We have investigated the morphology of dimyristoyl phosphatidyl choline (DMPC)—cholesterol mixed monolayer formed on the water surface by dropping method using surface tension measurement (STm), Brewster angle micros...We have investigated the morphology of dimyristoyl phosphatidyl choline (DMPC)—cholesterol mixed monolayer formed on the water surface by dropping method using surface tension measurement (STm), Brewster angle microscopy (BAM), and infrared external reflection spectroscopy (IERS). STm results showed negative deviation of the limiting molecular area (A0) of cholesterol occurred when cholesterol was added to the DMPC monolayer. BAM images showed the expandable DMPC monolayer changed to the condensed rigid monolayer at more than cholesterol mole fraction (xChol) 0.4. IERS recordings showed that the addition of cholesterol at xChol = 0.4 occurred structural change from gauche- to trans- conformation of two DMPC molecule alkyl chains. From these results, it is found that cholesterol molecule has specific properties that cause structural transition of DMPC molecule alkyl chains.展开更多
The gel-liquid crystal phase transitions of the pseudo-binary systems of cephalins DMPE and DHPE in excess water were studied by differential scanning calorimetry. The phase diagram of the pseudebinary systems has bee...The gel-liquid crystal phase transitions of the pseudo-binary systems of cephalins DMPE and DHPE in excess water were studied by differential scanning calorimetry. The phase diagram of the pseudebinary systems has been given. The experiments showed that the partial phase separation in gel phase might occur at least at the mole fractions of DHPE below 0.1. The analysis by the model of ideal solution showed that both the cephalins were non-ideally miscible both in the gel phases and in the liquid crystal phases. The analysis by the model of regular solution showed that all the non-ideality parameters in the gel phases were larger than those in the liquid crystal phases at the same temperature. All the non-ideality parameters were not constant, but rather dependent on temperature.展开更多
文摘We have investigated the morphology of dimyristoyl phosphatidyl choline (DMPC)—cholesterol mixed monolayer formed on the water surface by dropping method using surface tension measurement (STm), Brewster angle microscopy (BAM), and infrared external reflection spectroscopy (IERS). STm results showed negative deviation of the limiting molecular area (A0) of cholesterol occurred when cholesterol was added to the DMPC monolayer. BAM images showed the expandable DMPC monolayer changed to the condensed rigid monolayer at more than cholesterol mole fraction (xChol) 0.4. IERS recordings showed that the addition of cholesterol at xChol = 0.4 occurred structural change from gauche- to trans- conformation of two DMPC molecule alkyl chains. From these results, it is found that cholesterol molecule has specific properties that cause structural transition of DMPC molecule alkyl chains.
基金Project supported by the National Natural Science Foundation of China (Grant No. 29573097)
文摘The gel-liquid crystal phase transitions of the pseudo-binary systems of cephalins DMPE and DHPE in excess water were studied by differential scanning calorimetry. The phase diagram of the pseudebinary systems has been given. The experiments showed that the partial phase separation in gel phase might occur at least at the mole fractions of DHPE below 0.1. The analysis by the model of ideal solution showed that both the cephalins were non-ideally miscible both in the gel phases and in the liquid crystal phases. The analysis by the model of regular solution showed that all the non-ideality parameters in the gel phases were larger than those in the liquid crystal phases at the same temperature. All the non-ideality parameters were not constant, but rather dependent on temperature.
