DSpace Repository :: Browsing by Author "Rossi, Ezequiel"

Browsing by Author "Rossi, Ezequiel"

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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."
Carboxymethylated bacterial cellulose: an environmentally friendly adsorbent for lead removal from water
(2018-12) Rossi, Ezequiel; Montoya Rojo, Úrsula; Cerrutti, Patricia; Foresti, María Laura; Errea, María Inés
"Carboxymethylated bacterial cellulose (CMBC) was synthesized under controlled reaction condition to provide a material with a degree of substitution (DS) that guarantees that the characteristic water insolubility of cellulose is retained (DS = 0.17). The CMBC synthesized was fully characterized by conductometric titration, infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis and solubility assays. The suitability of the produced CMBC for lead removal from water was evaluated. Experimental isotherm data were fitted to different models of sorption isotherms: Langmuir, Freundlich, Dubinin-Radushkevich, and Frumkin, with Langmuir equation resulting in the best fit. Kinetic data were also adjusted to pseudo-first-order and pseudo-second-order models and results undoubtedly showed that the pseudosecond-order kinetic equation was the one that most appropriately described the lead adsorption of CMBC, indicating that lead is adsorbed on CMBC predominantly by chemical interaction. The breakthrough curve was fitted to different models: Bohart-Adams, Clark and Modified Dose-Response, being the Bohart-Adams equation the one that gave the best fit. Desorption studies were carried out in order to know the technical feasibility of the reuse of CMBC. Almost 96% of the retained lead was eluted in just 20 mL, and the CMBC lifetime was over 50 adsorption/desorption cycles. Overall, results obtained suggest that the CMBC herein synthesized may result in an alternative economic and environmentally friendly lead adsorbent for water treatment."
Chitosan: from organic pollutants to high-value polymeric materials
(2017) Errea, María Inés; Rossi, Ezequiel; Goyanes, Silvia Nair; D'Accorso, Norma Beatriz
"...chitosan has proved to be versatile for so many industrial applications and its versatility is the main value of this polymer. However, the lability at acidic pH of chitosan is a limiting factor that affects mainly its industrial implementation for the removal of metallic anions from water. In addition, the physical and mechanical properties may vary between two manufacturing batches due to the characteristic polydispersity of chitosan with respect to molecular weight and degree of acetylation. This variation could affect the industrial process and in some cases, when strict specifications are requested (e.g., drug delivery), increase the final cost of the product because a purification step prior to use is required. Briefly, despite of the disadvantages mentioned before, due to its great versatility, its nontoxicity, its biodegradability, and the fact that it has a renewable resource, the industrial interest in chitosan and its application has been increasing remarkably in the last years."
Detection of chlorantraniliprole residues in tomato using field-deployable MIP photonic sensors
(2021-02) Rossi, Ezequiel; Salahshoor, Zahra; Ho, Khanh-Van; Lin, Chung-Ho; Errea, María Inés; Fidalgo de Cortalezzi, María Marta
"A photonic sensor based on inversed opal molecular imprinted polymer (MIP) film to detect the presence of chlorantraniliprole (CHL) residue in tomatoes was developed. Acrylic acid was polymerized in the presence of CHL inside the structure of a colloidal crystal, followed by etching of the colloids and CHL elution. Colloidal crystals and MIP films were characterized by scanning electron microscopy and FT-IR, confirming the inner structure and chemical structure of the material. MIP films supported on polymethylmethacrylate (PMMA) slides were incubated in aqueous solutions of the pesticide and in blended tomato samples. The MIP sensor displayed shifts of the peak wavelength of the reflection spectra in the visible range when incubated in CHL concentrations between 0.5 and 10 μg L−1, while almost no peak displacement was observed for non-imprinted (NIP) films. Whole tomatoes were blended into a liquid and spiked with CHL; the sensor was able to detect CHL residues down to 0.5 μg kg−1, significantly below the tolerance level established by the US Environmental Protection Agency of 1.4 mg kg−1. Stable values were reached after about 30-min incubation in test samples. Control samples (unspiked processed tomatoes) produced peak shifts both in MIP and NIP films; however, this matrix effect did not affect the detection of CHL in the spiked samples. These promising results support the application of photonic MIP sensors as an economical and field-deployable screening tool for the detection of CHL in crops."
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."
Polímeros modificados químicamente como agentes de captura de metales en agua
(2020-04-21) Rossi, Ezequiel; Errea, María Inés; Fidalgo de Cortalezzi, María Marta
