Nanocarrier systems are currently being developed for peptide, protein and gene delivery to protect them in the blood circulation and in the gastrointestinal tract. Polylactic acid (PLA) and poly(lactic-co-glycolic) acid (PLGA) nanoparticles loaded with a new antimicrobial GIBIM-P5S9K peptide were obtained by the double emulsion solvent extraction/evaporation method. PLA- and PLGA-NPs were spherical with sizes between 300 and 400 nm for PLA and 200 and 300 nm for PLGA and <0.3 polydispersity index as determined by dynamic light scattering and scanning electron microscopy), having the zeta potential of >20 mV. The peptide-loading efficiency of PLA-NP and PLGA-NPs was 75% and 55%, respectively. PLA- and PLGA-NPs released around 50% of this peptide over 8 h. In 10% human sera the size of peptide loaded PLA- and PLGA-NPs increased between 25.2% and 39.3%, the PDI changed from 3.2 to 5.1 and the surface charge from -7.15 to 14.6 mV. Both peptide loaded PLA- and PLGA-NPs at 0.5 μM peptide concentration inhibited the growth of Escherichia coli O157:H7 (E. coli O157:H7), methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas. aeruginosa (P. aeruginosa). In contrast, free peptide inhibited at 10 μM but did not inhibit at 0.5 and 1 μM. These PLA- and PLGA-NPs presented <10% hemolysis indicating that they are hemocompatible and promising for delivery and protection system of GIBIM-P5S9K peptide.

The effect of the composition of the nonpolar organic media on the properties of sodium 1,4-bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles (RMs) at a fixed temperature were investigated. To monitor interfacial micropolarity and sequestrated water structure in n-heptane:benzene/AOT/ water RMs, the solvatochromic behavior of coumarin 343 (C343) as an absorption and emission probe was studied, and the size of the droplets was measured by dynamic light scattering (DLS). The DLS results confirm the formation of the nheptane:benzene/AOT/water RMs at every n-heptane mole fraction investigated. The data show that as the n-heptane content increases, the interdroplet attractive interactions and the droplet size both increase. With C343 spectroscopy, we determined the "operational" critical micellar concentration, the interfacial micropolarity of the RMs, the hydrogen-bond ability of the media, and the sequestrated water structure in every RM system studied. To verify the modulation of the interdroplet interactions by the external solvent, we have used a well-known synthetic method to create gold nanopar-

An internal combustion engine operating on natural gas (NG) spiked with siloxanes has been studied experimentally with the goal of understanding the impact of siloxane impurities on engine performance. These impurities are shown to completely decompose during NG combustion in the engine to form silica microparticulates. These coat the internal metal surfaces in the engine (e.g., the piston heads) as well as the engine’s oxygen sensors and spark-plugs, and they also collect in the engine oil. A certain fraction of them, furthermore, are carried out of the engine in the flue-gas, and they deposit inside a catalyst monolith bed placed downstream of the engine resulting in its severe deactivation. These engine studies are consistent with prior fundamental studies by this team that indicate that siloxane impurities readily decompose in the NG combustion environment to form silica particulates that coat exposed metal surfaces. They also point out the critical importance for engine performance of adequately removing these siloxane impurities from NG prior to its use.

Among all novel challenges nowadays worldwide, infectious disease is probably one of the most important. It is wellknown that common treatments used include high doses of antibiotics, which are very invasive therapies for patients. These treatments are more intensive when the infection is related to multidrug resistant microorganisms. In this sense, in this work we report the use of reverse micelles to form less than 5 nm gold, silver, and gold−silver nanoparticles (NPs) with biological activity against five opportunistic Candida strains responsible of several diseases in human beings. As a result, we evaluate the interface properties and droplet−droplet interactions of micelles founding high fluidity in the polar head of the surfactant, necessary to form a flexible interaction channel in the "dimmer" micelle−micelle. In this condition, we form monodispersed, highly reactive NPs with sizes less than 5 nm with high antifungal activity against C. parapsilosis, C. Krusei, C. glabrata, C. guillermondii, and C. albicans, with minimum inhibitory concentrations (MIC 50 ) less than 0.7 ppm in all cases, the lowest reported to the best of our knowledge. These are very promising results to develop alternative therapies to treat fungal diseases in humans, animals, and plants, or to coat conventional surfaces in surgery rooms.

C343, a common molecular probe utilized in solvation dynamics experiments, was studied in homogeneous media. Absorption, emission, and (1)HNMR spectroscopies were used to investigate the behavior of C343 in benzene and in benzene/n-heptane mixtures. We demonstrate the implications of the medium polarity, measured as the Kamlet-Taft polarity-polarizability (pi*) parameter, in the C343 inter/intramolecular hydrogen bond (H-bond) interactions and the role that this interaction plays in the dimerization process of the dye. In pure benzene, the dimer prevails because the intermolecular H-bond interaction is favored. On the other hand, as the n-heptane content increases the intramolecular H-bond is the strongest and the C343 monomer is favored. As the polarity of the medium decreases, the solvophobic interaction makes that C343 monomer species experiences a more complicated aggregation process beyond the simple monomer dimer equilibrium present in pure benzene. Thus, the addition of n-heptane to the mixture yields a C343 higher-order aggregates species. Thus, our work reveals the importance that the medium has on the behavior of a widespread dye used as chromophore for very different systems such as homogeneous and microheterogenous media. This is very important since the use of chromophores without understanding its chemistry can induce artifacts into the interpretation of solvation dynamics in heterogeneous environments, in particular, those provided by biological systems such as proteins. Considerable care in choosing and characterizing the system is required to analyze the results fully.