A dual-mode PCT electrochemical immunosensor with CuCo₂S₄ bimetallic sulfides as enhancer

A method for the detection of procalcitonin (PCT) with improved accuracy is urgently needed. A dual-mode electrochemical immunosensor with CuCo₂S₄-Au bimetallic sulfides as enhancer for accurate detection of PCT was fabricated in this work. The immunosensor not only displays a heavy square wave voltammetry (SWV) signal due to the electron transfer of Cu²⁺ and Cu⁺ but not the addition of electron mediators. But also presents high electrocatalytic activity towards H₂O₂ redox reactions and enhances the detection sensitivity of the amperometric i-t curve (i-t). The introduction of Au nanoparticles, not only improves the conductivity but also has synergistic effects between Au NPs and CuCo₂S₄, which promote the detection sensitivity by SWV and i-t. To firmly immobilize antibodies, electrolytic gold was used as the matrix for the immunosensor. Based on a CuCo₂S₄-Au dual-signal indicator and electrolytic gold as the matrix, the developed immunosensor for PCT detection in this study demonstrates a wide linear response (0.0001-50 ng/mL) and a low detection limit (SWV: 82.6 fg/mL and i-t: 95.4 fg/mL). Additionally, the fabricated immunosensor exhibited an outstanding analytical approach for PCT and broad application for other biomarkers in clinical diagnosis and treatment.