Artículos de publicaciones periódicas

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NMR Study of the dynamic equilibria among isomeric species in quinoxalin-2-one derivatives
(2024) Barrionuevo, Emiliano; Jasinski, Gabriel; Fabian, Lucas; Martini, M. Florencia; Moglioni, Albertina
The understanding of the prototropic lactam/lactim/enol equilibrium and the E/Z isomerism around the N-C(O) bond in amides is important for the determination of different physicochemical properties in compounds, moreover in compounds with more than one equilibrium. In this work, these equilibria were studied for N-acyl and N-carbamoyl-3,4-dihydroxyquinoxalin-2(1H)-ones using mono- and bi-dimensional NMR experiments, at different temperatures. For both types of derivatives, the lactam form was the only tautomer detected. The results obtained from molecular modelling experiments agree with the experimental results. For the N-acyl derivative, the E isomer is the predominant, while for the N-carbamoyl derivative both geometric isomers are present in a similar ratio. The theoretical calculations allowed the signal assignment for each isomer from the chemical shift values estimated for both geometric isomers corresponding to the studied N-acyl and N-carbamoyl derivatives.
Thirty Years in the Design and Development of Cruzain Inhibitors
(2024-05-03) Jasinski, Gabriel; Martini, M. Florencia; Moglioni, ALbertina
Cruzipain is the principal protease of Trypanosoma cruzi, the etiological agent of Chagas disease. Since its discovery in the 1980s and the resolution of the crystal structure of cruzain (a truncated recombinant form of the enzyme) in 1995, this target has attracted the interest of many research groups for screening studies, structure-based and ligand-based drug design campaigns, which include peptide-like and non-peptide synthetic compounds. In this context, empirical and computational methods have proven to be valuable tools for the study of mechanisms of action, potential binding modes and structure-activity relationships for a diverse series of cruzain/cruzipain inhibitors. This paper, therefore, reviews some of the most relevant chemical groups reported as cruzain inhibitors over the last 30 years of research.
Molecularly imprinted polymers (MIPs) in sensors for environmental and biomedical applications : a review
(2021) Kadhem, Abbas J.; Gentile, Guillermina J.; Fidalgo de Cortalezzi, María M.
Molecular imprinted polymers are custom made materials with specific recognition sites for a target molecule. Their specificity and the variety of materials and physical shapes in which they can be fabricated make them ideal components for sensing platforms. Despite their excellent properties, MIP-based sensors have rarely left the academic laboratory environment. This work presents a comprehensive review of recent reports in the environmental and biomedical fields, with a focus on electrochemical and optical signaling mechanisms. The discussion aims to identify knowledge gaps that hinder the translation of MIP-based technology from research laboratories to commercialization.
Enhancement of the fouling resistance of zwitterion coated ceramic membranes
(2020) Storms, Max; Kadhem, Abbas J.; Xian, Shuting; Bernards, Matthew; Gentile, Guillermina J.; Fidalgo de Cortalezzi, María M.
Ceramic membranes suffer from rapid permeability loss during filtration of organic matter due to their fouling propensity. To address this problem, iron oxide ultrafiltration membranes were coated with poly(sulfobetaine methacrylate) (polySBMA), a superhydrophilic zwitterionic polymer. The ceramic-organic hybrid membrane was characterized by scanning electron microscopy (SEM) and optical profilometry (OP). Membranes with and without polySBMA coating were subjected to fouling with bovine serum albumin solution. Hydraulic cleaning was significantly more effective for the coated membrane than for the non-coated one, as 56%, 66%, and 100% of the fouling was removed for the first, second, and third filtration cycle, respectively. Therefore, we can highlight the improved cleaning due to an increased fouling reversibility. Although some loss of polymer during operation was detected, it did not affect the improved behavior of the tested membranes.
Interparticle effects in the cotransport of viruses and engineered nanoparticles in saturated porous media
(2021) Gentile, Guillermina J.; Blanco Fernández, María D.; Fidalgo de Cortalezzi, María M.
