CoFe-(oxy)hydroxide as a novel electrocatalytic tag in immunosensing for ultra-sensitive detection of procalcitonin...

Nanomaterials play an important role in the fields of electrocatalysis and electrochemical immunosensor. As we all know, electrocatalytic oxygen evolution reaction (OER) can generate intensive current response under alkaline and even neutral conditions, and no by-products are produced. In recent years, OER based on non-noble metal nanocatalysts has become a research focus in the field of new energy, but there are few reports on using it as an electrocatalytic immunosensor label for biomolecule detection. In this study, we successfully synthesized CoFe-(oxy)hydroxide nanosheets through transforming CoFe prussian blue analogue (CoFe PBA). Based on the excellent OER activity of CoFe-(oxy)hydroxide in neutral solution, it was used as a new electrocatalytic marker for capturing procalcitonin (PCT) secondary antibody (Ab₂). Meanwhile, gold nanoparticles (Au NPs) modified glassy carbon electrode (GCE) was utilized as immunosensor platform to immobilize PCT primary antibodies (Ab₁). The linear range of the immunosensor for PCT detection is 0.0005 ∼ 100 ng mL^-1, and the detection limit is 0.33 pg mL^-1. Furthermore, a high recovery was obtained when this proposed method was applied to analysis human serum samples. This work not only provides a new method for clinical analysis of PCT, but also extends the application of electrocatalytic OER.