Can aldehydes participate in the nanostructuration of liquids containing charged micelles?

Partitioning behavior of petrodiesel/biodiesel blends in water

The partitioning behavior of six petrodiesel/soybean-biodiesel blends (B0, B20, B40, B60, B80, and B100, where B100 is 100% unblended biodiesel) in water was investigated at various oil loads by the 10-fold dilution method. Five fatty acid methyl esters (FAMEs), C10-C20 n-alkanes, and four monoaromatic compounds were targeted for analysis. Only the aromatic compounds were partitioned according to Raoult's law at all oil loads. The partitioning of the FAMEs and n-alkanes at higher oil loads was found to be orders of magnitude higher than the reported aqueous solubilities of these compounds, and directly correlated with the amount of oil load applied. Depth filtration of the water-accommodated fractions (WAFs) significantly reduced the observed concentrations of the FAMEs and n-alkanes, but did not appreciably affect the aromatic compounds. The FAMEs and n-alkanes concentrations in the filtered WAFs agreed with the aqueous solubilities of those compounds reported in the literature, but the n-alkanes showed progressive deviations from those solubilities with the increase in the amount of biodiesel in the blends. Further dilution experiments on pure n-hexadecane confirmed the presence of a metastable colloidal phase that seems to be controlled by hydrophobic interactions and surface phenomena. The addition of biodiesel to the oil blend appeared to have a positive impact on the dissolved concentrations and the colloidal accommodation of the n-alkanes. Autoxidation of the biodiesel constituents was found to be significant, and increased with increasing oil loads. Chemical products such as hexanal, n-butyl acetate, diethylene glycol monobutyl ether, and diethylene glycol monobutyl ether acetate were positively identified among the FAMEs' autoxidation byproducts. Our data suggest a positive enhancement for biodiesel on the formation of the oil in water colloidal phase, possibly by forming a surfactant-cosurfactant-like pair of the FAMEs and their autoxidation byproducts.

Stability and aerosolization of pressurized metered dose inhalers containing thymopentin nanoparticles produced using a bottom-up process

The objective of this study was to investigate the stability and aerosolization of pressurized metered dose inhalers (pMDIs) containing thymopentin nanoparticles. Thymopentin nanoparticles, fabricated by a bottom-up process, were suspended in hydrofluoroalkane (HFA) 134a together with cineole and/or n-heptane to produce pMDI formulations. The stability study of the pMDIs obtained was carried out at ambient temperature for 6 months. The amount of thymopentin and the aerosolization properties of pMDIs were determined using high-performance liquid chromatography (HPLC) and a twin-stage impinger (TSI), respectively. Based on the results, thymopentin nanoparticles were readily suspended in HFA 134a with the aid of cineole and/or n-heptane to form physically stable pMDI formulations, and more than 98% of the labeled amount of thymopentin and over 50% of the fine particle fraction (FPF) of the pMDIs were achieved. During storage, it was found that for all pMDIs more than 97% of the labeled amount of thymopentin and FPF greater than 47% were achieved. Moreover, the size of thymopentin nanoparticles in propellant containing cineole and n-heptane showed little change. It is, therefore, concluded that the pMDIs comprising thymopentin nanoparticles developed in this study were stable and suitable for inhalation therapy for systemic action.

Insulin nanoparticles: stability and aerosolization from pressurized metered dose inhalers

Nanoparticles containing insulin have been produced by emulsification processes followed by freeze-drying. Purified nanoparticles were suspended in hydrofluoroalkane (HFA) 134a, using essential oils (cineole and citral) as suspension stabilizers to form pressurized metered dose inhaler (pMDI) formulations. The retention of insulin integrity after formulation processing was determined using high performance liquid chromatography (HPLC), size exclusion chromatography (SEC), circular dichroism (CD) and fluorescence spectroscopy. The results indicated that the native structure of insulin was retained after formulation processing. Aerosolization properties of the manufactured pMDI formulations were determined using a multi-stage liquid impinger. The results showed that the nanoparticles were suitable for peripheral lung deposition, with a fine particle fraction (FPF(<1.7 microm)) of approximately 45% (w/w). In conclusion, the pMDI formulations with nanoparticles containing insulin developed in this study have the potential to deliver protein therapeutics via inhalation for systemic action.

Physicochemical investigations of microemulsification of eucalyptus oil and water using mixed surfactants (AOT+Brij-35) and butanol

Microemulsification of a vegetable oil (eucalyptus) with single and mixed surfactants (AOT and Brij-35), cosurfactant of different lipophilicities (isomers of butanol), and water were studied at different surfactant and cosurfactant mixing ratios. The phase diagrams of the quaternary systems were constructed using unfolded and folded tetrahedron, wherein the phase characteristics of different ternary systems can be underlined. The microemulsion zone was found to be dependent upon the mixing ratios of surfactant and cosurfactant; the largest microemulsion zone was formed with 1:1 (w/w) S:CS. The effects of temperature and additives (NaCl, urea, glucose, and bile salts of different concentrations) on the phase behavior were examined. The mixed microemulsion system showed temperature insensitivity, whereas the Brij-35 (single) stabilized system exhibited a smaller microemulsion zone at elevated temperature. NaCl and glucose increased the microemulsion zone up to a certain concentration, beyond which the microemulsion zones were decreased. These additives decreased the microemulsion zones as temperature was increased. The effect of urea on microemulsion zone was found to be insignificant even at the concentration 3.0 mol dm(-3). Little effect on microemulsion zone was shown by NaC (sodium cholate) at 0.25 and 0.5 mol dm(-3) at different temperatures. The conductance of the single (AOT) and mixed microemulsion system (AOT+Brij-35) depends upon the water content and mixing ratios of the surfactants, and a steep rise in conductance was observed at equal weight percentages of oil and water. Viscosities for both single (AOT) and mixed (AOT+Brij-35) surfactant systems passed through maxima at equal oil and water regions showing structural transition. The viscosities for microemulsion systems increased with increasing Brij-35 content in the AOT+Brij-35 blend. Conductances and viscosities of different monophasic compositions in the absence and presence of additives (NaCl and NaC) were measured at different temperatures. The activation energy of conduction (DeltaE(cond)( *)) and the activation enthalpy for viscous flow (DeltaH(vis)( *)) were evaluated. It was found that both DeltaE(cond)( *) and DeltaH(vis)( *) were a function of the nature of the dispersion medium. Considering the phase separation point of maximum solubility, the free energy of dissolution of water or oil (DeltaG(s)(0)) at the microdispersed state in amphiphile medium was estimated and found to be a function of surfactant composition.

Biooxidation of n-hexanol by alcohol oxidase and catalase in biphasic and micellar systems without solvent

Alcohol oxidase from Pichia pastoris together with catalase from bovine liver was used to oxidize n-hexanol to hexanal. For this purpose, an aqueous buffer solution was mixed with large amounts of hexanol by simple agitation, yielding a biphasic system, or by adding the nonionic surfactant Brij 35. Initial velocities and reaction yields after 24 h were measured as a function of various parameters such as the amounts of enzymes, hexanol, or surfactant. High enzymatic activity was determined for hexanol concentrations of between 20 mass% and 80 mass% without using any additional organic solvent. The homogenization of the biphasic systems with the help of Brij 35 did not yield a significant improvement of the bioconversion, which would justify the use of surfactants.