TY - JOUR
T1 - Ultrasound interaction with large unilamellar vesicles at the phospholipid phase transition
T2 - Perturbation by phospholipid side chain substitution with deuterium
AU - Morse, Reef
AU - Ma, Loralie D.
AU - Magin, Richard L.
AU - Dunn, Floyd
PY - 1999/12
Y1 - 1999/12
N2 - The ultrasonic absorption, αλ, as a function of temperature and frequency was determined in large unilamellar vesicles (LUVs) in which specific phospholipid side chains were deuterated. Deuteration significantly altered the temperature and frequency dependence of αλ. The frequency change was especially marked, with decreased frequency and broadening of the ultrasound relaxation, even with only minor changes in the phase transition temperature. Deuteration decreased the T(m) and enthalpy of the lipid phase transition, as shown by differential scanning calorimetry, whereas electron spin resonance showed that at and above the lipid phase transition, no differences in the mobility as a function of temperature were observed. These results show that the observed increase in ultrasonic absorption in LUVs at the phospholipid phase transition arises from the interaction of ultrasound with the hydrophobic side chains, probably coupling with structural reorganization of small domains of molecules, a process which is maximized at the phase transition temperature. Copyright (C) 1999 Elsevier Science Ireland Ltd.
AB - The ultrasonic absorption, αλ, as a function of temperature and frequency was determined in large unilamellar vesicles (LUVs) in which specific phospholipid side chains were deuterated. Deuteration significantly altered the temperature and frequency dependence of αλ. The frequency change was especially marked, with decreased frequency and broadening of the ultrasound relaxation, even with only minor changes in the phase transition temperature. Deuteration decreased the T(m) and enthalpy of the lipid phase transition, as shown by differential scanning calorimetry, whereas electron spin resonance showed that at and above the lipid phase transition, no differences in the mobility as a function of temperature were observed. These results show that the observed increase in ultrasonic absorption in LUVs at the phospholipid phase transition arises from the interaction of ultrasound with the hydrophobic side chains, probably coupling with structural reorganization of small domains of molecules, a process which is maximized at the phase transition temperature. Copyright (C) 1999 Elsevier Science Ireland Ltd.
KW - Large unilamellar vesicles
KW - Phospholipid phase transition
KW - Ultrasound interaction
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U2 - 10.1016/S0009-3084(99)00068-7
DO - 10.1016/S0009-3084(99)00068-7
M3 - Article
C2 - 10701075
AN - SCOPUS:0344117506
SN - 0009-3084
VL - 103
SP - 1
EP - 10
JO - Chemistry and Physics of Lipids
JF - Chemistry and Physics of Lipids
IS - 1-2
ER -