Nitrogen and sulfur co-doping strategy to trigger the peroxidase-like and electrochemical activity of Ti3C2 nanosheets for sensitive uric acid detection

The development of functional nanomaterials based on the unique structure and morphology of MXene for biosensing has aroused great interest. In this work, using thiourea as the doping source, a new structure composed of nitrogen and sulfur co-doped on the surface of Ti3C2 nanosheets was synthesized through a simple one-step synthesis method. Fortunately, the obtained nitrogen and sulfur co-doped Ti3C2 nanosheets (NS-Ti3C2 NSs) showed excellent peroxidase-like activity and electrochemical activity. The catalytic mechanism of modified Ti3C2 nanosheets was explored. It is revealed that the catalytic mechanism of NS-Ti3C2 NSs is composed of two important parts: the dissociation and adsorption of H2O2 and the protonation of TMB. In addition, the fabricated NS-Ti3C2 NSs-based electrochemical biosensor is superior to the counterpart from Ti3C2 nanosheets, indicating that the doping of nitrogen and sulfur elements provides more active sites and promotes electron transport efficiency. Combining the unique advantages of colorimetry and electrochemical technology, we have developed a fast, accurate, intuitive and efficient UA detection method for uric acid in the range of 2 μM-400 μM with a detection limit (LOD) of 0.19 μM. The established sensing platform in this study prove the possibility of the doping method for the development of MXene-based biosensors with high sensitivity and high performance, and pave the way for the future development of biosensors for biomedical fields.