Label-Free Electrochemiluminescence Detection of Urinary AD7c-NTP Using Structurally Optimized Iridium(III) Complexes on Boron-Doped Diamond Electrodes

was intercalated into the DNA double-helical structure via electrostatic adsorption, thereby enabling ECL signal detection. Based on the metal-to-ligand charge transfer of iridium complexes at the π-π* energy level and the acceleration of electron transfer from the complexes to the BDD electrode by AuNPs, the established ECL immunosensor exhibited high sensitivity, with a linear range of 0.001-100 ng/mL and an ultralow detection limit of 17.7 fg/mL (S/N = 3). The practicability of the assay was confirmed by the test of AD7c-NTP in human urine, providing valuable information for early screening of AD.