Novel amperometric biosensor based on composite film assembled by polyelectrolyte-surfactant polymer, carbon nanotubes and hemoglobin

A novel hydrogen peroxide biosensor has been developed based on the encapsulation of hemoglobin (Hb) in the composite film of carboxylic carbon nanotubes and polyelectrolyte-surfactant polymer. The direct electron transfer of the Hb entrapped in the composite film was observed. The formal potential of the encapsulated Hb was −0.287 V versus SCE and the heterogeneous electron transfer rate constant was 0.4 s−1 in a 0.1 M phosphate buffer solution (pH 7.0). An FT-IR spectroscopy study confirms that the secondary structure of Hb encapsulated in the composite film still retains the original arrangement. It is suggested that the achieved faradic response of the hemoglobin be due to the promotion properties of carbon nanotube in electron transfer in biomembrane-like polyelectrolyte-surfactant polymer. The entrapped Hb exhibited excellent electrocatalytic activity to reduce hydrogen peroxide. The properties of functional composite film, together with the bioelectrochemical catalytic activity, could make them useful in the development of bioelectronic devices and investigation of protein electrochemistry at functional interface.