The effects of P25 TiO2 nanoparticles on the transport in saturated porous media of the bacteriophage PP7 was investigated. Two levels of ionic strength were considered, given by monovalent and divalent cations, Na+ and Ca2+. The viruses and the P25 particles were characterized with respect to size and surface charge, by dynamic light scattering and electron microscopy. The breakthrough curves were obtained for suspensions of each particle and both combined, using UV absorbance to quantify P25 and RT-qPCR for PP7. In the single transport experiments, P25 was retained, while the viruses mostly eluted the sand bed. However, in the cotransport experiments, retention increased for the virus and decreased for the TiO2 nanoparticles under high viral content, due to heteroaggregation among the colloids in the incoming suspension, electrostatic interactions, and ripening. The interparticle interactions were modeled by DLVO theory, resulting in agreement with the experimental observations, which highlights the electrostatic nature.
Nanotechnology and the environment
(2019) Gentile, Guillermina J.; Fidalgo de Cortalezzi, María M.
This chapter presents different phenomena that arise when nanomaterials reach the environment, with emphasis in water systems. Transformations on the surface of nanomaterials and nanoparticles because of adsorption of macromolecules and metals cations, as well as biological interactions alter their colloidal stability, originating in some cases homoaggregation or heteroaggregation, which in turn affects their fate and transport. Some engineering applications of nanomaterials are highlighted: as adsorbents, as enhancers of water filtration, providing antifouling, catalytic, and antibacterial activity, and as catalysts, giving special attention to photoactivity and to the removal of indoor air contaminants as volatile organic compounds.
Virus removal by iron oxide ceramic membranes
(2014) Fidalgo de Cortalezzi, María M.; Gallardo, María V.; Yrazu, Fernando; Gentile, Guillermina J.; Opezzo, Oscar; Pizarro, Ramon; Poma, Hugo R.; Rajal, Verónica B.
Nanoporous iron oxide ceramics were studied for the removal of virus contamination from water. Supported and unsupported iron oxide nanostructured hematite was fabricated by a green chemistry route from ferroxane nanoparticles. The material had a surface area of approximately 30 m2 /g and a mean pore size of 65 nm. Bacteriophage P22 was chosen as a model for human virus. The kinetics and equilibrium of the attachment process was investigated. P22 adsorption isotherms on iron oxide were described by the Freundlich equation. Batch experiments resulted in 1.5 LRVs. Removal proceeded rapidly for the first 7 h; next, a diffusion-limited stage occurred. Dynamic attachment experiments demanded extensive recirculation to achieve significant reduction levels. Up to 3 LRV were observed. The enhanced performance can be explained by the higher iron oxide area available and the facilitated access to inner porosity sites that were previously unavailable due to slow diffusion. The role of electrostatic interactions in the attachment mechanisms was confirmed by the dependence of the isotherm on the ionic strength of the suspension medium. P22 bacteriophage is expected to attach to the iron oxide by electrostatic forces up to a pH of 6.5. DLVO theory predicts moderately well the interaction energies between P22 particles themselves and between the phage and the ceramic. However, a slight underestimation of the P22–P22 repulsive forces was evident by comparison to the experimental data.
Electrostatic interactions in virus removal by ultrafiltration membranes
(2017) Gentile, Guillermina José; Cruz, Mercedes Cecilia; Rajal, Verónica Beatriz; Fidalgo de Cortalezzi, María Marta
Ultrafiltration membranes are increasingly used in potabilization to remove viral particles. This removal is controlled by electrostatic repulsion, attatchment and size exclusion. The effect of electrostatic interaction in virus filtration was investigated. Our work included characterization of bacteriophage PP7 and polyethersulfone membrane with respect to size and surface charge; the removal of this bacteriophage at laboratory scale by ultrafiltration membrane process and the mechanism and limitations were analyzed and discussed under DLVO and XDLVO theories. A partial removal of the bacteriophage was achieved; however, enhanced separation may be achieved considering that the process is affected by the aqueous matrix. The presence of divalent cations diminished the effectiveness of the procedure as opposed to monovalent cations and species with amphoteric behavior such as bicarbonate. DLVO and XDLVO predicted the interactions studied between bacteriophae PP7 and polyethersulfone membrane.
