title: Ammonia plasma treated polyethylene films for adsorption or covalent immobilization of trypsin: quantitative correlation between X-ray photoelectron spectroscopy data and enzyme activity.
abstract: The ammonia plasma process was used for generating reactive groups, particularly primary amine functions on the surface of polyethylene (PE) films, to immobilize the enzyme trypsin. The attachment of the enzyme was achieved by directly applying an aqueous solution of trypsin to the plasma-activated surface or by using glutaraldehyde as a chemical linker. In both cases, the utilization of sodium cyanoborohydride efficiently stabilized the immobilization. The surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) and enzymatic activity measurements. Active trypsin was successfully immobilized on the surface with a mean activity of 0.09 ± 0.02 U/cm(2). The study of the stability of the immobilized enzyme during repetitive assays showed that some activity could be maintained during several months. An original quantitative correlation between the immobilized enzyme activity and the XPS signal intensity of the S 2p electrons present in the sulfur-containing amino acid residues was evidenced.
authors.affiliation: Chimie ParisTech, Laboratoire de Génie des Procédés Plasma et Traitements de Surface (LGPPTS), EA 3492, 75005 Paris, France. mahsa-ghasemi@chimie-paristech.fr
authors.forename: Mahsa
authors.initials: M
authors.lastname: Ghasemi
authors.forename: Michel J G
authors.initials: MJ
authors.lastname: Minier
authors.forename: Michaël
authors.initials: M
authors.lastname: Tatoulian
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Chehimi
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Arefi-Khonsari
mesh_terms: D000327:Adsorption; D000641:Ammonia / Q000737:chemistry*; D000818:Animals; D002417:Cattle; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D005976:Glutaral / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D058626:Plasma Gases / Q000737:chemistry*; D020959:Polyethylene / Q000737:chemistry*; D015203:Reproducibility of Results; D013499:Surface Properties; D014357:Trypsin / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D058626:Plasma Gases; D000641:Ammonia; D020959:Polyethylene; D014357:Trypsin; D005976:Glutaral