title: Glassy carbon electrode modified with horse radish peroxidase/organic nucleophilic-functionalized carbon nanotube composite for enhanced electrocatalytic oxidation and efficient voltammetric sensing of levodopa.
abstract: A novel and selective enzymatic biosensor was designed and constructed for voltammetric determination of levodopa (L-Dopa) in aqueous media (phosphate buffer solution, pH=7). Biosensor development was on the basis of to physically immobilizing of horse radish peroxidase (HRP) as electrochemical catalyst by sol-gel on glassy carbon electrode modified with organic nucleophilic carbon nanotube composite which in this composite p-phenylenediamine (pPDA) as organic nucleophile chemically bonded with functionalized MWCNT (MWCNT-COOH). The results of this study suggest that prepared bioorganic nucleophilic carbon nanotube composite (HRP/MWCNT-pPDA) shows fast electron transfer rate for electro oxidation of L-Dopa because of its high electrochemical catalytic activity toward the oxidation of L-Dopa, more--NH2 reactive sites and large effective surface area. Also in this work we measured L-Dopa in the presence of folic acid and uric acid as interferences. The proposed biosensor was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), FT-IR spectroscopy and cyclic voltammetry (CV). The differential pulse voltammetry (DPV) was used for determination of L-Dopa from 0.1 μM to 1.9 μM with a low detection limit of 40 nM (for S/N=3) and sensitivity was about 35.5 μA/μM. Also this biosensor has several advantages such as rapid response, high stability and reproducibility.
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, P.O. Box, 65174, Hamedan, Iran.
authors.forename: Yalda
authors.initials: Y
authors.lastname: Shoja
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, P.O. Box, 65174, Hamedan, Iran. Electronic address: aa_rafati@basu.ac.ir.
authors.forename: Amir Abbas
authors.initials: AA
authors.lastname: Rafati
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, P.O. Box, 65174, Hamedan, Iran.
authors.forename: Javad
authors.initials: J
authors.lastname: Ghodsi
mesh_terms: D015374:Biosensing Techniques; D002138:Calibration; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D005898:Glass / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007980:Levodopa / Q000032:analysis*; D057230:Limit of Detection; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D010655:Phenylenediamines; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D037742:Nanotubes, Carbon; D010655:Phenylenediamines; D007980:Levodopa; D002244:Carbon; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; C029728:4-phenylenediamine
keywords: Carbon nanotube; HRP biosensor; Levodopa; Nucleophilic functionalized carbon nanotube; p-Phenylynediamine