# Recent Advances of MXene-Based Electrochemical Immunosensors
## 4 Conclusions and Outlook  
In this review, recent advances in MXenes-based electrochemical immunosensors have been summarized, with a focus on the roles of MXenes as electrode-modified materials and detection antibody labels. Attributed to the excellent properties of MXenes, their application in electrochemical immunosensors have shown encouraging prospects. However, there is still much room for improvement in future research of MXenes-based electrochemical immunosensors to realize the practical applications. (1) Most of the MXenes for preparation of electrochemical immunosensors are synthesized by conventional HF etching. The residual -F group is not only harmful to the environment, but also affects the performance of the sensor. It is urgent to adopt environmentally friendly and efficient synthesis techniques for MXenes, such as alkali etching, electrochemical etching, molten salt etching, etc. [25]. (2) The MXenes used in the preparation of electrochemical immunosensors are  
Figure 6: (**a**) The preparation steps of CuPtRh CNBs/NH\({}_{2}\)–Ti\({}_{3}\)C\({}_{2}\) based Ab\({}_{2}\) label for cTnI detection. Reprinted with permission from Ref. [61]. 2020, American Chemical Society. (**b**) The fabrication steps of sandwich-type electrochemical immunosensor for detection of KIM-1. Reprinted with permission from Ref. [63]. 2021, Elsevier.  
all Ti\({}_{3}\)C\({}_{2}\)T\({}_{x}\) with single performance. In the future, various transition metal carbides such as Nb\({}_{2}\)C [66], Mo\({}_{4}\)VALC\({}_{4}\)[67], and even transition metal nitrides with higher conductivity, such as Ti\({}_{4}\)N\({}_{3}\)[68], can also be applied in electrochemical immunosensors for exploring multiple or synergistic performance. (3) Due to the strong interlayer van der Waals forces, the synthesis of uniform and well-dispersed MXenes remains a great challenge. In the future, interfacial electrochemical self-assembly [69] or other innovative approaches should be utilized to synthesize multi-dimensional MXenes to prevent their restacking and aggregation. (4) Although the multiplex detection electrochemical immunosensor has been fabricated [53], the signals from different analytes cannot be simultaneously displayed on the readout system, and a multiplex detection device has not been developed until now. In the future, using various redox probes [70], it is feasible to design multiple detection platforms that can simultaneously display the signals of different analytes on the readout system. Such platforms can achieve a faster response and further develop the corresponding point-of-care testing (POCT) devices in combination with circuit-board design and smart phones [71; 72]. (5) The current MXene-based electrochemical immunosensors are mainly used for disease diagnosis. In the future, the application scope of MXene-based electrochemical immunosensors can be extended to the environment, agriculture and other fields. In conclusion, the MXenes-based electrochemical immunosensors have promising prospects. The research of MXenes is in the ascendant. It is expected that with the in-depth research on MXenes, high-performance MXene-based electrochemical immunosensors will be developed, thus truly contributing to the production and life of human beings.  
Conceptualization, M.Y. and S.L.; data curation, M.Y. and H.L.; supervision, S.L.; writing--original draft, M.Y.; writing--review and editing, M.Y. and S.L. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China (No. 22175060, 21975067), the Natural Science Foundation of Hunan Province of China (2021)J10014, 2021)J30092) and the Doctoral Research Start-up Fund of Hunan University of Arts and Sciences (21 BSQD43).  
Not applicable.  
The authors declare no conflict of interest.