Direct electrochemistry of hemoglobin and its biosensing for hydrogen peroxide on TiO 2 –polystyrene nanofilms

Nanofilms of titanium dioxide (TiO 2 ) nanoparticles that mediate the assembly of polystyrene (PS) nanoparticles for immobilizing hemoglobin (Hb) on carbon ionic liquid electrode have been developed. Fourier transform infrared spectroscopy shows that Hb retains its native structure in TiO 2 –PS nanofilms. Scanning electron microscopy reveals that the nanofilms possess uniform morphology and Hb is immobilized on the surface of the nanofilms. Electrochemical investigation of the biosensor indicates that the direct electrochemistry of hemoglobin is realized on the nanofilms, and there is a formal potential of −0.320 V in deaerated buffer solutions; the biosensor shows good electrocatalytic activity toward the reduction of hydrogen peroxide with a linear range from 0.5 to 640 μM, a detection limit of 0.2 μM ( S / N = 3) and a sensitivity of 103 μA mM −1 . Thus, the nanofilms will have potential application in the design of novel electrochemical biosensors.