Dual-signal sandwich-type electrochemical immunoassay of galectin-3 using methylene blue and gold nanoparticles biolabels

The rapid and sensitive detection of heart failure biomarker galectin-3 (Gal-3) is of great value in the prevention, diagnosis, treatment, and prognosis-evaluation of heart failure. Here, a high-performance dual-signal sandwich-type electrochemical immunosensor for Gal-3 was constructed by the covalent immobilization of the first antibody on electroreduced carboxyl graphene and the adsorption immobilization of the second antibody in aminated mesoporous silica nanoparticles labeled with methylene blue (MB) and gold nanoparticles (AuNPs). The relevant electrodes and materials were characterized by electrochemistry, quartz crystal microbalance, scanning electron microscopy and energy dispersive spectroscopy. Under optimized conditions, the MB-based in-situ microdroplet voltammetry showed a linear detection range (LDR) of Gal-3 from 50 fg mL−1 to 500 ng mL−1, with a limit of detection (LOD, S/N = 3) of 2.0 fg mL−1; and the AuNPs-based in-situ microdroplet anodic stripping voltammetry showed an LDR of Gal-3 from 0.5 fg mL−1 to 500 ng mL−1, with a LOD (S/N = 3) of 0.17 fg mL−1. The detection of clinical serum samples by our method returned satisfactory results. This research may help the high-sensitivity voltammetric detection of both noble metal nanomaterials and other electroactive biolabels for wider bioanalysis applications.