Highlights First report of the determination of doxofylline and its metabolites in plasma. Go... more Highlights First report of the determination of doxofylline and its metabolites in plasma. Good accuracy, precision and recovery was achieved by protein precipitation. The method was successfully applied to a pharmacokinetic study in human.
Microorganisms synthesise a wide range of surface-active compounds (SAC), generally called biosur... more Microorganisms synthesise a wide range of surface-active compounds (SAC), generally called biosurfactants. These compounds are mainly classified according to their molecular weight, physico-chemical properties and mode of action. The low-molecular-weight SACs or biosurfactants reduce the surface tension at the air/water interfaces and the interfacial tension at oil/water interfaces, whereas the high-molecular-weight SACs, also called bioemulsifiers, are more effective in stabilising oil-in-water emulsions. Biosurfactants are attracting much interest due to their potential advantages over their synthetic counterparts in many fields spanning environmental, food, biomedical, and other industrial applications. Their large-scale application and production, however, are currently limited by the high cost of production and by limited understanding of their interactions with cells and with the abiotic environment. In this paper, we review the current knowledge and the latest advances in biosurfactant applications and the biotechnological strategies being developed for improving production processes and future potential.
The use of small angle neutron scattering, SANS, neutron reflectivity, NR, and surface tension to... more The use of small angle neutron scattering, SANS, neutron reflectivity, NR, and surface tension to study the mixing properties of the biosurfactant rhamnolipid with a conventional anionic surfactant, sodium dodecyl 6-benzene sulfonate, LAS, is reported. The monorhamnose rhamnolipid, R1, mixes close to ideally with LAS at the air-water interface, whereas for mixtures of LAS with the dirhamnose rhamnolipid, R2, the LAS strongly partitions to the air-water interface relative to R2, probably because of the steric hindrance of the larger R2 headgroup. These trends in the binary mixtures are also reflected in the ternary R1/R2/LAS mixtures. However, for these ternary mixtures, there is also a pronounced synergy in the total adsorption, which reaches a maximum for a LAS/rhamnolipid mole ratio of about 0.6 and a R1/R2 mol ratio of about 0.5, an effect which is not observed in the binary mixtures. In solution, the R1/LAS mixtures form relatively small globular micelles, L 1 , at low surfactant concentrations (<20 mM), more planar structures (lamellar, L R , unilamellar/multilamellar vesicles, ulv/mlv) are formed at higher surfactant concentrations for R1 and LAS rich compositions, and a large mixed phase (L R /L 1 and L 1 /L R) region forms at intermediate surfactant compositions. In contrast, for the R2/LAS mixtures, the higher preferred curvature of R2 dominates the phase behavior. The predominant microstructure is in the form of small globular micelles, except for solution compositions rich in LAS (>80 mol % LAS) where more planar structures are formed. For the ternary mixtures, there is an evolution in the resulting phase behavior from one dominated by L 1 (R2 rich) to one dominated by planar structures, L R , (R1, LAS rich), and which strongly depends upon the LAS/rhamnolipid and R1/R2 mole ratio.
Highlights First report of the determination of doxofylline and its metabolites in plasma. Go... more Highlights First report of the determination of doxofylline and its metabolites in plasma. Good accuracy, precision and recovery was achieved by protein precipitation. The method was successfully applied to a pharmacokinetic study in human.
Microorganisms synthesise a wide range of surface-active compounds (SAC), generally called biosur... more Microorganisms synthesise a wide range of surface-active compounds (SAC), generally called biosurfactants. These compounds are mainly classified according to their molecular weight, physico-chemical properties and mode of action. The low-molecular-weight SACs or biosurfactants reduce the surface tension at the air/water interfaces and the interfacial tension at oil/water interfaces, whereas the high-molecular-weight SACs, also called bioemulsifiers, are more effective in stabilising oil-in-water emulsions. Biosurfactants are attracting much interest due to their potential advantages over their synthetic counterparts in many fields spanning environmental, food, biomedical, and other industrial applications. Their large-scale application and production, however, are currently limited by the high cost of production and by limited understanding of their interactions with cells and with the abiotic environment. In this paper, we review the current knowledge and the latest advances in biosurfactant applications and the biotechnological strategies being developed for improving production processes and future potential.
The use of small angle neutron scattering, SANS, neutron reflectivity, NR, and surface tension to... more The use of small angle neutron scattering, SANS, neutron reflectivity, NR, and surface tension to study the mixing properties of the biosurfactant rhamnolipid with a conventional anionic surfactant, sodium dodecyl 6-benzene sulfonate, LAS, is reported. The monorhamnose rhamnolipid, R1, mixes close to ideally with LAS at the air-water interface, whereas for mixtures of LAS with the dirhamnose rhamnolipid, R2, the LAS strongly partitions to the air-water interface relative to R2, probably because of the steric hindrance of the larger R2 headgroup. These trends in the binary mixtures are also reflected in the ternary R1/R2/LAS mixtures. However, for these ternary mixtures, there is also a pronounced synergy in the total adsorption, which reaches a maximum for a LAS/rhamnolipid mole ratio of about 0.6 and a R1/R2 mol ratio of about 0.5, an effect which is not observed in the binary mixtures. In solution, the R1/LAS mixtures form relatively small globular micelles, L 1 , at low surfactant concentrations (<20 mM), more planar structures (lamellar, L R , unilamellar/multilamellar vesicles, ulv/mlv) are formed at higher surfactant concentrations for R1 and LAS rich compositions, and a large mixed phase (L R /L 1 and L 1 /L R) region forms at intermediate surfactant compositions. In contrast, for the R2/LAS mixtures, the higher preferred curvature of R2 dominates the phase behavior. The predominant microstructure is in the form of small globular micelles, except for solution compositions rich in LAS (>80 mol % LAS) where more planar structures are formed. For the ternary mixtures, there is an evolution in the resulting phase behavior from one dominated by L 1 (R2 rich) to one dominated by planar structures, L R , (R1, LAS rich), and which strongly depends upon the LAS/rhamnolipid and R1/R2 mole ratio.
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Papers by Thomas Smyth