Significantly accelerated direct electron-transfer kinetics of hemoglobin in a C(60)-MWCNT nanocomposite film.

The direct electrochemistry of hemoglobin (Hb) was studied in a novel all-carbon nanocomposite film of C(60)-MWCNT (MWCNT=multiple-walled carbon nanotube) and compared with that in bare MWCNT film. The heterogeneous electron-transfer rate constant k(s) of Hb/C(60)-MWCNT was determined to be 0.39 s(-1), which is more than one order of magnitude greater than that of Hb/MWCNT (0.03 s(-1)). The significantly accelerated electron-transfer kinetics are attributed to the mediator role played by C(60), which is finely dispersed on the MWCNT surfaces. The excellent stability of Hb/C(60)-MWCNT was established and its potential application towards the electrocatalytic reduction of O(2) was demonstrated.