PtAu alloy nanoflowers on 3D porous ionic liquid functionalized graphene-wrapped activated carbon fiber as a flexible microelectrode for near-cell detection of cancer

Recent advances in flexible fiber-based microelectrodes have opened a new horizon for sensitive real-time near-cell and even intracellular measurements. In this work, we develop a new type of hierarchical nanohybrid microelectrode based on three-dimensional (3D) porous graphene-wrapped activated carbon fiber (ACF) via a facile and effective electrodeposition of graphene oxide (GO) nanosheets on ACF using a green ionic liquid (IL) as the electrolyte. This technique enables the simultaneous electrodeposition and electrochemical reduction of GO nanosheets on ACF to form 3D porous IL functionalized electrochemically reduced GO (ERGO)-wrapped ACF (IL-ERGO/ACF). The adsorbed IL molecules on the ERGO surface provide sufficient active sites and act as the template for the in situ electrodeposition of highly dense and well-dispersed bimetal PtAu nanoflowers on the 3D IL-ERGO scaffold. By virtue of the unique array of structural and chemical properties of bimetal PtAu nanocatalysts and 3D porous IL-ERGO on ACF, the resultant PtAu nanoflowers-decorated IL-ERGO/ACF (PtAu/IL-ERGO/ACF) microelectrode demonstrates a variety of excellent sensing performances, including high sensitivity, a wide linear range and good selectivity in the electrochemical detection of a newly emerged cancer biomarker, hydrogen peroxide (H2O2). When used for the real-time tracking of H2O2 secreted from female cancer cells, such as breast cancer cells and gynecological cancer cells, the electrochemical sensor based on the PtAu/IL-ERGO/ACF microelectrode provides important information for distinguishing between different cancer cells and normal cells and for evaluating the therapeutic activity of antitumor drugs towards live cancer cells, which are of great clinical significance for cancer diagnosis and management.