An ultrasensitive luminol cathodic electrochemiluminescence immunosensor based on glucose oxidase and nanocomposites: Graphene–carbon nanotubes and gold-platinum alloy

• Chi-GR-CNTs composite exhibited strong cathodic ECL behavior of luminol under −0.1 to 0.4 V.
• The nano-AuPt was adopted to further enhance ECL signal and mobilize more proteins.
• Glucose oxidase was used to block non-specific sites for generating H2O2 in situ.
• The prepared immunosensor displayed an excellent sensitivity.

In the present study, a novel and ultrasensitive electrochemiluminescence (ECL) immunosensor based on luminol cathodic ECL was fabricated by using Au nanoparticles and Pt nanoparticles (nano-AuPt) electrodeposited on graphene–carbon nanotubes nanocomposite as platform for the detection of carcinoembryonic antigen (CEA). For this introduced immunosensor, graphene (GR) and single wall carbon nanotubes (CNTs) dispersed in chitosan (Chi-GR-CNTs) were firstly decorated on the bare gold electrode (GE) surface. Then nano-AuPt were electrodeposited (DpAu-Pt) on the Chi-GR-CNTs modified electrode. Subsequently, glucose oxidase (GOD) was employed to block the non-specific sites of electrode surface. When glucose was present in the working buffer solution, GOD immediately catalyzed the oxidation of glucose to in situ generate hydrogen peroxide (H2O2), which could subsequently promote the oxidation of luminol with an amplified cathodic ECL signal. The proposed immunosensor was performed at low potential (−0.1 to 0.4 V) and low concentration of luminol. The CEA was determined in the range of 0.1 pg mL−1 to 40 ng mL−1 with a limit of detection down to 0.03 pg mL−1 (S N−1 = 3). Moreover, with excellent sensitivity, selectivity, stability and simplicity, the as-proposed luminol-based ECL immunosensor provided great potential in clinical applications.

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