A hybrid immunosensor based on gold nanodendrimer-decorated MoS2 nanoflowers for label-free detection of alpha-fetoprotein

Abstract

This study presents a novel label-free immunosensor for the ultrasensitive detection of alpha-fetoprotein (AFP), used as a specific biomarker in early detection of hepatocellular carcinoma (HCC), based on the uniform decoration of hybrid nanostructures comprising molybdenum disulfide nanoflowers (MoS₂NFs) and chiral gold nanodendrimers (AuNDs). In the proposed design, MoS₂NFs in a metallic phase (1T), which has a large electroactive surface area and abundant active sites, were uniformly decorated with chiral AuNDs through synergistic interactions on screen-printed carbon electrodes (SPCEs). Monoclonal anti-AFP antibodies (mAb) were subsequently immobilized via a carbodiimide-mediated coupling reaction to generate a highly sensitive and specific capture interface (AuNDs@1T-MoS₂NFs/mAb/SPCE) towards the AFP. The detection mechanism relies on the impediment of electron transfer caused by the formation of an AFP–antibody immunocomplex on the electrode surface, which reduces the redox current of [Fe(CN)₆]^3−/4− used as an electrochemical probe. Differential pulse voltammetry (DPV) measurements revealed strong and well-defined redox peaks from the AuNDs@1T-MoS₂NFs/mAb interface, which were progressively suppressed with increasing AFP concentrations, indicating the successful formation of the immunocomplex layer on the sensing platform. The developed immunosensor exhibited an impressively low detection limit of 12.4 fg mL⁻¹ and a wide dynamic linearity ranging from 20 fg mL⁻¹ to 1 ng mL⁻¹. The practical applicability of the developed immunosensor was demonstrated through the selective detection of the AFP in human serum samples, which were promising results for the early detection of HCC.