Green and controllable synthesis of multi-heteroatoms co-doped graphene fiber as flexible and biocompatible microelectrode for in situ electrochemical detection of biological samples

In this work, we report a green and facile strategy to synthesize a new type of multi-heteroatoms co-doped graphene fiber (GF) using graphene nanosheets as the building block and eco-friendly ionic liquid (IL) molecules as the heteroatoms-containing precursor, where the type of heteroatoms doped in graphene can be adjusted by choosing different IL molecules. Among different multi-heteroatoms co-doped GF microelectrodes, N, B co-doped GF (NBGF) possesses the largest specific surface area and lowest charge transfer resistance, which gives rise to an improvement on the electrocatalytic activity towards H2O2 reduction. When used in amperometric detection of H2O2, NBGF microelectrode exhibits good sensing performance as well as unique flexibility and biocompatibility, these enable it to be used for real-time tracking H2O2 released from different colorectal cancer cells, which provide the possibility to distinguish different types of cancer cells and evaluate the efficacy of chemotherapy drugs by electrochemical sensing system. Moreover, the proposed NBGF microelectrode has been applied in in situ sensitive detection of H2O2 in tumor tissue from female Balb/c mice. Therefore, this study presents a new strategy for the rational design of functionalized GF based microelectrode with potential widespread use in implantable sensor devices for clinic application.