Facial Preparation of Cyclometalated Iridium (III) Nanowires as Highly Efficient Electrochemiluminescence Luminophores for Biosensing

In this study, highly efficient ECL luminophores composed of iridium complex-based nanowires (Ir–NCDs) were synthesized via covalently linking bis(2-phenylpyridine)-(4-carboxypropyl-2,2′-bipyridyl) iridium(III) hexafluorophosphate with nitrogen-doped carbon quantum dots (NCDs). The ECL intensity of the nanowires showed a five-fold increase in ECL intensity compared with the iridium complex monomer under the same experimental conditions. A label-free ECL biosensing platform based on Ir–NCDs was established for Salmonella enteritidis (SE) detection. The ECL signal was quenched linearly in the range of 102–108 CFU/mL for SE with a detection limit of 102 CFU/mL. Moreover, the relative standard deviations (RSD) of the stability within and between batches were 0.98% and 3.9%, respectively. In addition, the proposed sensor showed high sensitivity, selectivity and stability towards SE in sheep feces samples with satisfactory results. In summary, the excellent ECL efficiency of Ir–NCDs demonstrates the prospects for Ir(III) complexes in bioanalytical applications.