Hydrophilic Carotenoids: Surface Properties and Aggregation of Crocin as a Biosurfactant

The surface and aggregation properties of the naturally occurring carotenoid crocin ( 1 ), examined through measurements of surface tension and UV/VIS absorption, have been used to determine the following parameters: critical aggregate concentration, surface‐saturation concentration, molecular area, free energy of adsorption and micellation, adsorption‐micellar energy relationship, equilibrium constants, and aggregate size. On structural grounds and based on the determined molecular area at the interface, the digentiobiosyl ester of the conjugated, highly unsaturated carotenoid diacid crocetin C20 : 7 should be classified as a bolaamphiphile. Crocin forms true monomolecular solutions in H₂O; only at rather high concentrations aggregation occurs.     

青霉素G钾盐对SDS水溶液物理化学性质的影响及其在SDS/n-C5H11OH/H2O体系中的释放

The effects of penicillin potassium salt （PenK） on the solubility, Krafft temperature TK, critical micelle concentration CMC of SDS micelle and the phase behavior of SDS/n-C5H11OH/H2O system were studied. The partial phase diagrams of SDS/PenK/H2O system at different temperatures were determined. The release amounts of PenK in SDS/n-C5H11OH/H2O system and the distribution coefficient of PenK between micelle and water were measured by UV-Vis spectroscopy. The results show that in the presence of PenK, the CMC of SDS was decreased while the TK of SDS was increased and the solubility of SDS in both water and SDS/n-C5H11OH/H2O oil in water （O/W） microemulsion was decreased, but increased in water in oil （W/O） microemulsion. SDS micelles and SDS/n- C5H11OH/H20 O/W microemulsion could accelerate the release rate of PenK. The addition of SDS and water could both increase the release rate of PenK, whereas the presence of n-C5H11OH reduced the release rate of PenK. The above results were related to the electrostatic repulsion between PenK and SDS.