title: Superoxide radical biosensor based on a nano-composite containing cytochrome c.
abstract: A biosensor for the quantification of superoxide radical (O(2)˙(-)) was developed based on a nano-composite containing cytochrome c (Cyt c), carboxylated multi-walled carbon nanotubes and a room temperature ionic liquid (RTIL). The immobilized Cyt c was characterized by field emission scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. Using this biosensor a formal potential of -280 mV (vs. Ag/AgCl) and electron transfer rate constant of 1.24 was recorded for the immobilized Cyt c in 0.1 M phosphate buffer solution (pH 7.0). The biosensor showed a relatively high sensitivity (7.455 A M(-1) cm(-2)) and a long term stability (180 days) towards O(2)˙(-) in the concentration range from 0.05 to 8.1 μM with a detection limit of 0.03 μM. The selectivity of the biosensor to O(2)˙(-) was verified when its response was compared with those obtained by four potential interfering substances (ascorbic acid, uric acid, acetaminophen and hydrogen peroxide).
authors.affiliation: Laboratory of Microanalysis, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
authors.forename: Parvaneh
authors.initials: P
authors.lastname: Rahimi
authors.forename: Hedayatollah
authors.initials: H
authors.lastname: Ghourchian
authors.forename: Hossain-Ali
authors.initials: HA
authors.lastname: Rafiee-Pour
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism; D004566:Electrodes; D004579:Electron Transport; D004800:Enzymes, Immobilized / Q000737:chemistry; D006736:Horses; D052578:Ionic Liquids / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry*; D013481:Superoxides / Q000032:analysis*
chemical_list: D004800:Enzymes, Immobilized; D052578:Ionic Liquids; D037742:Nanotubes, Carbon; D013481:Superoxides; D045304:Cytochromes c