Core–shell Fe3O4–Au magnetic nanoparticles based nonenzymatic ultrasensitive electrochemiluminescence immunosensor using quantum dots functionalized graphene sheet as labels

In this paper, a novel, low-cost electrochemiluminescence (ECL) immunosensor using core–shell Fe3O4–Au magnetic nanoparticles (AuMNPs) as the carriers of the primary antibody of carbohydrate antigen 125 (CA125) was designed. Graphene sheet (GS) with property of good conductivity and large surface area was a captivating candidate to amplify ECL signal. We successively synthesized functionalized GS by loading large amounts of quantum dots (QDs) onto the poly (diallyldimethyl-ammonium chloride) (PDDA) coated graphene sheet (P-GS@QDs) via self-assembly electrostatic reactions, which were used to label secondary antibodies. The ECL immunosensors coupled with a microfluidic strategy exhibited a wide detection range (0.005–50 U mL−1) and a low detection limit (1.2 mU mL−1) with the help of an external magnetic field to gather immunosensors. The method was evaluated with clinical serum sample, receiving good correlation with results from commercially available analytical procedure.

Core–shell Fe3O4–Au magnetic nanoparticles and P-GS@QDs were prepared to immobilize Ab1 and Ab2 respectively and combined to fabricate a novel sandwich-type ECL immunosensor for detecting CA125 at low concentration.Figure optionsDownload as PowerPoint slideHighlights
► ECL immunosensor for CA125 based on a microfluidic strategy with a homemade ECL cell was proposed.
► Core–shell Fe3O4–Au magnetic nanoparticles were employed as the carriers of the primary antibodies.
► CdTe quantum dots functionalized graphene sheet were used for signal amplification.