title: Enzyme immobilization on poly(ethylene-co-acrylic acid) films studied by quartz crystal microbalance with dissipation monitoring.
abstract: In this study, we use the quartz crystal microbalance with dissipation monitoring (QCM-D) to study the immobilization of the enzyme horseradish peroxidase (HRP) on poly(ethylene-co-acrylic acid) (PEAA) films. The surface polarity of spin-coated PEAA films was varied by heat treatments in air or in a 30% NaOH aqueous solution leading to COOH-depleted or COOH-enriched surfaces, respectively. Two reaction schemes, direct adsorption and amine coupling, were employed for HRP immobilization on the two surfaces. The shifts in frequency and dissipation, Deltaf and DeltaD, measured by QCM-D and the ratio DeltaD/Deltaf were used to evaluate the binding amount and the conformation of the adsorbed enzyme. It is found that HRP immobilized via covalent linkages forms rigid and little dissipative films. In contrast, directly adsorbed HRP films exhibit a highly dissipative structure. HRP-catalyzed oxidation of the 4-chloro-1-naphthol in the presence of H(2)O(2) was used to characterize the catalytic activity of the HRP films. The results show that the enzymatic activity of the covalently immobilized HRP tends to be higher.
authors.affiliation: Institute of Materials Research and Engineering, 3 Research Link, 117602 Singapore. xd-su@imre.a-star.edu.sg
authors.forename: Xiaodi
authors.initials: X
authors.lastname: Su
authors.forename: Yun
authors.initials: Y
authors.lastname: Zong
authors.forename: Ralf
authors.initials: R
authors.lastname: Richter
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Knoll
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D004800:Enzymes, Immobilized / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry*; D008422:Materials Testing; D011095:Polyethylenes / Q000737:chemistry*; D011791:Quartz / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000180:Acrylic Resins; D004800:Enzymes, Immobilized; D011095:Polyethylenes; D011791:Quartz; C083316:(polyethylene-acrylic acid) copolymer; D006735:Horseradish Peroxidase