Immobilizing haemoglobin on gold/graphene–chitosan nanocomposite as efficient hydrogen peroxide biosensor

A method is reported for the preparation of novel electrode by layer-by-layer assembly of haemoglobin (Hb), gold (Au) nanoparticles, chitosan (CS) and graphene (GR) onto glassy carbon electrode (GCE). The Au/GR–CS substrate shows an obvious promotion for the direct electron transfer between Hb and GCE. The surface concentration (Г*) of Hb on the as-modified electrode can be as high as 4.33 × 10−9 mol/cm2, which is 228 times higher than the theoretical value for Hb monolayer on bare GCE. The Au/GR–CS/GCE shows good electrocatalytic performance for the reduction of hydrogen peroxide within a linear range from 2 to 935 μM, a low detection limit of 0.35 μM (S/N = 3) and high sensitivity of 347.1 mA cm−2 M−1. The Au/GR–CS nanocomposite demonstrates as a versatile matrix for immobilizing redox protein to realize direct electrochemistry and hence prepare efficient and robust biosensor.