Synthesis Of Novel Ti₃C₂ Composites And Its Application In Electrochemical Biosensors

MXene,a new two-dimensional family of transition metal carbides and/or nitrides,receive extensive attention because they have a layered structure similar to graphene.It has the characteristics of large specific surface area,high electrical conductivity,adjustable components,and controllable thickness.Due to its unique structure and excellent performance,it has shown great potential in energy storage,catalysis,adsorption and biosensors,and this potential has inspired tremendous enthusiasm for research.Ti₃C₂ is a novel two-dimensional material that is most studied in the MXene family.It has great significance in energy storage,catalysis,adsorption and biosensor.However,the research based on Ti₃C₂ nanocomposites is still relatively few,and the biological detection is not widely used in practical applications.Therefore,this paper mainly studies the preparation of two-dimensional Ti₃C₂ nanosheets and its nanocomposites,and different electrochemical biosensors were constructed on many platforms.The specific research contents include the following works:Firstly,Ti₃C₂ nanosheets were prepared and optimized,and Hb/Ti₃C₂-GO/gold foil electrodes were constructed by inkjet printing to detect hydrogen peroxide.Ti₃C₂nanosheets were prepared by selective etching of Ti₃AlC₂ in the mixture of lithium fluoride and hydrochloric acid.The particle size of Ti₃AlC₂ was optimized by ball milling technique.The Ti₃C₂-GO nanocomposites were prepared by a simple method and printed on a conductive substrate.After immobilizing the hemoglobin,the Hb/Ti₃C₂-GO/gold foil electrode was obtained.Electrochemical methods were used to characterize the electrode,and the experimental conditions for the detection of hydrogen peroxide were optimized.The detection of hydrogen peroxide in human serum samples was performed.The experimental results show that the Hb/Ti₃C₂-GO/gold foil electrode can maintain the biological activity of hemoglobin well,and excellent hydrogen peroxide detection results are obtained.A good linear relationship between the response current and the logarithm of hydrogen peroxide concentration with a dynamic range of 2?M to 1 mM,a detection limit of 1.95?M?S/N=3?,high sensitivity,good repeatability,and excellent specific selectivity.Therefore,the method of inkjet printing Ti₃C₂-GO nanocomposites is an excellent preparation method of electrochemical sensors,and has a wide range of applications in biological detection.Secondly,a Ti₃C₂/DNA/Pd/Pt dopamine biosensor was prepared using DNA and Pd/Pt nanoparticle modified two-dimensional Ti₃C₂ nanosheets for the detection of dopamine.DNA is adsorbed on the surface of Ti₃C₂ nanosheets via aromatic hydrophobic groups and induces Pd/Pt nanoparticles to grow in situ on their backbone.The Ti₃C₂/DNA/Pd/Pt nanocomposites were applied on the surface of a glassy carbon electrode to obtain a dopamine biosensor.A variety of electrochemical methods were used to characterize the biosensor.The experimental conditions for the detection of dopamine were optimized,and the detection of dopamine in human serum samples was performed.The results showed that the Ti₃C₂/DNA/Pd/Pt enzyme-free biosensor exhibited excellent electrochemical response to dopamine,showing a good linear relationship between the response current and dopamine concentration.The detection range was 0.2?M to 1 mM,and the detection limit was 30 nM.?S/N=3?,good repeatability,excellent stability,and excellent specific selectivity.Therefore,the prepared enzyme-free dopamine biosensor is an excellent platform for detecting dopamine and provides a new method for biological detection of dopamine.Thirdly,Ti₃C₂-ATP nanocomposites were used as carriers to grow manganese phosphate nanomaterials in situ.A Ti₃C₂/ATP/Mn₃?PO₄?₂ biosensor was constructed to detect the superoxide anion released by cells.ATP is assembled on the surface of Ti₃C₂nanosheets through its aromatic structure.Its negatively charged phosphates adsorb positively charged Mn²⁺,thereby inducing PO₄^3-in situ growth of manganese phosphate nanomaterials on its backbone.The electrochemical behavior of superoxide anion was studied.The superoxide anion was detected by CV,DPV,It and other methods.The experimental conditions for the detection of superoxide anion were optimized.At the same time,cell experiments were carried out to detect the superoxide anion in situ released by the cells.The experimental results show that the Ti₃C₂/ATP/Mn₃?PO₄?₂biomimetic enzyme sensor exhibited excellent electrochemical activity for superoxide anion and showed a good linear relationship between response current and superoxide anion concentration.The detection range was 2.5 nM to 14?M,detection limit as low as0.5 nM?S/N=3?,good stability and repeatability,high sensitivity,and excellent specific selectivity.Therefore,the prepared biomimetic enzyme sensor is an excellent technique for detecting superoxide anion and has a good prospect for practical application.