title: Formation of substrate-supported membranes from mixtures of long- and short-chain phospholipids.
abstract: We studied the formation of substrate-supported planar phospholipid bilayers (SPBs) on glass and silica from mixtures of long- and short-chain phospholipids to assess the effects of detergent additives on SPB formation. 1,2-Hexyanoyl-sn-glycero-3-phosphocholine (DHPC-C6) and 1,2-heptanoyl-sn-glycero-3-phosphocholine (DHPC-C7) were chosen as short-chain phospholipids. 1-Palmitoyl-2-oleol-sn-glycero-3-phosphocholine (POPC) was used as a model long-chain phospholipid. Kinetic studies by quartz crystal microbalance with dissipation monitoring (QCM-D) showed that the presence of short-chain phospholipids significantly accelerated the formation of SPBs. Rapid rinsing with a buffer solution did not change the adsorbed mass on the surface if POPC/DHPC-C6 mixtures were used below the critical micelle concentration (cmc) of DHPC-C6, indicating that an SPB composed of POPC molecules remained on the surface. Fluorescence microscopy observation showed homogeneous SPBs, and the fluorescence recovery after photobleaching (FRAP) measurements gave a diffusion coefficient comparable to that for SPBs formed from POPC vesicles. However, mixtures of POPC/DHPC-C7 resulted in a smaller mass of lipid adsorption on the substrate. FRAP measurements also yielded significantly smaller diffusion coefficients, suggesting the presence of defects. The different behaviors for DHPC-C6 and DHPC-C7 point to the dual roles of detergents to enhance the formation of SPBs and to destabilize them, depending on their structures and aggregation properties.
authors.affiliation: Research Center for Environmental Genomics, Kobe University, Rokkodaicho 1-1, Nada, Kobe 657-8501 Japan. morigaki@port.kobe-u.ac.jp
authors.forename: Kenichi
authors.initials: K
authors.lastname: Morigaki
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kimura
authors.forename: Keisuke
authors.initials: K
authors.lastname: Okada
authors.forename: Takashi
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kawasaki
mesh_terms: D000327:Adsorption; D002462:Cell Membrane / Q000737:chemistry*; D055598:Chemical Phenomena; D003902:Detergents / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009038:Motion; D010743:Phospholipids / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D003902:Detergents; D008051:Lipid Bilayers; D010743:Phospholipids; D012822:Silicon Dioxide