title: Adsorption of lysozyme on base metal surfaces in the presence of an external electric potential.
abstract: The impact of external electric potential on the adsorption of a protein to base metal surfaces was examined. Hen egg white lysozyme (LSZ) and six types of base metal plates (stainless steel SUS316L (St), Ti, Ta, Zr, Cr, or Ni) were used as the protein and adsorption surface, respectively. LSZ was allowed to adsorb on the surface under different conditions (surface potential, pH, electrolyte type and concentration, surface material), which was monitored using an ellipsometer. LSZ adsorption was minimized in the potential range above a certain threshold and, in the surface potential range below the threshold, decreasing the surface potential increased the amount of protein adsorbed. The threshold potential for LSZ adsorption was shifted toward a positive value with increasing pH and was lower for Ta and Zr than for the others. A divalent anion salt (K2SO4) as an electrolyte exhibited the adsorption of LSZ in the positive potential range while a monovalent salt (KCl) did not. A comprehensive consideration of the obtained results suggests that two modes of interactions, namely the electric force by an external electric field and electrostatic interactions with ionized surface hydroxyl groups, act on the LSZ molecules and determine the extent of suppression of LSZ adsorption. All these findings appear to support the view that a base metal surface can be controlled for the affinity to a protein by manipulating the surface electric potential as has been reported on some electrode materials.
authors.affiliation: Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Htwe
authors.initials: H
authors.lastname: Ei Ei
authors.affiliation: Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Yuhi
authors.initials: Y
authors.lastname: Nakama
authors.affiliation: Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Imanaka
authors.affiliation: Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Ishida
authors.affiliation: Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan. Electronic address: kore@cc.okayama-u.ac.jp.
authors.forename: Koreyoshi
authors.initials: K
authors.lastname: Imamura
mesh_terms: D000327:Adsorption; D000818:Animals; D002645:Chickens; D005260:Female; D008670:Metals / Q000737:chemistry*; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D008670:Metals; C421864:hen egg lysozyme; D009113:Muramidase
keywords: Adsorption; Electrostatic interaction; Ellipsometer; External electric potential; Lysozyme; Metal oxide; Surface hydroxyl group