Direct electrochemistry and electrocatalysis of hemoglobin on nanostructured gold colloid-silk fibroin modified glassy carbon electrode

In this paper, the electrochemical behavior of Hb assembled on glassy carbon (GC) electrode modified with nanostructured gold colloid-silk fibroin (NGC-SF) was investigated. Electrochemical results show that direct electron transfer of the immobilized Hb occurs as indicated by a couple of quasi-reversible redox peaks with a formal potential of −0.38 V (vs. SCE) in 0.10 M pH 7.0 phosphate buffer. This direct electron transfer process is accompanied by proton exchange and thus the formal potential of Hb changes linearly with solution pH in the range from pH 6.0 to 8.0 with a slope value of −45.2 mV/pH. In addition, the immobilized Hb retains its native catalytic activity to H2O2 without the aid of any electron mediator. This indicates that the presence of NGC-SF can provide a suitable microenvironment for Hb and enhance the direct electron transfer between the hemoglobin (Hb) and electrodes.