"En el marco del interés por el tratamiento de aguas contaminadas, el objetivo general de este Trabajo de Tesis fue obtener materiales para la remoción de metales pesados de sistemas acuosas, mediante la modificación química de polímeros. Específicamente, se presentan los productos obtenidos al modificar celulosa, quitosano y poli (cloruro de vinilbencilo) (PCVB), la caracterización de los nuevos materiales y los estudios de captura de metales a los que fueron sometidos."
Preparation and characterization of nanoencapsulated synthetic soybean oil derivative-an abundant and environmentally friendly phase change material-heat transfer analysis and applications
(2020-10) Bergamo, Jorge; Rossi, Ezequiel; Maffi, Juan M.; De Angelis, Laura; Errea, María Inés
"The thermal properties of a phase change material (PCM), together with its environmental health risks and natural abundance are important aspects to consider when choosing one for a domestic application. In this work, a soybean oil derivative, which comes from one of the most abundant crops on Earth, is proposed as PCM. A heat transfer model was developed to compare the performance of the proposed PCM, under the same boundary and initial conditions, with other materials reported in literature that have well-known disadvantages in terms of flammability, renewability, abundance and environmental care. Results showed that its performance was as good as theirs. Nanocapsules of the PCM coated with TiO2 were prepared and characterized physical, thermal and morphologically. Thermal studies were carried out in a device designed and constructed simulating a water heater, and a reduction of about 70% of the PCM phase thermal resistance due to the TiO2 shell was observed. Furthermore, the calculated thermal energy stored in the device filled with nanoencapsulated PCM was 10.6% higher with respect to the blank, and the total cooling time of the water was increased by over 18% thanks to the PCM."
Preparation of an environmentally friendly lead adsorbent. A contribution to the rational design of heavy metal adsorbents
(2020-10) Rossi, Ezequiel; Ávila Ramírez, Jhon Alejandro; Errea, María Inés
"This work described the preparation and characterization of water insoluble chitosan derivatives as lead adsorbents. In highly regioselective reactions, N-substituted crosslinked chitosan derivatives were obtained by crosslinking native chitosan with mucic and adipic acid (a polyhydroxylated and a non-functionalized diacid of the same length chains). The crosslinking degree of the chitosan modified with adipic acid was significantly higher than that crosslinked with mucic acid (0.446 and 0.316, respectively), while the degree of substitution was almost the same (approximately 80 %). Lead adsorption isotherms were constructed at different temperatures and adjusted to well-known models, obtaining the best fit to the experimental data with Langmuir model. The lead adsorption capacity of new materials was greater than many of the adsorbents described in literature (76.3 and 69.7 mg g−1 for chitosan modified with mucic and adipic acid, respectively). Moreover, thermodynamic parameters were calculated, and results showed that the lead adsorption on the derivatives was spontaneous, exothermic, and governed by chemical interaction. Besides, kinetic studies were performed and adjusted to well-known models. The pseudo-second order kinetic equation was the one that most appropriately described the lead adsorption on the new materials. Results were consistent with the strong electrostatic attraction established between the lead cations and the free carboxylate groups of the derivatives."
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."
Selective determination of Cr (VI) by on-line solid phase extraction FI-SPE-FAAS using an ion exchanger resin as sorbent: an improvement treatment of the analytical signal
(2017-01) Rossi, Ezequiel; Errea, María Inés; Fidalgo de Cortalezzi, María Marta; Stripeikis, Jorge
"A flow injection (FI) technique based on an on-line solid phase extraction (SPE) coupled with flame atomic absorption spectroscopy (FAAS) to selectively quantify chromium (VI) in the presence of chromium (III) was developed. An anion exchanger was used as solid sorbent and the detection limit found was two order of magnitude lower than that expected quantifying by FAAS. Until now, quantitative determinations in FAAS were carried out by measuring the height of the peaks rather than their area. In our hands, the software was reconfigured and the area under the peaks could be measured. Considering area instead of height, the enhancement factor increases from 6.7 to 360 (approx. 54 times) giving a detection limit of 0.034 μg·L − 1 , lower than that obtained using much more expensive instruments such as electrothermal atomic absorption spectrometry (ETAAS) or inductively coupled plasma-atomic emission spectrometry (IPC-AES), greatly enhancing the potential of this methodology for future use in speciation studies. The operation conditions were: pH 3, sample loading 50 mL·min − 1 , elution flow rate 7.5 mL·min − 1 . The anion exchanger lifetime was over 100 adsorption/desorption cycles. Anions commonly present in natural aqueous systems did not interfere in the chromium retention. The accuracy was validated using a certified reference material (Fluka Analytical, QC3453)."

Browsing by Author "Rossi, Ezequiel"

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