Layered double hydroxides functionalized with anionic surfactant: Direct electrochemistry and electrocatalysis of hemoglobin

Direct electrochemistry of hemoglobin (Hb), which was immobilized on the glass carbon electrode (GCE) modified with Zn-Al layered double hydroxide (LDH) functionalized with sodium dodecylsulfonate (SDS), was investigated. The resulting electrode (Hb/LDH-SDS/GCE) gave a well-defined redox couple for HbFe(III)/Fe(II) with a formal potential of about -0.34 V (vs. AgCl/Ag) in pH 7.0 buffer. The electron-transfer rate constant was estimated to be 2.6 s(-1). The Hb/LDH-SDS/GCE exhibited a remarkable electrocatalytic activity for the reduction of hydrogen peroxide (H2O2). The low calculated apparent Michaelis-Menten constant (K-M(app)) was 456 mu M. Based on the high catalytic activity of Hb immobilized on LDH-SDS modified electrode to the reduction of H2O2, LDH functionalized with SDS is expected to have widely potential applications for development of new biosensors and biocatalysis. (c) 2008 Elsevier Ltd. All rights reserved.