An ultrasensitive cathodic electrochemiluminescence immunoassay for thrombomodulin based on Ru(bpy)₃²⁺ encapsulated by MIL-NH₂-101(Al) nanocomposites

The rapid and reliable determination of thrombomodulin (TM) is of great significance for the diagnosis of disseminated intravascular coagulation, thrombosis and others. This work exhibits an electrochemiluminescent (ECL) sensor, which was prepared using Ru(bpy)32+ encapsulated by MIL-NH2-101(Al) nanocomposites for the sensitive detection of the new-thrombus marker thrombomodulin (TM) for the first time. Specifically, on one hand, with the advantages of high specific surface area, large hollow porous structure and favorable biocompatibility, MIL-NH2-101(Al) could load a large amount of luminescent Ru(bpy)32+ and thereby greatly enhance the ECL signal of the immunosensor. On the other hand, K2S2O8 is used as co-reactant to form a reduction-oxidation ECL system for cathodic ECL detection with strong anti-interference capacity. The experimental results show that the ECL signal intensity of the Ru(bpy)32+@MIL-NH2-101(Al)-based immunosensor decreased with the immunocapturing of TM, exhibiting a linear detection concentration ranging from 1 × 10-5 to 10 μg mL-1 and the limit of detection (LOD) of 8.2 × 10-6 μg mL-1 (S/N = 3). With its ideal stability, selectivity and reproducibility, the proposed ECL immunosensor can provide excellent aid and shows great promise for the detection of TM.