Comparative assessment of oxygen uptake rate of activated sludge and Escherichia coli exposed to nanomaterials
(2022-08) Aude Luppi, Vergenie E.; Oppezzo, Oscar J.; Fidalgo de Cortalezzi, María Marta
"The adverse effects of engineered nanomaterials (ENMs) on bacterial populations found in wastewater treatment plants (WWTPs) or natural systems have been studied for more than a decade, but conflicting evidence on the matter still makes it a subject of considerable concern. In this paper, the short-term exposure impact of titanium dioxide nanoparticles (nTiO2), carboxyl-functionalized multiwall carbon nanotubes (f-MWCNT), and zero-valent iron nanoparticles (nZVI) toward activated sludge and Escherichia coli (E. coli) was investigated through respiration inhibition experiments. Microorganisms were exposed to nanoparticle concentrations of 50, 100 and 200 mg/L (nTiO2, f-MWCNT) and 20, 50 and 100 mg/L (nZVI). The experiments showed that nTiO2 produced no inhibition in activated sludge or E. coli; up to 100 mg/L of nZVI did not inhibit the activated sludge respiration but 50 mg/L inhibited 24 ± 3% the respiration of E. coli and damaged its cell membrane. Activated sludge respiration was inhibited 17 ± 3% with 200 mg/L of f-MWCNT while for E. coli the inhibition was 36 ± 15% and the cell membrane was damaged with a 100 mg/L dose. Transmission electron microscopy (TEM) showed nTiO2-bacteria and nZVI-bacteria surface interaction while bacteria appeared punctured by f-MWCNT. E. coli was more susceptible than activated sludge to the nanomaterials and nZVI was more toxic than f-MWCNT for E. coli. These results demonstrated the absence of acute toxicity effects of the studied nanomaterials at those concentrations expected to occur in activated sludge facilities, and it would only be a concern in case of extremely high inputs, underscoring the resilience of WWTPs biological treatment."
On the use of espina corona gum as a polymeric additive in water-based drilling fluid
(2022-10) Villada, Yurany; Taverna, María Eugenia; Maffi, Juan M.; Giletta, Sebastián; Casis, Natalia; Estenoz, Diana
"The aim of this work is to evaluate the espina corona gum (ECG) as a sustainable viscosifier or filtration reducer additive in water-based drilling fluids (WBMs) as a potential replacement of guar gum (GG). ECG is a galactomannan isolated from leguminous seeds of Gleditsia amorphoides, trees that grow in South America with viscosifier properties and applications in the food area. ECG was characterized by FTIR, Z potential, intrinsic viscometry, TGA, and steady and oscillatory shear rheological analysis. Moreover, its effect on the main functional properties of WBMs was studied. Fluids containing bentonite (BT), polyanionic cellulose (PAC), GG or ECG were prepared, and rheological, filtration, thermal and structural properties were determined. In order to study the theoretical rheological behavior, several models such as power law, Sisko and Herschel-Bulkley were evaluated. The rheological studies revealed that WBMs containing ECG exhibit higher viscosities in comparison with those with GG. Herschel-Bulkley parameters indicated that the WBMs with high ECG concentration showed higher yield stress. In addition, the presence of ECG improves the thermal stability and filtration properties. The results indicate that ECG can be considered as an innovative, renewable and non-toxic alternative to partially or totally replace GG in WBMs."
Carbohydrate-derived polytriazole nanoparticles enhance the antiInflammatory activity of cilostazol
(2022-11-30) Rivas, M. Verónica; Musikant, Daniel; Díaz Peña, Rocío; Álvarez, Daniela; Pelazzo, Luciana; Rossi, Ezequiel; Martínez, Karina D.; Errea, María Inés; Pérez, Óscar E.; Varela, Óscar; Kolender, Adriana K.
