A label-free electrochemical immnunosensor based on signal magnification of oxygen reduction reaction catalyzed by uniform PtCo nanodendrites for highly sensitive detection of carbohydrate antigen 15-3.

Developing a highly sensitive immunoassay for tumor biomarkers is particularly important in bioanalysis and early disease diagnosis. In this work, a simple one-pot solvothermal method was developed for controllable synthesis of well-dispersed PtCo alloyed nanodendrites (PtCo NDs) by using l-carnosine as the co-structure-directing agent. The PtCo NDs had a large specific surface area and provided abundant active sites available for electrocatalytic oxygen reduction reaction (ORR). Based on the highly enhanced currents of the ORR, a novel label-free electrochemical immunosensor was fabricated for highly sensitive assay of carbohydrate antigen 15-3 (CA15-3). The sensor showed a wide linear range of 0.1-200 U mL-1 and a low limit of detection (LOD) down to 0.0114 U mL-1 (S/N = 3), in turn exploring its application to diluted human serum samples with satisfactory results. This study provides a feasible platform for monitoring other tumor markers in clinical diagnosis.