Acid hydrogel matrixes as reducing/stabilizing agent for the in-situ synthesis of Ag-nanocomposites by UV irradiation: PH effect

Synthetic methods to obtain Ag-nanocomposites are widely studied in order to produce antimicrobialmaterials without using harmful agents for possible applications in biologic systems. In this way, thenanocomposites could be able to apply in biomedicine area avoiding going through exhaustiveprocesses of purification. Biocompatible hydrogel based on N-isopropylacrylamide (NIPAM)copolymerized with different proportions of methacrylic acid (MAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), were proposed as matrixes of Ag-nanocomposites. A comprehensive studyof the physicochemical behavior, reducing and stabilizing character of the matrixes were carried out atpH 2 and 7. Hydrogel nanopores were used as photoreducing of Ag+ ions and stabilizing of Agnanoparticles(Ag-NPs) at the same time. Most of the matrixes showed high reducing character atpH 7 while at pH 2 it was significantly reduced. Photoreducer character at pH 7 increased with MAAco-monomer concentration and Ag-NPs sizes of 4?5 nm were obtained. In addition, it wasdemonstrated that acidic co-monomers favor the stabilization of Ag-NPs avoiding agglomerations. Itwas possible to conclude that the photoreduction reaction takes mainly place at pH 7 when nonbonding electron pairs from carboxylic and amide groups of the matrix are available. Therefore,biocompatible and antimicrobial nanocomposites can be easily synthesized without using damagingadditives(reducer, solvent) and be applied in biomedicine.Fil: Broglia, Martin Federico. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Balmaceda, Ivana. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Carrizo, Florencia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Barbero, César Alfredo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Rivarola, Claudia Rosana. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentin

One step lithography of polypyrrole

Large areas of polypyrrole (PPy) thin films deposited onto inert polymeric substrates are structured by direct laser interference patterning (DLIP). Several square millimeter areas could be produced with one single (10âns) pulse, at room temperature and atmospheric pressure. Nanometric arrays of lines (>600ânm) or grids of PPy deposited on dielectric polymers polypropilene or polypirrol (PP or PE) are fabricated by DLIP at 355ânm. The period of the lines structures, measured by white light interferometry (WLI), is 3.5âÂμm. Regular structures are analyzed using scanning electron microscope (SEM) and a focus ion beam (FIB) tomography. It is shown that only the PPy film is structured while the PP or PE substrate remains unaltered. Fourier transform infrared spectroscopy (FTIR) and UV-vis spectroscopy, permit to ensure that PPy chemical structure remains unaltered after the structuration process. The width of PPy lines can be tailored by controlling the fluence of the laser beam. Contact angle measurement shows that the wettability is affected by the structuring, making the surface more hydrophobic. The structuring technique seems to be suitable for the fabrication of PPy regular structures over various substrates.Fil: Acevedo, Diego Fernando. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Frontera, Evelina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Broglia, Martin Federico. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Mücklich, Frank. Universitat Saarland; AlemaniaFil: Miras, Maria Cristina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Barbero, César Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin

Cuando de leer y escribir se trata. Generando puentes para el ingreso a una nueva cultura en carreras de Ingeniería

En este trabajo, cuyo eje es una experiencia en curso en la materia Química para el primer año de las carreras de Ingeniería de la FI-UNRC, nos hemos referido a las dificultades de los estudiantes y al desafío que las mismas suponen a la enseñanza universitaria. En este apartado, queremos referirnos a los aprendizajes y a las reflexiones que como docentes nos suscita tal experiencia.Fil: Alcoba, Marcelo Patricio. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; ArgentinaFil: Amieva, Rita Lilian. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; ArgentinaFil: Miskovski, Viviana Rita. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; ArgentinaFil: Broglia, Martin Federico. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentin

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Triplet state quenching of phenosafranine dye by indolic compounds studied by transient absorption spectroscopy

The interaction of the triplet state of the synthetic dye phenosafranine (3,7-diamino-5-phenylphenazinium chloride) with indolic compounds of biological relevance was investigated in water by means of laser flash photolysis. The rate constants for the triplet quenching were determined. The quenching process may be explained by an electron transfer from the indole to the dye in its triplet state. The rate constants present a typical dependence of an electron transfer process with the one-electron oxidation potential of the indole. Indole-3-acetic acid and its homologous indole propionic and indole butyric acids are the most effective quenchers with rate constants reaching the diffusion limit. Rate constants for indole itself, tryptophan and indole-3 carboxylic acid are one order of magnitude lower. The electron transfer nature of the quenching reaction is further confirmed by the detection of the semi-reduced form of the dye by its transient absorption. The absorption coefficients of the transient species were estimated, and the quantum yield of the charge separation process was determined. The efficiency of formation of radical species is between 60 and 90% of the triplets intercepted.Fil: Broglia, Martin Federico. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Previtali, Carlos Mario. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bertolotti, Sonia Graciela. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Excited states quenching of phenosafranine dye by electron donors

The quenching of the excited singlet and triplet states of phenosafranine by aromatic amines, methoxybenzenes and triethanolamine was investigated in acetonitrile and methanol. The rate constants for the aromatic quenchers present a typical dependence of an electron transfer process with the one-electron redox potential of the donor. A Rehm-Weller correlation is obtained with the driving force. The fitting parameters are very similar in both solvents. The electron transfer nature of the quenching reaction is further confirmed by the detection of the radical cations of the quenchers and the semireduced form of the dye in laser flash photolysis experiments. The absorption coefficients of the transient species were estimated, and the quantum yield of the charge separation process was determined.Fil: Broglia, Martin Federico. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Bertolotti, Sonia Graciela. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Previtali, Carlos Mario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin

