A microelectrode electrochemical sensing platform based on heteroatoms doped carbon nanotubes arrays with peroxidase-like activity for in-situ detection in live cell.

In this work, we developed a new strategy to fabricate a series of transition metallic nanoparticles (NPs) embedded on B, N co-doped carbon nanotubes (CNTs) arrays modified flexible carbon fiber electrodes (M@BNCNTs/CF, M = Co, Fe, Ni) via facile inkjet printing assisted with chemical vapor deposition using Ionic liquid as solvent of printing ink and heteroatom dopants. Furthermore, Pt NPs via impregnation-thermal reduction process was anchored on the surface of Co@BNCNTs/CF (Pt-Co@BNCNTs/CF), which holds enhanced peroxidase-like activity and could be directly used as freestanding electrode to detect HO, exhibiting a low detection limit of 0.19 μM with wide linear range (0.5 μM-9.4 mM), and high sensitivity (1679 μA cm mM). The excellent sensing performance of Pt-Co@BNCNTs/CF is attributed to the Pt, Co NPs anchored on CNTs with great catalytic activity, and the doping B, N would cause graphitic carbon with more defects to improve its inherent reactivity toward HO. Besides, CNTs arrays with high surface area also enlarge the exposure of active sites. Moreover, the Pt-Co@NBCNTs/CF microelectrode has been successfully applied in monitoring HO secreted from human colonic cancer cells and normal colonic epithelial cells, which could offer crucial data for distinguishing various cell types and identifying cancer cells from normal cells. This work opens a new horizon to fabricate flexible miniaturized sensing device for extracellular analysis and offers an extended strategy to fabricate other metallic NPs embedded in heteroatoms doped CNTs functionalized flexible fiber electrode, by choosing diverse metal ions and ILs as inkjet printing precursors.