title: Templating α-helical poly(L-lysine)/polyanion complexes by nanostructured uniaxially oriented ultrathin polyethylene films.
abstract: We report a templating effect of uniaxially oriented melt-drawn polyethylene (MD-PE) films on α-helical poly(L-lysine)/poly(styrenesulfonate) (α-PLL/PSS) complexes deposited by the layer-by-layer (LBL) method. The melt-drawing process induced an MD-PE fiber texture consisting of nanoscale lamellar crystals embedded in amorphous regions on the MD-PE film surface whereby the common crystallographic c axis is the PE molecular chain direction parallel to the uniaxial melt-drawing direction. The MD-PE film and the α-PLL/PSS deposit were analyzed by atomic force microscopy (AFM) and in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) using polarized light as a complementary method. Both methods revealed that α-PLL/PSS complexes adsorbed at the MD-PE surface were anisotropic and preferentially oriented perpendicular to the crystallographic c direction of the MD-PE film. Quantitatively, from AFM image analysis and ATR-FTIR dichroism of the amide II band of the α-PLL, mean cone opening angles of 12-18° for both rodlike α-PLL and the anisotropic α-PLL/PSS complexes with respect to the PE lamellae width direction were obtained. A model for the preferred alignment of α-PLL along the protruding PE lamellae is discussed, which is based on possible hydrophobic driving forces for the minimization of surface free energy at molecular and supermolecular topographic steps of the PE surface followed by electrostatic interactions between the interconnecting PSS and the α-PLL during layer-by-layer adsorption. This study elucidates the requirements and mechanisms involved in orienting biomolecules and may open up a path for designing templates to induce directed protein adsorption and cell growth by oriented polypeptide- or protein-modified PE surfaces.
authors.affiliation: Institute of Materials Science & Technology, Friedrich-Schiller-University Jena, Löbdergraben 32, D-07743 Jena, Germany.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Keller
authors.forename: Martin
authors.initials: M
authors.lastname: Müller
authors.forename: Wuye
authors.initials: W
authors.lastname: Ouyang
authors.forename: Jian-Tao
authors.initials: JT
authors.lastname: Zhang
authors.forename: Klaus D
authors.initials: KD
authors.lastname: Jandt
mesh_terms: D003460:Crystallization; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry*; D020959:Polyethylene / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D011137:Polystyrenes; D011107:Polylysine; C003321:polystyrene sulfonic acid; D020959:Polyethylene