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Immobilization of myoglobin on Au nanoparticle-decorated carbon nanotube/polytyramine composite as a mediator-free H2O2 and nitrite biosensor.

ABSTRACT: A novel composite film was designed for use as a highly selective mediator-free amperometric biosensor, and a method was created for accomplishing direct electrochemistry of myoglobin on a multi-walled carbon nanotube and tyramine-modified composite decorated with Au nanoparticles on a glassy carbon electrode. The ultraviolet-visible and electrochemical impedance spectroscopy results showed that myoglobin retained its native conformation in the interaction with Au-PTy-f-MWCNT. The surface coverage of Mb-heme-Fe((II)/(III)) immobilized on Au-PTy-f-MWCNT and the heterogeneous electron-transfer rate constant were 2.12 × 10(-9) mol cm(-2) and 4.86 s(-1), respectively, indicating a higher loading capacity of the nanocomposite for direct electron transfer of Mb onto the electrode surface. The proposed Mb/Au-PTy-f-MWCNT biofilm exhibited excellent electrocatalytic behavior toward the reduction of H2O2 and the oxidation of nitrite with linear ranges of 2 to 5000 μM and 1 to 8000 μM and lower detection limits of 0.01 μM and 0.002 μM, respectively. An apparent Michaelis-Menten constant of 0.12 mM indicated that the Mb immobilized on the Au-PTy-f-MWCNT film retained its native activity. This biosensor can be successfully applied to detect H2O2 and nitrite in disinfectant cream, eye drops, pickle juice, and milk samples.

SUBMITTER: Vilian AT

PROVIDER: S-EPMC4682093 | biostudies-literature |

REPOSITORIES: biostudies-literature

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