The strategy of nitrite and immunoassay human IgG biosensors based on ZnO@ZIF-8 and ionic liquid composite film

Abstract The strategy of bifunctional electrochemistry platform based on heterogeneous composite ZnO@ZIF-8 and ionic liquid (IL) composite film for nitrite (NO 2 − ) and immunoassay human IgG biosensors was proposed. On the one hand, the electrocatalytic ability of myoglobin (Mb) modified electrode (ZnO@ZIF-8/IL/Mb-CPE) to NO 2 − was studied, and a linear response from 10 to 833 μM with a detection limit of 3.5 μΜ was achieved. On the other, a label-free immunosensor for the determination of human IgG was proposed using ZnO@ZIF-8/IL composite film as immobilization matrix. The differential pulse voltammetry (DPV) response of the developed immunosensor was found to be proportional to logarithm of human IgG concentrations in the two ranges of 0.1-10 and 10–400 ng/mL. The lower detection limit was calculated as 0.03 ng/mL. The excellent properties of ZnO@ZIF-8 were attributed to the synergistic effects of ZnO nanorods with good conductivity, biocompatibility and ZIF-8 with high porosity. Meanwhile, IL not only prevented the aggregation of ZnO@ZIF-8 nanorods, but also displayed excellent ability in facilitating the electron transfer. Both biosensors exhibited good selectivity, reproducibility and stability, indicating ZnO@ZIF-8 composite film could be a promising matrix in electrochemical biosensor design.