Functionalized graphene fiber modified by dual nanoenzyme: Towards high-performance flexible nanohybrid microelectrode for electrochemical sensing in live cancer cells

The development of flexible miniaturized electrochemical sensors based on functionalized microelectrode systems has gained numerous attentions for their promising application in potable, implantable and wearable medical devices. In this work, we report a facile strategy to construct a new type of high-performance microelectrode based on wet-spinning graphene fiber (GF) functionalized by dual nanoenzyme composed of ultrafine Au nanoparticles (Au-NPs) wrapped flower-like MnO2 nanowires (MnO2-NWs) assembly (MnO2-NWs@Au-NPs), and explore its practical application in electrochemical detection of biomarker hydrogen peroxide (H2O2) released from live cancer cells. Benefiting from the advantage of the unique hierarchical nanohybrid structure and dual nanoenzyme activity, the resultant MnO2-NWs@Au-NPs modified GF microelectrode shows superior catalytic activity towards the electrochemical redox reaction of H2O2. When used in amperometric detection of H2O2, the nanohybrid microelectrode exhibits high sensitivity and selectivity as well as good mechanical stability and biocompatibility, and can be used in real-time in situ detection of H2O2 released from human breast cancer cells, which contributes to the development of high-performance hierarchically nanostructured microelectrode in electrochemical sensing system for sensitive detection of various targets in biological samples.