title: Direct electron transfer and electrocatalysis of hemoglobin in ZnO coated multiwalled carbon nanotubes and Nafion composite matrix.
abstract: ZnO coated multiwalled carbon nanotubes (ZnO-MWCNTs) nano-composite was synthesized by the hydrothermal method and expected to offer a promising template for biosensor fabrication due to satisfying biocompatibility and improved properties. The ZnO-MWCNTs nano-composite was mixed with Nafion solution to form a composite matrix for the fabrication of hemoglobin (Hb) biosensor. This composite matrix combined the advantages of inorganic composite (ZnO-MWCNTs) and organic polymer (Nafion) and could promote the direct electron transfer of Hb. The Hb/ZnO-MWCNTs/Nafion film exhibited a pair of well-defined, quasi-reversible redox peaks with a formal potential of -0.353V (vs. SCE), characteristic of heme redox couple (Fe(III)/Fe(II)) of Hb. Hb retained its near-native conformation in the composite film. The immobilized Hb showed fast and excellent electrocatalytic activity to H(2)O(2) with a linear range from 2x10(-7) to 1.2x10(-5)M, and the detection limit was 8.4x10(-8)M. The sensitivity and apparent Michaelis-Menten constant were 1.31A/(M x cm(2)) and 82.8microM, respectively, which indicated that Hb had a high affinity to H(2)O(2). This biosensor also showed excellent electrocatalytic activity towards trichloroacetic acid.
authors.affiliation: College of Science, Nanjing University of Technology, Nanjing 210009, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.forename: Danbi
authors.initials: D
authors.lastname: Tian
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002384:Catalysis; D002417:Cattle; D004563:Electrochemistry; D004566:Electrodes; D004579:Electron Transport; D005465:Fluorocarbon Polymers / Q000737:chemistry*; D005898:Glass / Q000737:chemistry; D006454:Hemoglobins / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D055767:Immobilized Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D053761:Nanocomposites / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D015203:Reproducibility of Results; D013057:Spectrum Analysis; D014238:Trichloroacetic Acid / Q000378:metabolism; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D005465:Fluorocarbon Polymers; D006454:Hemoglobins; D055767:Immobilized Proteins; D037742:Nanotubes, Carbon; C040402:perfluorosulfonic acid; D014238:Trichloroacetic Acid; D006861:Hydrogen Peroxide; D015034:Zinc Oxide