tributaries streams of the Pergamino-Arrecifes system in the north of the Province of Buenos Aires, Argentina. Field work took into account both the pesticide application and the rains occurring after applications. The pesticide was analysed by HPLC-UV detection, previous derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl). In addition, SoilFug multimedia model was used to analyse the environmental distribution of the pesticides. In the field, levels of glyphosate in waters ranged from 0.10 to 0.70 mg/L, while in sediments and soils values were between 0.5 and 5.0 mg/Kg. Temporal variation of glyphosate levels depended directly on the time of application and the rain events. The results obtained from the application of the model are in accordance with the values found in the field.

The Wiener index W is the oldest molecular-graph-based structure-descriptor. It is defined as the sum of the distances of all pairs of vertices of the molecular graph G, where the distance is the number of edges in the shortest path connecting the respective vertices, and where G is the hydrogen-depleted molecular graph. This seemingly very simple topological index could be "upgraded" (a) by using as the distance the sum of the bond lengths along the shortest path, or (b) by using the Euclidean distance between the respective pairs of atoms. Each of these "upgraded" Wiener indices could be computed either (α) for the hydrogen-depleted or (β) for the hydrogen-filled molecular graph. We provide examples showing that none of the modifications (aα), (aβ), (bα), (bβ) yields better results than the ordinary Wiener index, and that there is a very good linear correlation between W and its "upgraded" variants., Centro de Química Inorgánica (CEQUINOR)