title: Direct electrochemistry and electrocatalysis of hemoglobin immobilized in a magnetic nanoparticles-chitosan film.
abstract: Magnetic nanoparticles (Fe(3)O(4)) were synthesized by a chemical coprecipitation method. X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to confirm the crystallite structure and the particle's radius. The Fe(3)O(4) nanoparticles and chitosan (CS) were mixed to form a matrix in which haemoglobin (Hb) can be immobilized for the fabrication of H(2)O(2) biosensor. The Fe(3)O(4)-CS-Hb film exhibited a pair of well-defined and quasi-reversible cyclic voltammetric peaks due to the redox of Hb-heme Fe (III)/Fe (II) in a pH 7.0 phosphate buffer. The formal potential of Hb-heme Fe(III)/Fe(II) couple varied linearly with the increase of pH in the range of 4.0-10.0 with a slope of 46.5 mV pH(-1), indicating that electron transfer was accompanied with single proton transportation in the electrochemical reaction. The surface coverage of Hb immobilized on Fe(3)O(4)-CS film glassy carbon electrode was about 1.13 x 10(-10)mol cm(-2). The heterogeneous electron transfer rate constant (k(s)) was 1.04 s(-1), indicating great facilitation of the electron transfer between Hb and magnetic nanoparticles-chitosan modified electrode. The modified electrode showed excellent electrocatalytic activity toward oxygen and hydrogen peroxide reduction. The apparent Michaelis-Menten constant K(M)(app) for H(2)O(2) was estimated to be 38.1 micromol L(-1).
authors: College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Na
authors: N
authors: Zheng
authors: Xia
authors: X
authors: Zhou
authors: Weiying
authors: W
authors: Yang
authors: Xiangjun
authors: X
authors: Li
authors: Zhuobin
authors: Z
authors: Yuan
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D002384:Catalysis; D002417:Cattle; D048271:Chitosan / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D004579:Electron Transport; D052203:Ferrosoferric Oxide / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000032:analysis / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D055767:Immobilized Proteins / Q000737:chemistry* / Q000378:metabolism; D008280:Magnetics; D053758:Nanoparticles / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D017433:Protein Structure, Secondary; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D006454:Hemoglobins; D055767:Immobilized Proteins; D048271:Chitosan; D006861:Hydrogen Peroxide; D010100:Oxygen; D052203:Ferrosoferric Oxide