Single-electrode electrochemical system based on tris(1,10-phenanthroline)ruthenium modified carbon nanotube/graphene film electrode for visual electrochemiluminescence analysis

A single-electrode electrochemical system (SEES) has been developed by attaching a plastic sticker with 24 holes onto tris(1,10-phenanthroline)ruthenium (Ru(phen)32+) modified carbon nanotube (CNT)/graphene film electrode for the first time. The Ru(phen)32+ modified CNT/graphene film electrode was fabricated by using CNT/graphene ink with the addition of Ru(phen)32+. The immobilization of Ru(phen)32+ is achieved through the π-π stacking interaction between Ru(phen)32+ and CNT/graphene. The potential difference between the ends of cells in SEES is induced upon applying voltage because of the resistance of the Ru(phen)32+ modified CNT/graphene film electrode, and triggers Ru(phen)32+ electrochemiluminescence (ECL) reaction. By using a smart phone as the detector, visual ECL analysis of multiplex samples was achieved on this newly developed system. Dopamine (DA) can quench triethylamine ECL at Ru(phen)32+ modified CNT/graphene film electrode, enabling visual DA detection. The visual DA detection demonstrates a good linearity in the range of 10−3–10 μM and 50–500 μM. The limit of detection is calculated as 1.9 nM at a signal-to-noise ratio of 3. The ECL system also exhibits excellent long-term stability after storage in the ambient environment for 60 days by comparing the ECL response with its original signal.