Validated electrochemical immunosensor for ultra-sensitive procalcitonin detection: Carbon electrode modified with gold nanoparticles functionalized sulfur doped MXene as sensor platform and carboxylated graphitic carbon nitride as signal amplification

Abstract

Septicemia, also known as sepsis, refers to a systemic inflammatory response syndrome and becomes thedominant reason of mortality for seriously diseases. Procalcitonin (PCT), the peptide precursor of the hormones,is a key biomarker of septicemia in the diagnosis and detection of bacterial inflammation. In this study, an ultra-sensitive sandwich type electrochemical immunosensor for PCT detection was constructed. Firstly, delaminatedsulfur-doped MXene (d-S-Ti3C2TXMXene) modified glassy carbon electrode (GCE) including gold nanoparticles(AuNPs) was utilized as immunosensor platform to increase the amount of PCT antibody1 (Ab1). After that,carboxylated graphitic carbon nitride (c-g-C3N4) was used to label PCT Ab2as signal amplification. The structureof electrochemical immunosensor was highlighted by x-ray diffraction (XRD) method, scanning electron mi-croscope (SEM), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), fouriertransform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry(CV). Herein, c-g-C3N4not only has excellent catalytic activity toward H2O2for signal amplification, but also canbe directly utilized as redox probe. The analytical results have revealed that 0.01 - 1.0 pg mL-1and 2.0 fg mL-1were found as linearity range and limit of detection (LOD). Furthermore, the validated electrochemical im-munosensor was examined in terms of stability, repeatability, reproducibility and reusability. Finally, the im-munosensor was applied to plasma samples having high recovery