TY - JOUR

T1 - Dehydrating phospholipid vesicles measured in real-time using ATR Fourier transform infrared spectroscopy

AU - Wolkers, Willem F.

AU - Oldenhof, Harriëtte

AU - Glasmacher, Birgit

N1 - Funding Information: Statement of funding: This work is supported by funding from the German Research Foundation (DFG, Deutsche Forschungsgemeinschaft) for the Cluster of Excellence “From Regenerative Biology to Reconstructive Therapy” (REBIRTH).

PY - 2010/8

Y1 - 2010/8

N2 - According to the water replacement hypothesis, trehalose stabilizes dry membranes by preventing the decrease in spacing between adjacent phopspholipid headgroups during dehydration. Alternatively, the water-entrapment hypothesis postulates that in the dried state sugars trap residual water at the biomolecule sugar interface. In this study, Fourier transform infrared spectroscopy with an attenuated total reflection accessory was used to investigate the influence of trehalose on the dehydration kinetics and residual water content of egg phosphatidylcholine liposomes in real time under controlled relative humidity conditions. In the absence of trehalose, the lipids displayed a transition to a more ordered gel phase upon drying. The membrane conformational disorder in the dried state was found to decrease with decreasing relative humidity. Even at a relative humidity as high as 94% the conformational disorder of the lipid acyl chains decreased after evaporation of the bulk water. The presence of trehalose affects the rate of water removal from the system and the lipid phase behavior. The rate of water removal is decreased and the residual water content is higher, as compared to drying in the absence of trehalose. During drying, the level of hydrogen bonding to the head groups remains constant. In addition, the conformational disorder of the lipid acyl chains in the dried state more closely resembles that of the lipids in the fully hydrated state. We conclude that water entrapment rather than water replacement explains the effect of trehalose on lipid phase behavior of phosphatidylcholine lipid bilayers during the initial phase of drying.

AB - According to the water replacement hypothesis, trehalose stabilizes dry membranes by preventing the decrease in spacing between adjacent phopspholipid headgroups during dehydration. Alternatively, the water-entrapment hypothesis postulates that in the dried state sugars trap residual water at the biomolecule sugar interface. In this study, Fourier transform infrared spectroscopy with an attenuated total reflection accessory was used to investigate the influence of trehalose on the dehydration kinetics and residual water content of egg phosphatidylcholine liposomes in real time under controlled relative humidity conditions. In the absence of trehalose, the lipids displayed a transition to a more ordered gel phase upon drying. The membrane conformational disorder in the dried state was found to decrease with decreasing relative humidity. Even at a relative humidity as high as 94% the conformational disorder of the lipid acyl chains decreased after evaporation of the bulk water. The presence of trehalose affects the rate of water removal from the system and the lipid phase behavior. The rate of water removal is decreased and the residual water content is higher, as compared to drying in the absence of trehalose. During drying, the level of hydrogen bonding to the head groups remains constant. In addition, the conformational disorder of the lipid acyl chains in the dried state more closely resembles that of the lipids in the fully hydrated state. We conclude that water entrapment rather than water replacement explains the effect of trehalose on lipid phase behavior of phosphatidylcholine lipid bilayers during the initial phase of drying.

KW - Anhydrobiosis

KW - Fourier transform infrared spectroscopy

KW - Lipid phase behavior

KW - Liposomes

KW - Lyotropism

KW - Trehalose

KW - Water replacement hypothesis

UR - http://www.scopus.com/inward/record.url?scp=77955414935&partnerID=8YFLogxK

U2 - 10.1016/j.cryobiol.2010.06.001

DO - 10.1016/j.cryobiol.2010.06.001

M3 - Article

C2 - 20566369

AN - SCOPUS:77955414935

VL - 61

SP - 108

EP - 114

JO - CRYOBIOLOGY

JF - CRYOBIOLOGY

SN - 0011-2240

IS - 1

ER -