Direct electrochemistry of hemoglobin/peptide-carbon nanotube modified electrode for hydrogen peroxide biosensing

Mediatorless enzymatic biosensors based on direct electron transfer show promise due to their high stability and remarkable electrocatalytical performance. In this study, the direct electrochemistry of a glassy carbon electrode modified with hemoglobin (Hb) embedded in a hybrid layer of self-assembling EFK8 peptide and single-walled carbon nanotubes (SWNTs) was investigated. Electrochemical studies in 0.1 M phosphate buffer (PB) revealed that the immobilized Hb did not denature and retained its bio-catalytic activity. The resulting biosensor was used to detect and measure the hydrogen peroxide (H2O2) concentration in 0.1 M PB (pH 7.0), yielding a linear detection range from 20 to 960 mu M and a detection limit of 7.54 mu M (S/N = 3). The EFK8-SWNT hybrid layer shows promise as a biocompatible layer for simple non-covalent enzyme immobilization as the basis for future mediatorless enzymatic biosensors.