Self-referenced ratiometric electrochemical biosensor based on covalent organic framework assembled MXene for stain-resistance and sensitive sensing of dopamine.

Dopamine (DA) is not only an important neurotransmitter involving in the regulation of life activities, but also a typical biomarker of neurodegenerative diseases. Accurate detection of DA content is of great significance for early diagnosis and treatment of related illness. Herein, a ratio electrochemical sensing platform was constructed based on covalent organic framework (COF) assembled MXene composite nanomaterials for sensitive, selective and accurate detection of DA. β-ketoenamine COF with high electrochemical activity can export a stable electrochemical signal during the sensing process, which provides the necessary conditions for the construction of ratio electrochemical biosensor. MXene, an emerging material with rich functional groups, as a carrier for in-situ growth of COF, effectively improves the material conductivity, and significantly amplifies the reference signal of COF and response signal of DA, simultaneously. It is the hydrogen bonds and van der Waals force between COF and the target molecule that achieve the selective response of the modified material to DA. Due to the synergistic effect between COF and MXene, the sensing platform (TFAQ COF@MXene/GCE) exhibited an excellent analytical performance towards DA with a wide linear range (0.05-800 μM) and low detection limit (0.0061 μM) as well as good stain-resistance and reproducibility and achieved precise analysis of DA in drug injection and human serum. This work provides a new and effective strategy for constructing COFs-based electrochemical sensors with self-calibration, strain-resistance and significant signal amplification.