A signal-off electrochemical sensing platform based on Fe3S4-Pd and pineal mesoporous bioactive glass for procalcitonin detection

Herein, a sandwich-type electrochemical (EC) immunosensor is proposed based on a special signal-off mode for the sensitive detection of procalcitonin (PCT) by utilizing Fe3S4 loaded with Pd nanoparticles (Fe3S4-Pd) as a signal indicator and matrix and functionalized pineal mesoporous bioactive glass (PBG) as the label for signal amplification. Fe3S4-Pd not only shows excellent electrocatalytic activity for the H2O2 redox reaction but is also firmly immobilized on a magnetic glassy carbon electrode due to its excellent magnetic properties; because of the above features, this immunosensor exhibits excellent sensitivity and stability, respectively. Glutaraldehyde is used as a cross-linking agent to bond the secondary antibodies (Ab(2)) with PBG. It is worth mentioning that the electron transfer rate between the electrolyte and electrode is decreased significantly by PBG-Ab(2); thus, a sensitive variation in the current signal is observed, and a further improvement in the sensitivity of the immunosensor is realized. More importantly, the proposed signal-off sensing system has a wide linear detection range of 500 fg/mL to 50 ng/mL for PCT and a low detection limit of 130 fg/mL, which promotes it as a promising detection method for the sensitive detection of other biomarkers.