Time-dependent mixing and demixing processes in binary lipid monolayers studied by mixed and separate spreading using film pressure and film potential measurements

Influence of a Spreading Method on the Properties of Amphotericin B−Dipalmitoyl Phosphatidic Acid Mixed Films at the Air/Water Interface

“…Because the highest deviation from the additivity rule is observed for the mixtures of X AmB between 0.5 and 0.7 (Figure ), one may assume that the highest stability of the complex is reached at X AmB = 0.66, corresponding to a system of 2:1 AmB/DPPA (i.e., the one in which a phospholipid molecule is sandwiched between two AmB molecules). The complexes of the same stoichiometry have been reported for similar systems. ,, Likewise, the slow, spontaneous mixing of separately spread monolayer components has been observed by several authors. − …”

Interaction between Amphotericin B and Sterols in Monolayers. Mixed Films of Ergosterol−Amphotericin B

“…However, the finding that when ergosterol and AmB are spread separately on the substrate there is a gradual rise in the surface pressure of the low-pressure π− A inflection region as the two components diffuse into each other (Figure ) suggests that in all cases this region reflects the transition of AmB molecules from horizontal to vertical orientation, and that the rise in surface pressure is due to an increasing, presumably nonhydrophobic, attractive interaction between AmB and ergosterol molecules (minimal when the monolayer components are spread separately and left only for a short time (10 min) before film compression (Figure , curve 2), greater when the components are spread separately but left for a longer time (2 h) allowing mutual diffusion (Figure , curve 3), and greatest when the component mixture is prepared before the film is spread (Figure , curve 1)). The slow, spontaneous mixing of initially unmixed monolayer components has been observed by several authors. − Attractive interaction between AmB and ergosterol molecules would also account for the transition region of curve 1 in Figure occurring at smaller mean molecular areas than the low-pressure transition region of curve 2. It is hoped that further research using other techniques such as BAM or fluorescence microscopy may confirm these findings.…”