Highly sensitive luminol electrochemiluminescence immunosensor based on platinum-gold alloy hybrid functionalized zinc oxide nanocomposites for catalytic amplification

Abstract

A highly sensitive sandwiched luminol electrochemiluminescence (ECL) immunosensor has been constructed based on the double catalysis effect and multiamplification strategy of platinum-gold alloy hybrid functionalized zinc oxide nanocomposites (Pt-Au@ZnONPs). First, the improved surface area and excellent biocompatibility of Pt-Au@ZnONPs were used for binding the secondary antibody (Ab2) and glucose oxidase (GOD) to obtain the novel bioconjugate Pt-Au@ZnONPs-GOD-Ab2. Pt-Au@ZnONPs and the loaded GOD amplified luminol ECL signals and promoted the luminol ECL response by efficiently catalyzing glucose to produce hydrogen peroxide (H2O2) in situ as a coreactant of luminol. Then, Pt-Au@ZnONPs catalyzed H2O2 to generate various reactive oxygen species (ROSs) that accelerated the ECL reaction of luminol, thus enhanced the ECL intensity of luminol and improved the sensitivity of the immunosensor. Second, gold nanoparticles decorated reduced graphene sheets (AuNPs@GS) with large specific surface area, good biocompatibility, high conductivity, and high catalytic activity were prepared and used as substrate of the immunosensor to capture the primary antibody (Ab1). Experimental results demonstrated that the proposed ECL immunosensor showed a sensitive response for the detection of α-1-fetoprotein (AFP) from 0.1 pg mL−1 to 200 ng mL−1 with detection limit of 0.03 pg mL−1 (S/N = 3). The as-proposed luminol ECL immunosensor has excellent sensitivity, stability, and specificity, which makes it very promising for clinical applications.