"Poly(amide-triazole) and poly(ester-triazole) synthesized from d-galactose as a renewable resource were applied for the synthesis of nanoparticles (NPs) by the emulsification/solvent evaporation method. The NPs were characterized as stable, spherical particles, and none of their components, including the stabilizer poly(vinyl alcohol), were cytotoxic for normal rat kidney cells. These NPs proved to be useful for the efficient encapsulation of cilostazol (CLZ), an antiplatelet and vasodilator drug currently used for the treatment of intermittent claudication, which is associated with undesired side-effects. In this context, the nanoencapsulation of CLZ was expected to improve its therapeutic administration. The carbohydrate-derived polymeric NPs were designed taking into account that the triazole rings of the polymer backbone could have attractive interactions with the tetrazole ring of CLZ. The activity of the nanoencapsulated CLZ was measured using a matrix metalloproteinase model in a lipopolysaccharide-induced inflammation system. Interestingly, the encapsulated drug exhibited enhanced anti-inflammatory activity in comparison with the free drug. The results are very promising since the stable, noncytotoxic NP systems efficiently reduced the inflammation response at low CLZ doses. In summary, the NPs were obtained through an innovative methodology that combines a carbohydrate-derived synthetic polymer, designed to interact with the drug, ease of preparation, adequate biological performance, and environmentally friendly production."
The organic chemistry behind the recycling of poly(bisphenol-A carbonate) for the preparation of chemical precursors: A review
(2022-07) Gilbert, E.; Polo, Mara Lis; Maffi, Juan M.; Guastavino, Javier Fernando; Vaillard, Santiago Eduardo; Estenoz, Diana
"Production and consumption of poly(bisphenol-A carbonate) resins are seeing a worldwide increase. However, their usage lifetimes are short and their final disposition as landfills pose environmental and health risks, due to the release of toxic bisphenol-A (BPA). The development of alternative recycling routes is thus becoming subject of increasing interest. In this review, the main recycling processes of poly(bisphenol-A carbonate) are described and critically compared, with special focus on the chemical mechanisms. While mechanical recycling is possible, the end products are restricted only to polymer blends, whose main mechanical properties decrease with each compounding cycle. In turn, chemical recycling can produce BPA monomer and a variety of byproducts that can be used in different industries, including the polymeric field, as synthesis reagents and precursors. The operation conditions of each method are reviewed, as well as the different results obtained in terms of product yield, composition, selectivity and reaction times. Reaction mechanisms are described in detail and a view on the usability of each end product is offered."
Kinetic and chemorheological modeling of thermosetting polyurethanes obtained from an epoxidized soybean oil polyol crosslinked with glycerin
(2022-10) Armanasco, Franco; Chiacchiarelli, Leonel Matías; D'hers, Sebastián
"Thermosetting polyurethanes were obtained using an aromatic isocyanate and a hydrophobic polyol formulation obtained from epoxidized soybean oil (ESO) crosslinked with glycerin. A systematic DSC analysis of the effect of catalyst type, crosslinker concentration, isocyanate index and ESO crystallization on cure kinetics was conducted. The combination of a stannic catalyst at 0.2 wt% and glycerin at 20 wt% produced a cure kinetics governed by an autocatalytic heat flow where vitrification played a key role in the formation of chemical bonds. The evolution of Tg as a function of conversion, which followed Di-Benedetto's predictions, supported the hypothesis that vitrification was a preponderant phenomenon during cure. Dynamic Mechanical Analysis (DMA) of a post-cured sample revealed a Tg centered at 220°C, whereas quasi-static flexural mechanical tests shown a flexural modulus of 2.14 GPa and a flexural strength of 99.4 MPa. Rheological experiments at isothermal conditions supported the hypothesis that vitrification played a key role in the evolution of apparent viscosity. A master model using Kim-Macosko equations was obtained for the proposed formulation. The results presented in this work will serve to further extend the use of biobased polymers applied in the polymer composite industry."
