title: Helical carbon nanotubes: intrinsic peroxidase catalytic activity and its application for biocatalysis and biosensing.
abstract: A combined hydrothermal/hydrogen reduction method has been developed for the mass production of helical carbon nanotubes (HCNTs) by the pyrolysis of acetylene at 475 °C in the presence of Fe(3)O(4) nanoparticles. The synthesized HCNTs have been characterized by high-resolution transmission electron microscopy, scanning electron microscopy, X-ray diffraction analysis, vibrating sample magnetometry, and contact-angle measurements. The as-prepared helical-structured carbon nanotubes have a large specific surface area and high peroxidase-like activity. Catalysis was found to follow Michaelis-Menten kinetics and the HCNTs showed strong affinity for both H(2)O(2) and 3,3',5,5',-tetramethylbenzidine (TMB). Based on the high activity, the HCNTs were firstly used to develop a biocatalyst and amperometric sensor. At pH 7.0, the constructed amperometric sensor showed a linear range for the detection of H(2)O(2) from 0.5 to 115 μM with a correlation coefficient of 0.999 without the need for an electron-transfer mediator. Because of their low cost and high stability, these novel metallic HCNTs represent a promising candidate as mimetic enzymes and may find a wide range of new applications, such as in biocatalysis, immunoassay, and environmental monitoring.
authors.affiliation: Key Laboratory of Analytical Chemistry for Life Science (MOE), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Rongjing
authors.initials: R
authors.lastname: Cui
authors.forename: Zhida
authors.initials: Z
authors.lastname: Han
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Zhu
mesh_terms: D001560:Benzidines / Q000032:analysis / Q000378:metabolism*; D055162:Biocatalysis; D032701:Biomimetics / Q000295:instrumentation / Q000379:methods*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D006861:Hydrogen Peroxide / Q000032:analysis / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008839:Microelectrodes; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D018716:Molecular Mimicry; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D001560:Benzidines; D037742:Nanotubes, Carbon; C021758:3,3',5,5'-tetramethylbenzidine; D006861:Hydrogen Peroxide; D009195:Peroxidase