Highly Stable Mesoporous Luminescence-Functionalized MOF with Excellent Electrochemiluminescence Property for Ultrasensitive Immunosensor Construction

In this work, a novel mesoporous luminescence-functionalized metal–organic framework (Ru–PCN-777) with high stability and excellent electrochemiluminescence (ECL) performance was synthesized by immobilizing Ru­(bpy)₂(mcpbpy)²⁺ on the Zr₆ cluster of PCN-777 via a strong coordination bond between Zr⁴⁺ and −COO^–. Consequently, the Ru­(bpy)₂(mcpbpy)²⁺ could not only cover the surface of PCN-777 but also graft into the interior of PCN-777, which greatly increased the loading amount of Ru­(bpy)₂(mcpbpy)²⁺ and effectively prevented the leaching of the Ru­(bpy)₂(mcpbpy)²⁺ resulting in a stable and high ECL response. Considering the above merits, we utilized the mesoporous Ru–PCN-777 to construct an ECL immunosensor to detect mucin 1 (MUC1) based on proximity-induced intramolecular DNA strand displacement (PiDSD). The ECL signal was further enhanced by the enzyme-assisted DNA recycling amplification strategy. As expected, the immunosensor had excellent sensitivity, specificity, and responded wide linearly to the concentration of MUC1 from 100 fg/mL to 100 ng/mL with a low detection limit of 33.3 fg/mL (S/N = 3). It is the first time that mesoporous Zr–MOF was introduced into ECL system to assay biomolecules, which might expand the application of mesoporous metal–organic frameworks (MOFs) in bioanalysis. This work indicates that the use of highly stable mesoporous luminescence-functionalized MOFs to enhance the ECL intensity and stability is a feasible strategy for designing and constructing high-performance ECL materials, and therefore may shed light on new ways to develop highly sensitive and selective ECL sensors.