Amperometric third-generation hydrogen peroxide biosensor incorporating multiwall carbon nanotubes and hemoglobin

An amperometric third-generation hydrogen peroxide biosensor was designed by immobilizing hemoglobin (Hb) on a glassy carbon electrode modified with multiwall carbon nanotubes, (MWNT). The direct electron transfer of the Hb immobilized on the MWNT-modified electrode was observed. The formal potential of the immobilized Hb was -0.241 V versus Ag/AgCl (3 M NaCl) and the heterogeneous electron transfer rate constant was 0.58 s(-1) in a 0.20 M acetate buffer solution (pH 5.4). The immobilized Hb exhibited excellent electrocatalytic activity to reduce hydrogen peroxide in the absence and presence of oxygen, which facilitated designing an amperometric third-generation biosensor for hydrogen peroxide. In the presence of oxygen, the response to hydrogen peroxide of the designed biosensor at a potential of -0.35 V was linear in the concentration range from 6.0 x 10(-6) to 6.0 x 10(-3) M, and the detection limit was 1.2 x 10(-6) M. The relative standard deviation was 2.4% for nine successive assays at 1.0 x 10(-5) M hydrogen peroxide. The designed biosensor was applied to the determination of hydrogen peroxide in pharmaceutical injections with high sensitivity and rapid response. (c) 2005 Elsevier B.V. All rights reserved.