New luminescent hydrophilic iridium(III) nanoflower at low potential for electrochemiluminescence immunosensing

Screening effective luminophore is always one of the most essential concerns in highly sensitive electrochemiluminescence (ECL) bioanalysis. Here, a new nanoflower-like iridium(III) J-aggregate (T-Ir) was prepared via nonionic surfactant assisted reprecipitation technique, which possessed good reductive-oxidative ECL activity and performed a strong ECL emission around 626 nm at low potential (−1.10 V) in the presence of potassium persulfate. Thus, T-Ir was employed as a luminophore and good biocompatible matrix to load large amounts of capture antibodies (Ab 1 ). Meanwhile, gold nanoparticles capped cuprous oxide nanocubes (Cu 2 [email protected] ) were used as the efficient quencher to label detection antibodies (Ab 2 ). While different dosages of carcinoembryonic antigen (CEA) were introduced via sandwich immunoreaction, the ECL intensity was significantly dropped due to electrochemiluminescence resonance energy transfer from energy donor (T-Ir) to the acceptor (Cu 2 [email protected] ), achieving the highly sensitive detection of CEA. The proposed immunosensor showed a linear concentration range from 1 fg·mL −1 to 80 ng·mL −1 with a low limit of detection of 0.93 fg·mL −1 (S/N = 3). It featured superior stability, selectivity, reproducibility and practicability. With the successful demonstration of hydrophilic iridium(III)-based nanomaterials, sensing strategies for various biomarkers detection in diseases diagnosis will flourish.