Díaz Baños, F. Guillermo

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Díaz Baños, F. Guillermo

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Díaz Baños, F. Guillermo

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Universidad de Murcia. Departamento de Química Física

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Open Access
Description and comparative study of physico-chemical parameters of the teleost fish skin mucus.
(SAGE Publications, 2015-07-01) Guardiola Abellán, Francisco Antonio; Cuartero, María; Collado-González, Mar; Arizcún, Marta; Díaz Baños, F. Guillermo; Meseguer, José; Esteban Abad, María de los Ángeles; Biología Celular e Histología
The study of mucosal surfaces, and in particular the fish skin and its secreted mucus, has been of great interest recently among immunologists. Measurement of the viscosity and other physico-chemical parameters (protein concentration, pH, conductivity, redox potential, osmolality and density) of the skin mucus can help to understand its biological functions. We have used five marine species of teleost: gilthead seabream (Sparus aurata L.), European sea bass (Dicentrarchus labrax L.), shi drum (Umbrina cirrosa L.), common dentex (Dentex dentex L.) and dusky grouper (Epinephelus marginatus L.), all of them with commercial interest in the aquaculture of the Mediterranean area. Mucus showed a direct shear- and temperature-dependent viscosity, with a non-Newtonian behavior, which differed however between two groups: one with higher viscosity (D. labrax, U. cirrosa, D. dentex) and the other with lower viscosity (S. aurata, E. marginatus). In addition, there was a clear interrelation between density and osmolality, as well as between density and temperature. Taking into account that high values of viscosity should improve the barrier effect against pathogens but low values of viscosity are needed for good locomotion characteristics, our results may help elucidate the relationship between physico-chemical and biological parameters of skin mucus, and disease susceptibility.
Open Access
Chitosan as stabilizing agent for negatively charged nanoparticles
(Elsevier, 2016-12-24) Collado-González, Mar; García Montalbán, Mercedes; Peña-García, Jorge; Pérez-Sánchez, Horacio; Víllora Cano, Gloria; Díaz Baños, F. Guillermo; Biología Celular e Histología
Chitosan is a biocompatible polysaccharide with positive Z potential which can stabilize negative charged nanoparticles. Silk fibroin nanoparticles and citrate gold nanoparticles, both with negative Z potential, but they form aggregates at physiological ionic strength. In this work, we study the behavior of chitosan in solution when the ionic strength of the medium is increased and how the concentration of chitosan and the proportion of the two components (chitosan and AuNP or SFN) significantly affect the stability and size of the nanocomposites formed. In addition to experimental measurements, molecular modeling were used to gain insight into how chitosan interacts with silk fibroin monomers, and to identify the main energetic interactions involved in the process. The optimum values for obtaining the smallest and most homogeneous stable nanocomposites were obtained and two different ways of organization through which chitosan may exert its stabilizing effect were suggested.
Open Access
Size-exclusion chromatography of macromolecules: a brief tutorial overview on fundamentals with computational tools for data analysis and determination of structural information
(MDPI, 2025-02-22) Henández-Cifre, José Ginés; Collado-González, Mar; Díaz Baños, F. Guillermo; García de la Torre, José; Química Física; Ingeniería Química; Biología Celular e Histología
Size-exclusion chromatography (SEC) is presently a widely used and very informative technique for the characterization of macromolecules in solution. Beyond the first implementations of SEC—which required cumbersome column calibrations and were mainly intended for the determination of molecular weights—the modern SEC approach involving multiple detectors (md-SEC) is based on solution properties such as intrinsic viscosity and light scattering. Thus, md-SEC enables the direct and more efficient determination of molecular weights, as well as the determination of relationships between property and molecular weight, which can be quite useful in structural studies. Here, we first present a review of the fundamental aspects of the dilute-solution properties of macromolecules—particularly the differential refractive index, intrinsic viscosity, and scattering-related properties—on which the various detectors involved in md-SEC are based. Then, we developed SECtools, a suite of public-domain, open-source computer programs, which allow for the full analysis of md-SEC chromatograms. These analyses range from just the recorded raw signals (mV) of the detectors to a full determination of molecular weight averages and distributions. The use of these programs is illustrated through experimental studies using various samples.
