DSC experiment were performed with a differential scanning calorimeter . All scans were carried out with a scan rate of 30/h in the temperature range between 25◦Cand75◦C. before measurement the samples were degassed and equilibrated for 15 min before heating. Two heating and cooling cycles were performed .We have examined freshly prepared liposomes,frozen liposomes immediately after thawing and freeze-dried liposomes after re-suspension in purified water .In general ,re- suspension was completed within 5 min by repeated vortexing and heating above the phase transition temperature of the main lipid component(about60◦C). However, to test whether the samples were fully hydrated after this short period, we have performed experiments with longer re-suspension times up to 45 min with 10 min inter-vals.For all DSC experiments a molar lipid to carbohydrate ratio of 1:10(about 1% (w/v) carbohydrate ) was used .Immediately before measurements ,the total lipid content was adjusted to 1 mg/ml with Tris-buffer, which was also employed as reference.
Calorimetric enthalpies (Hcal) were calculated after baseline adjustment and normalization to the phospholipid concentration, by integrating the peak areas using the MicroCal LLC Origin soft-ware ( OriginLab Corporation ,Northampton ,MA,USA).The actual transition temperatures
Were determined at the peak maxima in the heat capacity functions andT1/2Was derived from the half-width of the transition peak indicative for the cooperativity of the transition.
DSC experiment were performed with a differential scanning calorimeter . All scans were carried out with a scan rate of 30/h in the temperature range between 25◦Cand75◦C. before measurement the samples were degassed and equilibrated for 15 min before heating. Two heating and cooling cycles were performed .We have examined freshly prepared liposomes,frozen liposomes immediately after thawing and freeze-dried liposomes after re-suspension in purified water .In general ,re- suspension was completed within 5 min by repeated vortexing and heating above the phase transition temperature of the main lipid component(about60◦C). However, to test whether the samples were fully hydrated after this short period, we have performed experiments with longer re-suspension times up to 45 min with 10 min inter-vals.For all DSC experiments a molar lipid to carbohydrate ratio of 1:10(about 1% (w/v) carbohydrate ) was used .Immediately before measurements ,the total lipid content was adjusted to 1 mg/ml with Tris-buffer, which was also employed as reference.Calorimetric enthalpies (Hcal) were calculated after baseline adjustment and normalization to the phospholipid concentration, by integrating the peak areas using the MicroCal LLC Origin soft-ware ( OriginLab Corporation ,Northampton ,MA,USA).The actual transition temperatures Were determined at the peak maxima in the heat capacity functions andT1/2Was derived from the half-width of the transition peak indicative for the cooperativity of the transition.
正在翻譯中..