Highly effective antimicrobial nanocomposites based on hydrogel matrix and silver nanoparticles: Long-lasting bactericidal and bacteriostatic effects

Antimicrobial nanocomposites (NCs) are being used as an alternative antibacterial therapy for killing antibiotic-resistant pathogenic bacteria. The NCs are made of Ag nanoparticles (AgNPs) inside biocompatible hydrogel matrixes. The NCs were synthesized by the absorption of AgNO3 solution into a hydrogel matrix, followed by UV light irradiation, without using additional toxic reactants. The hydrogels used as matrixes are based on N-isopropylacrylamide (NIPAM) and copolymers with different functional groups: 2-acrylamide-2-methylpropanesulfonic acid (AMPS), N-hydroxyethylacrylamide (HEAA) and (3-acrylamidepropil)trimethylammonium chloride (APTMAC). Neutral, anionic and cationic groups were added to the matrixes in order to study their effects on the release of antibacterial species. The NCs were characterized by UV-visible spectroscopy and transmission electronic microscopy. The kinetics of the release of Ag+ ions from the NCs were followed by UV-visible spectroscopy at 300 nm. Biological experiments were based on the plate count method and agar diffusion testing against Pseudomonas aeruginosa. The bacterial death rate using the NCs is higher than when PNIPAM and nanoparticles in solution are used and seems to be related to the large amount of AgNPs contained inside the gels. In all cases, inhibition and diffusion halos were observed upon the exposure of bacterial cultures on agar to NC discs. The presence of both halos confirmed the bactericidal and bacteriostatic effects of the NCs. The reusability (prolonged use) of the materials was demonstrated until the Ag-NP content was exhausted. The NCs with a higher antibacterial capacity are based on a PNIPAM-co-6%APTMAC matrix. It was demonstrated that these NC materials have the capacity to maintain an aseptic/antiseptic zone for 7 to 15 days.Fil: Monerris, Melisa Jimena. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Broglia, Martin Federico. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Yslas, Edith Inés. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Barbero, César Alberto. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rivarola, Claudia Rosana. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Controlled release systems of natural phenolic antioxidants encapsulated inside biocompatible hydrogels

Encapsulated systems of antioxidants control the bioavailability in foods, enhancing and conserving their quality. Biocompatible hydrogels based on poly-(N-isopropylacrylamide) (PNIPAM) and copolymers, crosslinked with N,N-methylenebisacrylamide (BIS), are proposed as scaffold materials of antioxidants. Hydrogels are synthesized by copolymerization of NIPAM and N-hydroxyethyl acrylamide (HEAA) or N-acryloyl-tris-(hydroxymethyl) aminomethane (NAT) co-monomers. In order to compare the behaviors of delivery systems, the same proportions of co-monomers are added. The studied phenolic compounds (PHc) are: 2-(2-hydroxyethyl) phenol (2-OH) and its isomer 4-(2-hydroxyethyl) phenol (4-OH) or tyrosol, and ferulic acid (FAc). By UV-visible spectroscopy, the partition coefficients of antioxidants in matrix/aqueous medium are determined. To describe the behavior of each controlled release systems, new kinetic parameters are defined: initial concentration of loaded drug (ICLD), the maximum molar concentration of released drug from hydrogel (Ceq) and the elapsed time for releasing the 50% and 100% of loaded substrate, among others. Determined Pc values indicate that the intramolecular interactions between PHc and hydrogel increase with OH group amount inside matrix. The release kinetics of PHc from hydrogels are different depending on substrate-matrix intermolecular interactions. A long-time release could be favored by a more hydrophilic matrix such as PNIPAM-co-8%NAT, and quick release is expected by less hydrophilic matrixes as PNIPAM or PNIPAM-co-8%HEAA. Free and encapsulated PHc show antioxidant activity against photogenerated reactive oxygen species in aqueous solution.Fil: Casadey, Rocio Guadalupe. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; ArgentinaFil: Broglia, Martin Federico. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Barbero, César Alfredo. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto; ArgentinaFil: Criado, Susana Noemi. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto; ArgentinaFil: Rivarola, Claudia Rosana. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentin

Photophysical properties of safranine and phenosafranine. A comparative study by laser flash photolysis and laser induced optoacoustic spectroscopy

The triplet quantum yield of the dyes safranine and phenosafranine was determined in methanol and acetonitrile by laser flash photolysis (LFP) and laser induced opto-acoustic spectroscopy (LIOAS). The excited singlet properties of both dyes were also determined in the two solvents. The LFP determination of the triplet yield was carried out by actinometric determination of the product ΦTεT and independent estimation of εT by the singlet depletion method and by energy transfer using anthracene as energy donor. The results of the three methodologies coincide within the experimental error. The values of ΦT are in the range 0.21-0.50, and in the case of phenosafranine are considerably higher than those previously reported in the literature. An interesting outcome is that the results of LIOAS determination agree with those of LFP within the confidence interval.Fil: Broglia, Martin Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Gómez, María L. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Bertolotti, Sonia Graciela. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Montejano, Hernan Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Previtali, Carlos Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin