An Organ-Like Titanium Carbide Material (MXene) with Multilayer Structure Encapsulating Hemoglobin for a Mediator-Free Biosensor

A novel organ-like MXene-Ti 3 C 2 nanomaterial was successfully prepared by etching Al from Ti 3 AlC 2 in HF at room temperature and then used to immobilise hemoglobin (Hb) to fabricate a mediator-free biosensor with an oxidized surface. MXene-Ti 3 C 2 and its morphology were well characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the physical and electrochemical properties of as-obtained samples were studied by UV-vis diffuse reflectance spectra (DRS) and the electrochemical workstation. Spectroscopic and electrochemical results confirmed that MXene-Ti 3 C 2 exhibited an excellent enzyme immobilization ability with biocompatibility for redox protein, displaying good protein bioactivity and stability. Due to the special structure and properties of MXene-Ti 3 C 2 , the direct electron transfer of Hb is facilitated and the prepared biosensors displayed good performance for the detection of H 2 O 2 with a wide linear range of 0.1–260 μM for H 2 O 2 , as well as an extremely low detection limit of 20 nM (based on a signal-to-noise ratio of 3) for H 2 O 2 . The immobilization of proteins onto the surface of MXene-Ti 3 C 2 is shown to be an efficient method for the development of a new class of sensitive, stable, and promising electrochemical biosensors.