MXene-based enzymatic sensor for highly sensitive and selective detection of cholesterol.

In this work, the synthesized MXene (Ti3C2Tx) exhibited large specific area, biocompatibility, excellent electronic conductivity, and good dispersion in aqueous phase. The Chit/ChOx/Ti3C2Tx nanocomposite was prepared through the continuous self-assembled process. Its structure is characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Moreover, the biosensor for cholesterol detection was fabricated via a one-step dip-coating method. Chit andTi3C2Tx act as a support matrix to immobilize ChOx enzyme, and also play a role in increasing the electrical conductivity. Meanwhile, the addition of redox mediator (Fe(CN)63-/4-) facilitates the electron transport from the analyte to the modified electrode in the oxidation of cholesterol. The DPV response exhibited an increase in current with increasing cholesterol concentration. Under the optimum conditions, the DPV response of the biosensor indicated a good linear relationship with the concentration of cholesterol ranging from 0.3 to 4.5 nM with a low detection limit of 0.11 nM, and a high sensitivity of 132.66 μA nM-1 cm-2. In addition, with favorable selectivity and stability, the biosensor has been used to detect cholesterol in real samples and the results demonstrate that the biosensor has excellent practicability.