Ruthenium complex doped metal-organic nanoplate with high electrochemiluminescent intensity and stability for ultrasensitive assay of mucin 1

Abstract

In this study, a novel Ru(bpy)2(dcbpy)-doped two-dimensional (2D) metal-organic framework (MOF) nanoplate (Ru@Zr12-BPDC, BPDC = 4,4′-biphenyldicarboxylate, bpy = 2,2'-bipyridine, H2dcbpy = 2,2'-bipyridine-5,5'-dicarboxylic acid) with outstanding ECL performance was synthesized via a mixed ligand strategy. The matching lengths between Ru(bpy)2(dcbpy) and BPDC ligands allowed the Ru(bpy)2(dcbpy) to bridge two Zr12 clusters of Ru@Zr12-BPDC nanoplate through strong coordination bonds, which not only resulted in the increase of the immobilization amount of Ru(bpy)2(dcbpy), but also prevented the leakage of the Ru(bpy)2(dcbpy) effectively. Furthermore, the high porosity and ultrathin nature of 2D Ru@Zr12-BPDC nanoplate not only allowed the electrochemical activation of the internal and external Ru(bpy)2(dcbpy), but also greatly shortened the diffusion paths of the ions, electrons, coreactant (tripropylamine, TPrA) and coreactant intermediates (TPrA• and TPrA•+), which made more interior Ru(bpy)2(dcbpy) could be excited and thus led to the increasing utilization ratio of the luminophores. Because of the above merits, the Ru@Zr12-BPDC nanoplate exhibited high and stable ECL emission, and thus was employed to construct an aptasensor for ultrasensitive detection of mucin 1 (MUC1). To further enhance the sensitivity of the proposed aptasensor and amplify signal, the target MUC1 was converted into the H1-H2 duplex with the assistance of H1, H2 and MUC1-catalyzed hairpin assembly (CHA). As expected, the proposed aptasensor exhibited remarkable stability, excellent sensitivity, high sensitivity and displayed a wide liner range from 1 fg/mL to 10 ng/mL with a low detection limit of 0.14 fg/mL. To our knowledge, it is the first example of the construction of an ECL biosensor based on ruthenium complex doped 2D MOF nanoplates. This study demonstrated that the use of ruthenium complex doped MOF nanoplates to increase the ECL stability and intensity is an efficient strategy for the construction of highly stable and sensitive ECL biosensors, and therefore may extend the applications of 2D MOF nanoplates in ECL and bioanalysis fields.