Ultrasensitive Electrochemiluminescence Immunosensor of Procalcitonin Based on Synergistic Enhancement by Hf-MOF/g-C₃N₄ via Integration of Dual Luminophores, a Coreactant Accelerator, and Energy Transfer

A synergistic enhanced electrochemiluminescence (ECL) method was proposed. Synergistic enhancement was achieved by incorporating a coreactant accelerator through energy transfer between dual luminophores, g-C₃N₄ and Hf-MOF. In addition, a sandwich-type ECL immunosensor was developed for the ultrasensitive detection of procalcitonin (PCT), in which the primary antibody was labeled with the g-C₃N₄@Au nanoparticles that immobilized on an electrode surface and the secondary antibody was labeled with Hf-MOF. Apart from a luminophore, Hf-MOF also acted as a coreactant accelerator, catalyzing the generation of sulfate radical anions (SO₄^•-) by reactive oxygen and potassium persulfate. Furthermore, Hf-MOF acted as an acceptor of energy transfer of the luminophore intermediate g-C₃N₄, which greatly enhances the ECL signal. The ECL intensities of Hf-MOF/g-C₃N₄/S₂O₈^2- were 2.3 and 4.4 times higher than the ECL intensities of the Hf-MOF/S₂O₈^2- and g-C₃N₄/S₂O₈^2- systems, respectively. The response signal of the ECL immunosensor showed a good linear relationship with 10 fg/mL-100 ng/mL PCT, showing a detection limit of 3.3 fg/mL, which was much lower than of the reported method. The proposed method is feasible for the rapid identification and detection of systemic bacterial infections and for the prevention of abuse of antibiotics.