title: Building Polyelectrolyte Multilayers with Calmodulin: A Neutron and X-ray Reflectivity Study.
abstract: We have studied the formation and functional properties of polyelectrolyte multilayers where calmodulin (CaM) is used as a polyanion. CaM is known to populate distinct conformational states upon binding Ca2+and small ligand molecules. Therefore, we have also probed the effects of Ca2+ions and trifluoperazine (TFP) as ligand molecule on the interfacial structures. Multilayers with the maximum sequence PEI-(PSS-PAH)x-CaM-PAH-CaM-PAH have been deposited on silicon wafers and characterized by X-ray and neutron reflectometry. From the analysis of all data, several remarkable conclusions can be drawn. When CaM is deposited for the second time, a much thicker sublayer is produced than in the first CaM deposition step. However, upon rinsing with PAH, very thin CaM-PAH sublayers remain. There are no indications that ligand TFP can be involved in the multilayer buildup due to strong CaM-PAH interactions. However, there is a significant increase in the multilayer thickness upon removal of Ca2+ions from holo-CaM and an equivalent decrease in the multilayer thickness upon subsequent saturation of apo-CaM with Ca2+ions. Presumably, CaM can still be toggled between an apo and a holo state, when it is embedded in polyelectrolyte multilayers, providing an approach to design bioresponsive interfaces.
authors.affiliation: Department of Chemistry and Chemical Biology, TU Dortmund University , D-44221 Dortmund, Germany.
authors.forename: Süleyman
authors.initials: S
authors.lastname: Cinar
authors.affiliation: Department of Chemistry and Chemical Biology, TU Dortmund University , D-44221 Dortmund, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Möbitz
authors.affiliation: Department of Chemistry and Chemical Biology, TU Dortmund University , D-44221 Dortmund, Germany.
authors.forename: Samy
authors.initials: S
authors.lastname: Al-Ayoubi
authors.affiliation: Helmholtz-Zentrum Berlin, D-14109 Berlin, Germany.
authors.forename: Beatrix-Kamelia
authors.initials: BK
authors.lastname: Seidlhofer
authors.affiliation: Department of Chemistry and Chemical Biology, TU Dortmund University , D-44221 Dortmund, Germany.
authors.forename: Claus
authors.identifier: 0000-0003-0612-3602
authors.initials: C
authors.lastname: Czeslik