Using Fluorescence and Infrared Spectroscopy to Analyze the Interaction of Disaccharides with Lipid Bilayers

Abstract

It is well known that sugars, such as trehalose, dehydrate lipid membranes based upon the Water Replacement Hypothesis. Here, we have investigated the interaction between different sugars (sucralose, sucrose, and trehalose) and model phospholipid membrane 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) using fluorescence spectroscopy with the fluorescent probe Laurdan and infrared spectroscopy. For the fluorescence measurements, the addition of sugar molecules to the bilayer resulted in a decrease in the Generalized Polarization (GP) values, corresponding to an increase in polarity in the environment within the bilayer around the probe. A decrease in GP values of Laurdan also suggest the possibility of coexisting phases within the bilayer. Infrared spectroscopy was used to investigate the dynamics of the hydrophilic and hydrophobic regions of the membrane as the changes of the asymmetric phosphate group and fatty acid chain vibrational bands were monitored when introduced to sucrose and sucralose. These tests revealed that sucrose had no significant impact on the membrane in either region of the bilayer, while sucralose showed a significant impact on both regions of the bilayer. Overall, we have monitored the interaction of different sugar molecules with model DPPC membranes through fluorescence and infrared spectroscopy measurements to explore the polarity of the bilayer and the possible dynamic effects of sugars have on lipid membranes.