TY - JOUR
T1 - Thermodynamic behavior and relaxation processes of mixed DPPC/cholesterol monolayers at the air/water interface
AU - Chou, Tzung Han
AU - Chang, Chien Hsiang
N1 - Funding Information:
This research was supported by the National Science Council of the Republic of China through grant no. NSC 87-2214-E006-016.
Copyright:
Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.
PY - 2000/2/15
Y1 - 2000/2/15
N2 - This study investigated the thermodynamic behavior and relaxation processes of mixed DPPC/cholesterol monolayers at the air/water interface at 37°C. Surface pressure-area isotherms and relaxation curves for the mixed monolayers were obtained by using a computer-controlled film balance. In the thermodynamic analysis of the mixed monolayers, the areas of monolayers exhibited negative deviations from the ideal values at all compositions for lower surface pressures. However, at higher surface pressures, distinctively positive deviations from ideality were observed at lower DPPC contents. Excess free energies of mixing had been calculated and the most stable state of the mixed monolayer with x(DPPC) = 0.5 or 0.6 was found. Moreover, the relaxation kinetics of the mixed monolayers was investigated by measuring the surface area as a function of time at a constant surface pressure of 40 mN m-1. It was shown that the relaxation processes could be described by the models considering nucleation and growth mechanisms.
AB - This study investigated the thermodynamic behavior and relaxation processes of mixed DPPC/cholesterol monolayers at the air/water interface at 37°C. Surface pressure-area isotherms and relaxation curves for the mixed monolayers were obtained by using a computer-controlled film balance. In the thermodynamic analysis of the mixed monolayers, the areas of monolayers exhibited negative deviations from the ideal values at all compositions for lower surface pressures. However, at higher surface pressures, distinctively positive deviations from ideality were observed at lower DPPC contents. Excess free energies of mixing had been calculated and the most stable state of the mixed monolayer with x(DPPC) = 0.5 or 0.6 was found. Moreover, the relaxation kinetics of the mixed monolayers was investigated by measuring the surface area as a function of time at a constant surface pressure of 40 mN m-1. It was shown that the relaxation processes could be described by the models considering nucleation and growth mechanisms.
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U2 - 10.1016/S0927-7765(99)00102-2
DO - 10.1016/S0927-7765(99)00102-2
M3 - Article
AN - SCOPUS:0033991253
VL - 17
SP - 71
EP - 79
JO - Colloids and Surfaces B: Biointerfaces
JF - Colloids and Surfaces B: Biointerfaces
SN - 0927-7765
IS - 2
ER -