A sensitivity analysis and a comparison of two simulators performance for the process of natural gas sweetening
(2016-04) Gutiérrez, Juan Pablo; Benítez, Leonel A.; Ale Ruiz, Elisa Liliana; Erdmann, Eleonora
"Chemical processes simulation is an important instrument for the design, optimization and control of industrial plants. Simulation cases can be accomplished with relatively low costs and the absence of risks for the operators. However, the precision of the results depends on the similarity between the simulation performed and the process considered. In this article, two simulators, Aspen Hysys V8.6 and Aspen Plus V8.6, are employed to simulate the process of natural gas sweetening using diethanolamine (DEA). Additionally, a parametric sensitivity analysis is performed to define the optimal operative range for the process. The required data and the conditions of the operating units are taken from a gas conditioning plant in northern Argentina. Finally, a comparison between the block of obtained results from both simulations is also detailed."
A novel combination of experimental design and artificial neural networks as an analytical tool for improving performance in thermospray flame furnace atomic absorption spectrometry
(2016-02) Morzan, Ezequiel; Stripeikis, Jorge; Goicoechea, Héctor; Tudino, Mabel Beatriz
"In this work, we present the combined effect of artificial neural networks (ANN) and experimental design as a suitable analytical tool for improving the performance of thermospray flame furnace atomic absorption spectrometry (TS-FFAAS) using Mg as leading case. To this end, mixtures of different amounts of methanol, ethanol, and i-propanol in water were assayed as carriers at different flow rates and different flame stoichiometries (air/acetylene ratios). Different levels of these variables determined the experimental domain, consisting in a cube which was divided into eight identical cubical regions that allowed increase in the number of available experimental points. A Box–Behnken design (BBD) was employed in each one of the regions. The name Multiple Box–Behnken design (MBBD) was given to this new approach. Then, the features of ANN were exploited to find the optimum conditions for conducting Mg determination by TS-FFAAS. The prediction capability of ANN was examined and compared to the least-squares (LS) fitting when applied to the response surface method (RSM). The suitability of the new approach and the implications on TS-FFAAS analytical performance are discussed."
Imidazo[2,1-b]thiazole carbohydrate derivatives: synthesis and antiviral activity against Junin virus, agent of Argentine hemorrhagic fever
(2011-01) Barradas, José Sebastián; Errea, María Inés; D´Accorso, Norma B.; Sepúlveda, Claudia Soledad; Damonte, Elsa Beatriz
"Herein, we describe the syntheses of 3,5-disubstituted imidazo[2,1-b]thiazole. The cyclization step was performed in two different conditions by using either thermal or microwave heating. Comparing the results of both methodologies, we found that the microwave assistance is an improved alternative to obtain this family of heterocyclic compound. Compounds were first evaluated for cytotoxicity in Vero cells by MTT method and then, the antiviral activity was assayed by a virus yield inhibition assay in the range of concentrations lower than the corresponding CC50, using JUNV strain IV4454 as the model system. The most active compounds (3 and 4), showed a level of antiviral activity against JUNV in monkey Vero cells better than the reference substance ribavirin. Then, they are promising lead compound for further analysis and characterization to establish their therapeutic potential against hemorrhagic fever viruses."
On the evolution of particle size distributions during the bulk synthesis of high-impact polystyrene using PBM: Towards morphology and phase inversion prediction
(2022-01-16) Maffi, Juan M.; Estenoz, Diana
"The mechanism of the phase inversion (PI) process that occurs during the bulk polymerization of High Impact Polystyrene (HIPS) is studied in this article. Transmission electron micrographs (TEM) were obtained for different operating conditions, varying initiator concentration, temperature, and stirring speed from a previous work. Particle size distributions were retrieved from such micrographs, and were compared to theoretical predictions. To this end, a population balance model, coupled with a heterogeneous polymerization module, was developed. The evolution of particle growth, break-up and coalescence is discussed to assess the breakage/coalescence imbalance that is thought to occur at the inversion point. Results indicate that a different criterion for PI seems to be needed in this system."
