The incorporation behaviors of some N-dodecanoyl amino acid-type surfactants into L-adipalmitoylphosphatidylcholine (DPPC) vesicles in aqueous solution were investigated. From the leakage measurements of a vesicle-entrapped fluorescence probe, it was found that these surfactants did not affect the DPPC vesicle so much at a very low concentration less than a one-tenth of the critical micelle concentration (CMC), but caused a significant release of the probe form the vesicles even at just below the CMC. The leakage induced by amino acid-type surfactants was promoted by increasing hydrophobicity of the amino acid. However the polarization of DPH embedded in the DPPC membrane was almost unchanged by incorporation of the surfactants at the concentration below the CMC except for the Ndodecanoylphenylalanine system. The binding enthalpy and the binding constant of the surfactant to DPPC vesicles were estimated by isothermal titration calorimetry. While the binding enthalpy was independent of the kind of surfactant, the binding constant increases with increasing hydrophobicity of the amino acid species in the surfactants. The molar ratio of bound surfactant to DPPC molecule in the saturated state was much greater than that for sodium dodecyl sulfate system. Further the ratio was not influenced by the structure of the amino acid side chain.
In order to well understand process of balloon rupture by high intensity focused ultrasound (HIFU), the process was analyzed using high speed camera. The balloon, which is used in fetal endoscopic tracheal occlusion (FETO) for treatment of congenital diaphragmatic hernia (CD H), was used. A silicon tube whose inside can be seen is a model of the trachea. The balloon was placed in the silicon tube and inflated with nanodroplet that is gasified by strong ultrasound. The balloon was irradiated with HIFU on the same conditions as our animal experiment. The balloon was ruptured at the point where was different from the focus of HIFU. The volume of the balloon was increased by HIFU irradiation. We consider that the balloon rupture is strongly related with followings, 1) increase of internal pressure of the balloon which was caused by the gasification of the nanodroplets, 2) pressing of HIFU at the upper surface of the balloon, 3) stopping HIFU energy at incident point of HIFU beam by the bubbles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.