The Catalytic Effect on H2O2 Electro-Reduction of an Electrode Based on MOF Material ZIF-8 as Hemoglobin Supporter via Hydrogen Bond Interaction

2-Methyl imidazole and Zn(NO 3 ) 2 were proposed as raw materials for the hemoglobin (Hb) accommodation matrix ZIF-8, and the encapsulation of Hb molecules onto ZIF-8 was achieved by hydrogen bond interaction and electrostatic attraction. The electrochemical sensing performance of H 2 O 2 for Hb integration into metal–organic framework (MOF) material was analyzed systematically and evaluated quantitatively to identify the key factor in limiting the sensing efficiency. The influence of mutual interactions between Hb and ZIF-8 on the spectroscopic features and sensing efficiency for complexes with Hb incorporation was estimated by multiple techniques to explore the impact of those interactions on the relevant steps involved in the catalysis. The results from experiments revealed that the hydrogen bond between Hb and ZIF-8 led to non-oriented aggregation of enzyme molecules onto the MOF with reduced active surface area and inhibited catalytic activity. The relatively weak interaction between heme protein and MOF material did not result in serious distortion in the structure or chemical nature of Hb entrapment into ZIF-8. The presence of a mutual interaction between Hb and ZIF-8 did not impose a serious negative effect on heterogeneous electron shuttle (28.2–91.2 s −1 ) for the heme site in Hb entrapment into ZIF-8, which was classified into a typical quasi-reversible and thin-film confining mode with the involvement of four electrons and two H + ions. The results showed that hb-induced electrocatalysis was limited by the step of substrate diffusion (1.3 × 10 −3  s −1 ). The Hb-based electrode demonstrated excellent affinity to dissolved H 2 O 2 (Michaelis constant: 28.0 μM) and desirable sensing performance (low detection limitation: 3.7 μM). Graphical Abstract Illustration of the procedure for preparing the electrode based on MOF material (ZIF-8) with hemoglobin accommodation via physical adsorption and electrostatic attraction, which gives rise to non-oriented distribution of hemoglobin attachment onto the surface and inner cavity of ZIF-8.