Direct electrochemistry of cytochrome c with three-dimensional nanoarchitectured multicomponent composite electrode and nitrite biosensing

A novel electrochemical nitrite ion (NO2-) biosensor was designed and fabricated by modifying a glassy carbon electrode (GCE) into three-dimensional nanoarchitectured electrode (3DNE) using a multicomponent nanocompo site (MCNC) film composed of graphene embedded titanium dioxide nanowires (TiO2(G) NWs), thiol-functionalized polyaniline (PANI(SH)), gold nanoparticles (Au), and immobilized cytochrome c (cyt c). The new NO2- biosensor was designated as cyt c/TiO2(G) NWs@PANI(SH)-Au MCNC/3DNE. The assembly of the 3DNE, involved sequential depositions of PANI(SH) and Au over previously synthesized TiO2(G) NWs by electrospinning-hydrothermal processes and immobilization of the cyt c onto the TiO2(G) NWs/PANI(SH)/Au MCNC film. The cyt c/TiO2(G) NWs@PANI(SH)-Au MCNC/3DNE exhibited direct electron transfer from cyt c to the electrode at a high rate constant (25.34 s(-1)). The fabricated cyt c/TiO2(G) NWs@PANI(SH)-Au