title: Effect of the fluorination degree of hydrophobic chains on the monolayer behavior of unsaturated diacylphosphatidylcholines bearing partially fluorinated 9-octadecynoyl (stearoloyl) groups at the air-water interface.
abstract: The effect of the fluorination degree of hydrophobic chains on the monolayer behavior of unsaturated diacylphosphatidylcholines (PCs) was examined by employing a series of PCs bearing partially fluorinated 9-octadecynoyl (stearoloyl) groups (DFnStPCs, n: the number of fluorinated carbon atoms in a stearoloyl group; n=1, 2, 4, 8), including their hydrophobic parts--partially fluorinated stearolic acids (FnStAs)--at the air-water interface. π-A isotherm measurements and Brewster angle microscope observations revealed: (i) all DFnStPCs including FnStAs form monolayers of liquid character at 25 °C; (ii) they form more expanded monolayers than their non-fluorinated counterparts, distearoloyl-PC (DStPC) and stearolic acid, while the monolayer stability increases with n; (iii) compared with DStPC and DF8StPC, DFnStPCs (n=1, 2, 4) in the low-π region tend to show a weakening in their self-aggregation property and an increase in the work required for monolayer compression; (iv) although DF8StPC forms the most expanded monolayer, the behavior of DF8StPC resembles that of DStPC rather than that of DFnStPCs (n=1, 2, 4). The monolayer behavior of DFnStPCs (n=1, 2, 4) is explained by postulating a flatly-lying conformation of hydrophobic chains, in which three polar parts (ester group, triple bond, CF2-CH2 linkage) in chains are immersed in the subphase at large areas. DStPC and DF8StPC lacking a CF2-CH2 linkage, however, do not likely adopt such a conformation.
authors.affiliation: Research Center of Advanced Bionics (RCAB), National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan. Electronic address: t-baba@aist.go.jp.
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Baba
authors.affiliation: Research Center of Advanced Bionics (RCAB), National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan.
authors.forename: Katsuki
authors.initials: K
authors.lastname: Takai
authors.affiliation: Research Center of Advanced Bionics (RCAB), National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Takagi
authors.affiliation: Research Center of Advanced Bionics (RCAB), National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kanamori
mesh_terms: D000388:Air; D057927:Hydrophobic and Hydrophilic Interactions; D008962:Models, Theoretical; D010713:Phosphatidylcholines / Q000737:chemistry*; D014867:Water
chemical_list: D010713:Phosphatidylcholines; D014867:Water
keywords: Brewster angle microscope; Equation of state; Fluorinated phosphatidylcholine; Monolayer stability; Stearolic acid; π–A isotherm