Single-layer graphene as a transparent electrode for electrogenerated chemiluminescence biosensing

Abstract

This study investigates graphene grown by chemical vapor deposition (CVD) as an optically transparent electrode for electrogenerated chemiluminescence (ECL) analytical applications. The ECL performance on CVD graphene with a Ru(bpy)32+/tripropylamine (TPrA) system was investigated and compared with that of a typical carbon-based electrode, glassy carbon (GC), and the conventional transparent electrode, indium tin oxide (ITO), in front-facing and transmission cell ECL collecting geometries. The graphene electrodes exhibited a lower oxidation potential for TPrA than ITO and thus a higher ECL intensity, in which similar electrochemical properties to GC were observed. The voltammetric and corresponding ECL responses on graphene were observed at a slightly more positive potential compared to GC due to the internal resistance of graphene. However, the graphene electrode showed higher ECL intensity than GC by detecting ECL from the backside of the electrode owing to its high transparency. Furthermore, a bead-based heterogeneous ECL immunoassay for carcinoembryonic antigen, a type of tumor marker, was successfully demonstrated using graphene electrodes. Optically transparent graphene films are promising electrodes for developing POC devices based on ECL analytical technologies because they are composed of a sustainable material (carbon atoms), making them suitable for use as disposable electrodes, and their surface can be easily modified with biomolecules.