Atomic Force Microscopy Study of Model Lipid Monolayers

[摘要] Alzheimer;;s Disease (AD) is a neurodegenerative disorder that is prevalent among the elderly population. Aß protein has been heavily implicated in the pathogenesis of AD. This protein in its fibrillar form is a major component in the senile plaques that form on neuronal cellular membranes during the course of AD. Despite substantial efforts the exact mechanism of Aß toxicity towards a cell membrane is not well-understood. The determination of this mechanism, however, is of utmost importance, since the membrane presents thefirst site of Aß interaction with neurons, which in turn maybe the origin of Aß neurotoxicity. The purpose of this study was to find a lipid composition that can be used as a model of neuronal membrane for subsequent studies of the role of topographical heterogeneity(domain formation) on Aß-membrane interaction as related to AD. The lipids used in the study were 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG), cholesterol (Chol), sphingomyelin (SM) and ganglioside GM1 (GM1). These lipids were combined in different proportions and depositedon a mica substrate to form supported monolayers. They were then imaged with an atomic force microscope (AFM) to determine if any of them exhibited domain formation. Three of the studied samples: POPC/POPG/SM 40:40:20 +5%Chol, POPC/SM/Chol 75:20:5and POPC/SM/GM1/Chol 74:2:1:23 were found to possess interesting topography, rich instructural features: pores and domains. The average height difference between the domainfeatures for each sample was found to be 0.58±015 nm, 0.61±0.12 nm and 0.27±0:07 nm.

[发布机构] University of Waterloo

[效力级别] Lipid Monolayers

[关键词] Atomic force microscopy;Lipid Monolayers;Physics