Open Access
Complex polysaccharide-based nanocomposites for 2 oral insulin delivery
(MDPI (Basel, Switzerland), 2020-01-15) Collado-González, Mar; Freitas, Alessandra R.; Santos, Ana Claudia; Ferreira, Nuno F.; Ferreri, Maria Cristina; Sequeira, Joana A.D.; Díaz Baños, F. Guillermo; Víllora Cano, Gloria; Veiga, Francisco; Ribeiro, Antonio; Carissimi, Guzmán; Química Física
Polyelectrolyte nanocomposites rarely reach a stable state and aggregation often occurs. Here, we report the synthesis of nanocomposites for the oral delivery of insulin composed of alginate, dextran sulfate, poly-(ethyleneglycol) 4000, Poloxamer 188®, chitosan, and BSA. Chitosan seems to be essential for the final size of the nanocomposites. When the chitosan concentration used in the synthesis is 10-4 gcm-3, nanocomposites, microcomposites and milimetric composites are obtained. Reducing the chitosan concentration to 10-5 or 10-7 gcm-3 yields nanocomposites of 400-600 nm or 800-900 nm hydrodynamic diameter, respectively, measured by DLS. According to our results, the molecular weight of chitosan has little influence on the size of the composites. The enhanced stability of the newest nanocomposites synthesized was assessed with LUMiSizer®. The rounded shapes of the nanocomposites were confirmed by scanning electron microscopy. Analysis by HPLC revealed that, after loaded with insulin, about 80% of the drug was released from our nanocomposites.
Open Access
Assessing chemical toxicity of ionic liquids on Vibrio ﬁscheri: Correlation with structure and composition
(Pergamon – Elsevier Science Ltd, 2016-04-11) Hidalgo, Juana M; García Montalbán, Mercedes; Salinas Hidalgo, María Dolores; Collado-González, Mar; Díaz Baños, F. Guillermo; Víllora Cano, Gloria; Biología Celular e Histología
One of the most important properties of the ionic liquids (ILs) is their non-volatility. However, they are wide soluble in water. For this reason, they can be released to aquatic ecosystems and to contribute to water pollution. Nevertheless, toxicological data related to ionic liquids is scarce in literature because of the great number of possible ionic liquids synthesized. The present work reports the toxicity of twenty-nine imidazolium-, pyridinium- and ammonium-based ionic liquids towards the luminescent bacteria Vibrio fischeri. Some of the effects analyzed on the toxicity have been the type of anion, the length of the alkyl chain of the cation, the cation core and the presence of a functionalized side chain in the cation. These results have showed that the main influence on the toxicity of the ILs is the alkyl chain length. A Quantitative Structure-Activity Relationships (QSAR) method has been used to validate our results obtaining a very good agreement.
Open Access
Aggregation behaviour of gold nanoparticles in presence of chitosan
(Springer, 2015-06-13) Fernández Espín, Vanesa ; Pamies, Ramón ; García de la Torre, José; García Montalbán, Mercedes; collado; Collado-González, Mar; Hernández Cifre, José Ginés; Díaz Baños, F. Guillermo; Víllora Cano, Gloria; Ingeniería Química
Chitosan (CS) is a biocompatible polysaccharide with positive charge that is widely used as a coating agent for negatively charged nanoparticles. However, the types of structures that emerge by combining CS and anoparticles as well as their behaviour are still poorly understood. In this work, we characterize the nanocomposites formed by gold nanoparticles (AuNPs) and CS and study the influence of CS in the expected aggregation process that should experience those nanoparticles under the favourable conditions of low pH and high ionic strength. Thus, at the working CS concentration, we observe the existence of CS structures that quickly trap the AuNPs and avoid the formation of nanoparticle aggregates in environmental conditions that, otherwise, would lead to such an aggregation.
