Bioelectrochemistry of hemoglobin immobilized on a sodium alginate-multiwall carbon nanotubes composite film.

This study described the bioelectrochemistry of hemoglobin (Hb) at multiwall carbon nanotubes (MWCNTs) noncovalently functionalized with biopolymers of sodium alginate (SA). The characteristics of Hb/SA-MWCNTs composite film were studied by using FT-IR spectroscopy, UV-vis spectroscopy and electrochemical methods. Hb immobilized on SA-MWCNTs composite film retained its native secondary structure, achieved direct electron transfer with the apparent heterogeneous electron transfer rate constant (k(s)) of (9.54+/-0.883) s(-1) and showed excellent bioelectrocatalytic activity to the reduction of hydrogen peroxide. The amperometric response of the biosensor varied linearly with the H(2)O(2) concentration ranging from 40 to 200 microM, with a detection limit of 16.41x10(-6) M (S/N=3) and the good long-term stability. Finally, we applied this proposed method to investigate the concentration of hydrogen peroxide in real samples.