Direct electrochemistry of cytochrome c immobilized on titanium nitride/multi-walled carbon nanotube composite for amperometric nitrite biosensor

In this report, titanium nitride (TiN) nanoparticles decorated multi-walled carbon nanotube (MWCNTs) nanocomposite is fabricated via a two-step process. These two steps involve the decoration of titanium dioxide nanoparticles onto the MWCNTs surface and a subsequent thermal nitridation. Transmission electron microscopy shows that TiN nanoparticles with a mean diameter of <= 20 nm are homogeneously dispersed onto the MWCNTs surface. Direct electrochemistry and electrocatalysis of cytochrome c immobilized on the MWCNTs-TiN composite modified on a glassy carbon electrode for nitrite sensing are investigated. Under optimum conditions, the current response is linear to its concentration from 1 PA to 2000 mu M with a sensitivity of 121.5 mu A mu M-1 cm(-2) and a low detection limit of 0.0014 mu M. The proposed electrode shows good reproducibility and long-term stability. The applicability of the as-prepared biosensor is validated by the successful detection of nitrite in tap and sea water samples. (C) 2015 Elsevier B.V. All rights reserved.