Solubilization and thermodynamic properties of simvastatin in various micellar solutions of different non-ionic surfactants: Computational modeling and solubilization capacity

The aim of this work was to solubilize simvastatin (SIM) using different micellar solutions of various non-ionic surfactants such as Tween-80 (T80), Tween-20 (T20), Myrj-52 (M52), Myrj-59 (M59), Brij-35 (B35) and Brij-58 (B58). The solubility of SIM in water (H2O) and different micellar concentrations of T80, T20, M52, M59, B35 and B58 was determined at temperatures T = 300.2 K to 320.2 K under atmospheric pressure p = 0.1 MPa using saturation shake flask method. The experimental solubility data of SIM was regressed using van’t Hoff and Apelblat models. The solubility of SIM (mole fraction) was recorded highest in M59 (1.54 x 10−2) followed by M52 (6.56 x 10−3), B58 (5.52 x 10−3), B35 (3.97 x 10−3), T80 (1.68 x 10−3), T20 (1.16 x 10−3) [the concentration of surfactants was 20 mM in H2O in all cases] and H2O (1.94 x 10−6) at T = 320.2 K. The same results were also recorded at each temperature and each micellar concentration of T80, T20, M52, M59, B35 and B58. “Apparent thermodynamic analysis” showed endothermic and entropy-driven dissolution/solubilization of SIM in H2O and various micellar solutions of T80, T20, M52, M59, B35 and B58.

Studies of Thermo-acoustical Properties of Polyoxyethylene (20) cetyl ether (Brij-58) in Presence of Additives at Different Temperatures

The measurement of ultrasonic velocity and density as a function of temperature and concentration of additives were carried out. The variation of ultrasonic velocity and density of micellar solution of Polyoxyethylene (20) cetyl ether (Brij-58, CMC= 0.0086% w/v) in the presence of polymer PVP and PEO were studied at 298.15, 303.15, 308.15 and 313.15K. Various acoustic parameters such as adiabatic compressibility (?ad), molar volume (Vm), intermolecular free length (Lf), acoustic impedance (Z) and surface tension (?) of aqueous solution of Brij-58 and Brij-58-polymer mixed solutions were derived from these data. The results were discussed on the basis of polymer-surfactant interactions and hydrophobic interaction, which in turn depends upon the structural arrangement of the linkages involved and difference in the chain which binds the hydrophobic and hydrophilic group in the studied surfactant molecule. It was noted that the ultrasound velocity decreases with increase in temperature. The decrease in the value of ?ad and Lf with increase in ultrasonic velocity indicates that there is significant interaction between the surfactant molecule and added polymer PVP and PEO.

AupA and AupB Are Outer and Inner Membrane Proteins Involved in Alkane Uptake inMarinobacter hydrocarbonoclasticusSP17

ABSTRACTThis study describes the functional characterization of two proteins, AupA and AupB, which are required for growth on alkanes in the marine hydrocarbonoclastic bacteriumMarinobacter hydrocarbonoclasticus. TheaupAandaupBgenes form an operon whose expression was increased upon adhesion to and biofilm formation onn-hexadecane. AupA and AupB are outer and inner membrane proteins, respectively, which are able to interact physically. Mutations inaupAor/andaupBreduced growth on solid paraffin and liquidn-hexadecane, while growth on nonalkane substrates was not affected. In contrast, growth ofaupmutants onn-hexadecane solubilized in Brij 58 micelles was completely abolished. Mutant cells had also lost the ability to bind ton-hexadecane solubilized in Brij 58 micelles. These results support the involvement of AupA and AupB in the uptake of micelle-solubilized alkanes and provide the first evidence for a cellular process involved in the micellar uptake pathway. The phylogenetic distribution of theaupABoperon revealed that it is widespread in marine hydrocarbonoclastic bacteria of the ordersOceanospirillalesandAlteromonadalesand that it is present in high copy number (up to six) in someAlcanivoraxstrains. These features suggest that Aup proteins probably confer a selective advantage in alkane-contaminated seawater.IMPORTANCEBacteria are the main actors of the biological removal of hydrocarbons in seawater, and so, it is important to understand how they degrade hydrocarbons and thereby mitigate marine environmental damage. Despite a considerable amount of literature about the dynamic of microbial communities subjected to hydrocarbon exposure and the isolation of strains that degrade hydrocarbons, most of the genetic determinants and molecular mechanisms of bacterial hydrocarbon uptake remain unknown. This study identifies two genes,aupAandaupB, in the hydrocarbonoclastic bacteriumMarinobacter hydrocarbonoclasticusthat are present frequently in multiple copies in most of the marine hydrocarbon-degrading bacteria for which the genomic sequence is available. AupA and AupB are two novel membrane proteins interacting together that are involved in the uptake of alkanes dissolved in surfactant micelles. The function and the phylogenetic distribution ofaupAandaupBsuggest that they might be one attribute of the remarkable adaptation of marine hydrocarbonoclastic bacteria that allow them to take advantage of hydrocarbons.