In Situ Growing Triethanolamine-Functionalized Metal–Organic Frameworks on Two-Dimensional Carbon Nanosheets for Electrochemiluminescent Immunoassay

A facile strategy for in situ growing triethanolamine (TEOA)-functionalized metal-organic framework (TEOA@MOF) on the two-dimensional graphene oxide (GO) or g-C₃N₄ nanosheets via the self-assembly technique was introduced. In this method, Zn²⁺ was first attached on the carbon nanosheets by electrostatic interaction; then, trimesic acid (H₃btc) acted as the complex agent and TEOA as a base for the deprotonation of H₃btc and a template, which leads to in situ growing the MOF on the carbon nanosheets obtaining a sandwich-like structure. Different types of surface analysis techniques were employed to characterize the GO-TEOA@MOFs and g-C₃N₄-TEOA@MOFs nanomaterials fabricated. The GO-TEOA@MOFs or g-C₃N₄-TEOA@MOFs nanomaterial-modified electrode brings out obviously enhanced electrochemiluminescence (ECL) behaviors due to numerous TEOA in the framework structures. Specifically, both TEOA and GO can serve as the co-reactants for the ECL system of Ru(bpy)₃²⁺ and have the synergic effect of enhancing the signal. Based on the GO-TEOA@MOFs modified electrodes, we developed a sensitive and rapid label-free ECL immunoassay strategy for human copeptin, and the linear range was 5 pg mL^-1 to 500 ng mL^-1 as well as the limit of detection was 360 fg mL^-1. This work exhibits excellent specificity and good stability of the prepared immunosensor in the practical sample determination, demonstrating it can serve as a very promising method for the clinical diagnostics of acute myocardial infarction disease.