A sandwich electrochemiluminescence immunosensor for highly sensitive detection of alpha fetal protein based on MoS2-PEI-Au nanocomposites and Au@BSA core/shell nanoparticles

Abstract In this work, a novel and universal sandwich-type electrochemiluminescence (ECL) immunosensor was constructed for the sensitive and specific detection of alpha fetal protein (AFP), in which the MoS 2 nanosheets surface was modified using polyethylenimine (PEI) polymer with plentiful amino-groups (MoS 2 -PEI) for warranting their positively charged interface and thereby a large amount of negatively charged gold nanoparticles (AuNPs) were electrostatically adsorbed to form MoS 2 -PEI-Au nanocomposites. Meanwhile, the synthesized Au@BSA nanoparticles were utilized to immobilize molecule recognition probe secondary antibodies (Ab 2 ) and signal probe numerous luminol molecules, respectively. Upon the optimization of assay conditions, the proposed immunosensor displayed wide linear range from 0.0001 ng/mL to 200.0 ng/mL with limit of detection of 1.0 × 10 −5  ng/mL. Moreover, this immunosensor was employed to analyze AFP in real human serum samples with favorable results. The presented immunosensing strategy may provide great potential in the assay of other clinically biomarkers.