Electro-catalysis on H2O2 reduction of electrode capped by nanotubes-polypyrrole composite with hemoglobin integration

Multi-wall carbon nanotubes (MWCNTs) with polypyrrole (Ppy) attachment were selected to play the role of supporter to accommodate hemoglobin (Hb). Metalloprotein-based electrode was prepared on the basis of MWCNTs-Ppy nano-complex with hemoglobin entrapment via conventional wet-coating. Morphology, formation parameters and physio-chemical characteristics of nano-complex with hemoglobin detainment were systematically characterized and analyzed by microscopy, spectrometry and electro-chemistry. Results from measurements and tests implied that the direct electron transferring of Hb-based electrode could be achieved with redox group in Ppy as primary electro-active site and heme sites of Hb in coordination with Ppy as intra-molecular relay. Redox process for heme site of Hb in ligation with Ppy should be attributed to a surface-controlling quasi-reversible electro-chemical reaction with 2 H+ and 2 electron involvement. Such abutting complexation would not impose considerable negative effect on the kinetics of substrate (H2O2) combination and subsequent its transformation. The efficiency of Hb-induced catalysis was limited by the step of substrate diffusion.