The α,α-(1→1) linkage of trehalose is key to anhydrobiotic preservation

This study compares the efficacy of six disaccharides and glucose for the preservation of solid supported lipid bilayers (SLBs) upon exposure to air. Disaccharide molecules containing an α,α-(1→1) linkage, such as α,α-trehalose and α,α-galacto-trehalose, were found to be effective at retaining bilayer structure in the absence of water. These sugars are known to crystallize in a clam shell conformation. Other saccharides, which are found to crystallize in more open structures, did not preserve the SLB structure during the drying process. These included the nonreducing sugar, sucrose, as well as maltose, lactose, and the monosaccharide, glucose. In fact, even close analogs to α,α-trehalose, such as α,β- trehalose, which connects its glucopyranose rings via a (1→1) linkage in an axial, equatorial fashion, permitted nearly complete delamination and destruction of supported bilayers upon exposure to air. Lipids with covalently attached sugar molecules such as ganglioside GM₁, lactosyl phosphatidylethanolamine, and glucosylcerebroside were also ineffective at preserving bilayer structure. The liquid crystalline-to-gel phase transition temperature of supported phospholipid bilayers was tested in the presence of sugars in a final set of experiments. Only α,α-trehalose and α,α-galacto-trehalose depressed the phase transition temperature, whereas the introduction of other sugar molecules into the bulk solution caused the phase transition temperature of the bilayer to increase. These results point to the importance of the axial-axial linkage of disaccharides for preserving SLB structure.