Person: Víllora Cano, Gloria
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Complex polysaccharide-based nanocomposites for 2 oral insulin delivery
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.
Assessing chemical toxicity of ionic liquids on Vibrio fischeri: Correlation with structure and composition
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.
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
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.
Aggregation behaviour of gold nanoparticles in presence of chitosan
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.
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
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.
Chitosan as stabilizing agent for negatively charged nanoparticles
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.