title: Monolayers of poly-L-lysine on mica--Electrokinetic characteristics.
abstract: Physicochemical properties of poly-l-lysine and its monolayers on mica were thoroughly investigated by dynamic light scattering, electrokinetic methods and atomic force microscopy. The hydrodynamic diameter of PLL was equal to 25.5 nm within a wide range of pH and ionic strength. The electrophoretic measurements revealed that the molecules are positively charged for pH<10.5. By exploiting the electrophoretic mobility data, theelectrokinetic charge on the PLL molecules and their zeta potential were calculated. PLL monolayers of controlled coverage were deposited on mica under diffusion-controlled conditions by varying PLL bulk concentration and adsorption time. The electrokinetic characteristics of the monolayers were acquired in situ via streaming potential measurements. These studies allowed to uniquely determine the zeta potential of the monolayers as a function of pH and ionic strength. In this way the isoelectric point of the monolayers can be determined in a more convenient way compared to bulk measurements disturbed by the PLL molecule interactions. The stability of the monolayers under flow conditions was quantitatively evaluated via streaming potential measurements. The adsorption constant and the binding energy depth of PLL molecules were determined for different ionic strengths. These parameters indicate that the PLL monolayers remain stable over prolonged times.
authors.affiliation: Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Cracow, Poland. Electronic address: ncmorga@cyf-kr.edu.pl.
authors.forename: Maria
authors.initials: M
authors.lastname: Morga
authors.affiliation: Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Cracow, Poland. Electronic address: ncadamcz@cyf-kr.edu.pl.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Adamczyk
authors.affiliation: Department of Physical Chemistry II, University of Bayreuth, Universitätsstraβe 30, 95447 Bayreuth, Germany. Electronic address: Sebastian.Goedrich@uni-bayreuth.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Gödrich
authors.affiliation: Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Cracow, Poland. Electronic address: ncocwiej@cyf-kr.edu.pl.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Oćwieja
authors.affiliation: Department of Physical Chemistry II, University of Bayreuth, Universitätsstraβe 30, 95447 Bayreuth, Germany. Electronic address: Georg.Papastavrou@uni-bayreuth.de.
authors.forename: Georg
authors.initials: G
authors.lastname: Papastavrou
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods; D004573:Electrolytes; D004867:Equipment Design; D057446:Hydrodynamics; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D018625:Microscopy, Atomic Force; D009994:Osmolar Concentration; D011107:Polylysine / Q000737:chemistry*; D012542:Scattering, Radiation; D013499:Surface Properties; D013997:Time Factors; D014783:Viscosity
chemical_list: D000538:Aluminum Silicates; D004573:Electrolytes; D011107:Polylysine; C011934:mica
keywords: Adsorption of poly-l-lysine on mica; Electrokinetic characteristics of poly-l-lysine molecules; Electrokinetics of poly-l-lysine monolayers; Poly-l-lysine monolayers at mica; Stability of poly-l-lysine monolayers at mica; Zeta potential of poly-l-lysine monolayers at mica