Detection of progesterone in aqueous samples by molecularly imprinted photonic polymers
(2022-04) Qasim, Sally; Hsu, Shu-Yu; Rossi, Ezequiel; Lin, Chung-Ho; Polo Parada, Luis; Fidalgo de Cortalezzi, María Marta; Salahshoor, Zahra
"A label-free molecular imprinted polymer (MIP) sensor was fabricated for the detection of progesterone in aqueous solutions, by polymerization inside the void spaces of colloidal crystals, which gave them photonic properties. The prepolymerization mixture was prepared from acrylic acid as the functional monomer, ethylene glycol as the cross-linker agent, ethanol as solvent, and progesterone as the imprinted template. After polymerization, the colloidal crystal was removed by acid etching and the target eluted with a solvent. Material characterization included as follows: attenuated total reflectance-Fourier-transform infrared spectroscopy, dynamic light scattering, swelling experiments, and environmental scanning electron microscopy. MIPs were investigated by equilibrium binding, kinetics experiments, and UV–visible spectra to investigate Bragg diffraction peak shift that occurs with the rebinding at different progesterone concentrations in deionized water and 150-mM NaCl solutions. The MIP response was investigated with progesterone concentration in the 1–100 μg L−1 range, with LOD of 0.5 μg L−1, reaching the detected range of hormone in natural waters. Furthermore, hydrogel MIP films were successfully tested in various real water matrices with satisfactory results. Moreover, the MIP film exhibited good selectivity toward the progesterone hormone evidenced by a larger response than when exposed to structurally similar molecules. Computational studies suggested that size along with surface potential influenced the binding of analog compounds. Due to their ease of use and low cost, the sensors are promising as screening tools for the presence of progesterone in aqueous samples."
Preparation of water insoluble carboxymethylated bacterial cellulose with maximum lead retention capacity
(2021-06) Montoya Rojo, Úrsula; Rossi, Ezequiel; Cerrutti, Patricia; Errea, María Inés; Foresti, María Laura
"Chemical modification of bacterial cellulose (BC) through carboxymethylation was carried out to prepare a low-cost highly stable lead adsorbent material (CMBC). Aiming to maximize its adsorption capacity, the effect of the carboxymethylation extent conferred to BC on the lead retention ability of the insoluble CMBC products obtained was studied. Results evidenced a strong linear correlation between the lead retention capacity of CMBC samples and their degree of substitution, highlight-ing a key role on the biobased adsorbents performance of the amount of negatively charged carboxylate groups available for an ion-exchange-governed lead adsorption process. Proper tuning of the carboxymethylation extent conferred to BC thus allowed maximizing its lead adsorption capacity, reaching values (i.e.127.2 mg g−1) that doubled those previously reported."
In-situ thermal aging of biobased and conventional rigid polyurethane foams nanostructured with bacterial nanocellulose
(2021-11-02) Diaz, Tomás Joaquin; Cerrutti, Patricia; Chiacchiarelli, Leonel Matías
"The incorporation of nanofillers and the use of biobased polyols might have a deleterious effect on the aging performance of rigid polyurethane foams (RPUFs) applied in the insulation and marine industries. To study this, RPUFs obtained from petroleum based (RPUF) and castor oil (RPUFRIC) polyols were nanostructured with bacterial nanocellulose (BNC) up to 0.3 wt%. Water immersion experiments revealed that the normalized water absorption (NWA) at the steady state was not affected by lower BNC contents (<0.2 wt%). Higher BNC contents caused a complex effect on post-cure and foaming, generating cell size expansion as well as shrinkage. In-situ DMA aging analysis revealed that the specific storage modulus (E'sp) under flexural conditions of the RPUFRIC and RPUF decreased by a maximum amount of 7.27% and 6.19%, respectively. The effect of BNC on the E'sp was negligible, expect for the case of the RPUF, where higher BNC concentrations (>0.2 wt%) caused a decrease of up to 13.69%. The previous results reinforce the hypothesis that the incorporation of BNC in both conventional and biobased polyurethane systems do not cause significant changes on the aging performance of the resulting foams, provided that low BNC concentrations are employed."

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