The fabrication of hemoglobin encapsulation into ZIF-67 and its electrochemical property

Hemoglobin (Hb)-based electrodes were fabricated using a Co-based complex with cobalt nitrate hexahydrate and 2-methylimidazole as fundamental elements to accommodate enzymes via the conventional solvothermal method. The binding of redox protein molecules to metal–organic framework-based complexes occurred through a synergistic effect of hydrogen bonding and competitive complexation, resulting in a partially oriented arrangement of metalloprotein molecules with enhanced hydrophilicity. The Hb–Co complex was formed via a typical electrostatic quenching mode with a moderate binding capacity. The native heme site within Hb and the cofactor of the enzyme ligated with ZIF-67 were involved in the electron shuttle process. The former electro-active site displayed favorable electrochemical activity (apparent heterogeneous electron transport rate: 0.1 s –1 ). The inherent configuration of the cofactor in the protein and abnormal electrocatalytic activity of the incorporated protein were considerably maintained. The electrocatalytic efficiency could be affected by both the protein and the Co-based complex. The key step in restraining the electrochemical sensing performance was the H 2 O 2 mass transfer procedure. Graphical abstract The schematic illumination to the preparation procedure of hemoglobin-based electrode on the basis of Co element based MOF material: ZIF-67 as protein carrier via the collaborative effect of the hydrogen bond interaction and the competitive coordination between heme protein and elements in ZIF-67 as well as hemoglobin-induced electro-catalytic H 2 O 2 reduction.