Dual-Ligand Ruthenium Coordination Polymer-Derived Self-Enhanced Electrochemiluminescent Emitters for Sensitive Detection of Procalcitonin

Ru-based electrochemiluminescence (ECL) coordination polymers are widely employed for bioanalysis and medical diagnosis. However, commonly used Ru-based coordination polymers face the limitation of low efficiency due to the long distance between the ECL reagent and the coreactant dispersed in detecting solution. Herein, we report a dual-ligand self-enhanced ECL coordination polymer, composed of tris(4,4′-dicarboxylic acid-2,2′-bipyridyl) ruthenium(II) dichloride (Ru(dcbpy)32+) as ECL reactant ligand and ethylenediamine (EDA) as corresponding coreactant ligand into Zn2+ metal node, termed Zn-Ru-EDA. Zn-Ru-EDA shows excellent ECL performance which is attributed to the effective intramolecular electron transport between the two ligands. Furthermore, the dual-ligand polymer allows an anodic low excitation potential (+1.09 V) luminescence. The shift in the energy level of the highest occupied molecular orbital (HOMO) upward after the synthesis of the Zn-Ru-EDA has resulted in a reduced excitation potential. The low excitation potential reduced biomolecular damage and the destruction of the modified electrodes. The ECL biosensor has been constructed using Zn-Ru-EDA with high ECL efficiency for the ultrasensitive detection of a bacterial infection and sepsis biomarker, procalcitonin (PCT), in the range from 1.00 × 10–6 to 1.00 × 10 ng·mL–1 with outstanding selectivity, and the detection limit was as low as 0.47 fg·mL–1. Collectively, the dual-ligand-based self-enhanced polymer may provide an ideal strategy for high ECL efficiency improvement as well as designing new self-enhanced multiple-ligand-based coordination in sensitive biomolecular detection for early disease diagnostics.