Open Access
Density and refractive index data of binary and ternary mixtures of imidazolium-based ionic liquids, n-hexane and organic compounds involved in the kinetic resolution of rac-2-pentanol
(Elsevier, 2018-05-05) García Montalbán, Mercedes; Collado-González, Mar; Lozano-Pérez, A. Abel; Díaz Baños, F. Guillermo; Víllora Cano, Gloria; Ingeniería Química
This data article is related to the subject of the research article “Extraction of Organic Compounds Involved in the Kinetic Resolution of rac-2-Pentanol from n-hexane by Imidazolium-based Ionic Liquids:Liquid-LiquidEquilibrium” (Montalbán etal.,2018) [1]. It contains experimental data of density and refractive index of binary and ternary mixtures of imidazolium-based ionic liquids, n-hexane and organic compounds involved in the kinetic resolution of rac-2-pentanol (rac-2-pentanol, vinylbutyrate, rac-2-pentyl butyrate or butyric acid) measured at 303.15 K and 1 atm. These data are presented as calibration curves which help to determine the composition of the ionic liquid-rich phase knowing its density or refractive index.
Open Access
Liquid-liquid equilibra for ternary mixtures of 1-alkyl-3-methyl imidazolium bis{(trifluoromethyl)sulfonyl}imides, n-hexane and organic compounds at 303.15 K and 0.1 MPa
( Elsevier , 2016-08-30) García Montalbán, Mercedes; Trigo, Rocío; Collado-González, Mar; Díaz Baños, F. Guillermo; Víllora Cano, Gloria; Ingeniería Química
Ternary liquid–liquid equilibria were experimentally determined for eight systems composed of an ionic liquid + n-hexane + an organic compound implicated in the racemic resolution of rac-2-pentanol (rac-2-pentanol, vinyl butyrate, rac-2-pentyl butyrate or butyric acid) at a temperature of 303.15 K and pressure of 0.1MPa. The following ionic liquids were used: 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [emim+][NTf2-], and 1-hexyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [hmim+][NTf2-]. The binodal curves and the tie line of the conjugate phases compositions were determined through measurement of the refractive index for the ionic liquid-rich phase and by using gas chromatography for the hexane-rich phase, enabling their potential to be assessed for selective extraction of organic compounds from a mixture of ionic liquid reaction media for the resolution of rac-2-pentanol. Liquid phase activity coefficients were calculated using the Non-Random Two-Liquid equation and the tie line theoretical data calculated from the model are in good agreement with the experimental data. As yet, the literature contains no data for the systems studied in this paper.
Open Access
Terminal carbohydrates abundance, immune related enzymes, bactericidal activity and physico-chemical parameters of the Senegalese sole (Solea senegalensis, Kaup) skin mucus
(Elsevier , 2016-11-09) Collado-González, Mar; Guardiola Abellán, Francisco Antonio; Cuartero, María; Díaz Baños, F. Guillermo; Cuesta Peñafiel, Alberto; Moriñigo, Miguel Angel; Esteban Abad, María de los Ángeles; Biología Celular e Histología
Recently, interest in mucosal surfaces, more specifically fish skin and its secreted mucus, has greatly increased among immunologists. The abundance of terminal carbohydrates, several enzymes (proteases, lysozyme, peroxidase, alkaline phosphatase, esterases and ceruloplasmin), bactericidal activity against fish pathogenic and non-pathogenic bacteria and several physico-chemical parameters (protein concentration, pH, conductivity, redox potential, osmolarity, density and viscosity) in the skin mucus of Senegalese sole (Solea senegalensis, Kaup) have been evaluated. Present results evidence the abundance of N-acetylneuraminic acid, mannose, glucose and N-acetyl-galactosamine in skin mucus. The levels of lysozyme, proteases, esterases and alkaline phosphatase were very similar (from 20 to 30 Units mg−1 protein). However, 93 Units mg−1 protein were detected of ceruloplasmin and only 4′88 Units mg−1 protein of peroxidase. Skin mucus of S. senegalensis showed high bactericidal activity against the tested pathogen bacteria but weak activity against non-pathogenic bacteria. Finally, a clear relationship between mucus density and temperature was detected, while viscosity showed a direct shear- and temperature-dependent behaviour. These results could be useful for better understanding the role of the skin mucus as a key component of the innate immune system, as well as, for elucidating possible relationships between biological and physico-chemical parameters and disease susceptibility.