Research Of Electrochemical Biosensor Based On Ti₃C₂T_x Modified Glassy Carbon Electrode

The development of high-performance electrochemical sensors with high sensitivity,low detection limits and a wide detection range is of great importance for the detection of biological small molecules.Glassy carbon electrodes have been widely used as working electrodes for electrochemical sensors because of their good electrical conductivity,chemical stability,inability of gases to pass through the electrode,high purity,and easy surface regeneration.As the original electrode has no molecular recognition ability and low response signal,it is difficult to sensitively detect small biological molecules.The above deficiencies of bare glassy carbon electrodes can be effectively improved by modifying electrodes with nanomaterials,and it is particularly important to design and select nanomaterials for modified electrodes.In this paper,two electrochemical sensors were constructed for the high-performance detection of ascorbic acid and dopamine by exploiting the advantages of large specific surface area,excellent electrical conductivity,good biocompatibility and more modification potential of Ti₃C₂T_x ,and further modification of Ti₃C₂T_x by different metal nanoparticles.（1）Ti₃C₂T_x nanomaterials were prepared by selective etching,and Ag/Pt/Ti₃C₂T_x materials for electrode modification were prepared by growing Ag/Pt nanoparticles on Ti₃C₂T_x by sodium borohydride reduction.Due to the layered Ti₃C₂T_x ,a larger specific surface area is provided,enhancing the adsorption of ascorbic acid at the working electrode;a smaller electron transfer resistance,improving the electron transfer capacity;and Ag/Pt/Ti₃C₂T_x has a large electrochemically active area,allowing more active sites for electrochemical reactions to be obtained.Using the advantages of the above three points,the electrochemical reaction rate is improved,which in turn enhances the sensitive characteristics of the sensor and constructs an ascorbic acid electrochemical sensor with excellent performance.The electrochemical ascorbic acid sensor based on Ag/Pt/Ti₃C₂T_x modified glassy carbon electrode has a wider linear range and lower detection limit than those previously reported for other modified materials.The sensitivity was 6.78μA/m M and the lower detection limit was 4.78μM（S/N=3）over a linear detection range of 200～9800μM.（2）Au/Ti₃C₂T_x materials for electrode modification were prepared by growing Au nanoparticles on Ti₃C₂T_x using selective etching and sodium borohydride reduction.The effect of Ti₃C₂T_x and Au/Ti₃C₂T_x modified glassy carbon electrodes on the performance of the sensor was investigated.The Ti₃C₂T_x modified glassy carbon electrode enabled the sensor to detect dopamine（response current value of3.84μA for 10μM dopamine）,and the modification of Au nanoparticles further enhanced the sensor’s ability to detect dopamine,with a response current value of4.76μA for 10μM dopamine.The current value of 4.76μA was 1.24 times higher than that of Ti₃C₂T_x /GCE.The electrochemical sensor based on Au/Ti₃C₂T_x /GCE working electrode has the best sensing performance for the following reasons:Ti₃C₂T_x has a large specific surface area and excellent electrical conductivity,which improves the electron transfer capacity and enhances the electrocatalytic activity of the electrode towards dopamine;the introduction of Au nanoparticles further improves the electron transfer capacity and electrocatalytic activity due to the excellent electrocatalytic activity of gold nanoparticles ability and electrocatalytic activity;the synergistic interaction between Au nanoparticles and Ti₃C₂T_x obtained a larger electrochemically active area,and the larger electrochemically active area could provide more active sites,increase the interaction between the working electrode and dopamine,and promote the rapid electrochemical reaction.The dopamine electrochemical sensor based on the Au/Ti₃C₂T_x /GCE working electrode has a high sensitivity of 0.29μA/μM and a low detection limit of 0.267μM in the range of 0.5μM-50μM.In summary,two different Ti₃C₂T_x-based nanocomposites,Ag/Pt/Ti₃C₂T_x and Au/Ti₃C₂T_x ,were prepared and used for the modification of a glassy carbon working electrode to construct an electrochemical biosensor for the accurate and efficient detection of ascorbic acid and dopamine,which has excellent sensitivity performance and has good prospects for application.