CARBONLETT, vol. 24, no. 1, pp.103-110, 2017

DOI: http://dx.doi.org/10.5714/CL.

Synthesis and physicochemical characterization of Ni_xZn_x- Fe₂O₄/MWCNT nanostructures as enzyme mimetics with peroxidase-like catalytic activity

Navvabeh Salarizadeh¹, Minoo Sadri^1,♠, Hassan Hosseini² and Reza. H. Sajedi³

Affiliation: ¹Department of Biochemistry and Biophysics, Education and Research Center of Science and Biotechnology, Malek Ashtar University of Technology, Tehran 16765-3454, Iran
²Department of Chemistry, Faculty of Sciences, Imam Hossein University, Tehran 16575-347, Iran
³Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran 14115-175, Iran

Abstract: Carbon-based magnetic nanostructures in several instances have resulted in improved physicochemical and catalytic properties when compared to multi-wall carbon nanotubes (MWCNTs) and magnetic nanoparticles. In this study, magnetic MWCNTs with a structure of Ni_xZn_x- Fe₂O₄/MWCNT as peroxidase mimics were fabricated by the one-pot hydrothermal method. The structure, composition and morphology of the nanocomposites were characterized with X-ray diffraction (XRD), Fourier transform infrared spectroscopy and transmission electron microscopy. The magnetic properties were investigated with a vibrating sample magnetometer. The peroxidase-like catalytic activity of the nanocomposites was investigated by colorimetric and electrochemical tests with 3,3´,5,5´-tetramethylbenzidine (TMB) and H2O2 as the substrates. The results show that the synthesis of the nanocomposites was successfully performed. XRD analysis confirmed the crystalline structures of the Ni_xZn_x- Fe₂O₄/MWCNT nanohybrids and MWCNTs. The main peaks of the Ni_xZn_x- Fe₂O₄/MWCNTs crystals were presented. The Ni_0.25Zn_0.25Fe₂O₄/MWCNT and Ni_0.5Zn_0.5Fe₂O₄/MWCNT nanocatalysts showed nearly similar physicochemical properties, but the Ni_0.5Zn_0.5Fe₂O₄/MWCNT nanocatalyst was more appropriate than the Ni_0.25Zn_0.25Fe₂O₄/MWCNT nanocatalyst in terms of the magnetic properties and catalytic activity. The optimum peroxidase-like activity of the nanocatalysts was obtained at pH 3.0. The Ni_0.5Zn_0.5Fe₂O₄/MWCNT nanocatalyst exhibited a good peroxidase-like activity. These magnetic nanocatalysts can be suitable candidates for future enzyme-based applications such as the detection of glucose and H₂O₂.

Keyword: magnetic carbon nanotubes, peroxidase-like activity, characterization, biomimetic catalysts