Sensitive and Low-background Electrochemical Immunosensor Employing Glucose Dehydrogenase and 1,10-phenanthroline-5,6-dione

We report a sensitive electrochemical immunosensor with a low electrochemical background level, which results from electrochemical-enzymatic (EN) redox cycling based on mediated electrochemical oxidation of an electro-inactive reductant (glucose) at 0.0 V. The EN redox cycling employs flavin adenine dinucleotide-dependent glucose dehydrogenase and 1,10-phenanthroline-5,6-dione (PD). When PD was compared with five common quinone-based electron mediators, PD enabled the highest signal-to-background ratio, due to a very low electrochemical background level. When EN redox cycling was applied to a sandwich-type immunosensor, parathyroid hormone (PTH) in serum could be detected with a very low detection limit of similar to 0.1 pg/mL.

Automated summary

In this study, a sensitive electrochemical immunosensor with low electrochemical background level was developed using mediated electrochemical oxidation and enzymatic redox cycling. The method showed a high signal-to-background ratio and enabled the detection of parathyroid hormone in serum at a very low limit of 0.1 pg/mL.