A novel nitrite biosensor based on the direct electrochemistry of hemoglobin immobilized on MXene-Ti3C2

Two-dimensional layered Ti3C2-based material (MXene-Ti3C2), which is a new graphene-like nanomaterials, has been synthesized and then used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of MXene-Ti3C2 were characterized by scanning electron microscopy and X-ray diffraction. Spectroscopic and electrochemical results revealed that MXene-Ti3C2 is an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Due to the large surface area and the high conductivity of MXene-Ti3C2, the direct electron transfer of Hb is facilitated and the prepared biosensors displayed good performance for the detection of nitrite with a wide linear range of 0.5–11800 μM, as well as an extremely low detection limit of 0.12 μM. This work suggests that MXene-Ti3C2 is a potential candidate for efficient enzyme immobilization and promising in environmental analysis.