Construction Of Nano Ti₃C₂T_x-based Biosensor For Organophosphates Detection

The enzymatic biosensor has attracted significant attention in the field of detection owing to its multiple advantages?rapid,simple,low cost,etc.?.And the excessive use of organophosphorus pesticides?OPs?results in their residues long-term persistence in environment and thus,severely threats to human beings,animals,plants even environment.Therefore,appropriate measures should be developed to fast and sensitive detection the toxic OPs.And the acetylcholinesterase?AChE?is the most common recognition element in the OPs detection.The key steps in the fabrication of AChE biosensor are to maintain the high activity of AChE and immobilize firmly on the work electrode,thus,the selection of material becomes critical to construct and use of the enzymatic biosensor.In this paper,a new two-dimension material Ti₃C₂T_x with large specific surface area,metal properties,biological compatibility and reduction property was used to construct a series of AChE biosensors based on nano-Ti₃C₂T_x,and applied to the detection of OPs,the main contents were descried as follows:?1?Chitosan?CS?solution was used as dispersing liquid to dissolve Ti₃C₂T_x,the biosensor was fabricated by using Ti₃C₂T_x as nanocarrier to immobilize AChE?labeled AChE/Ti₃C₂T_x/GCE?.The electrochemical behaviors of developed biosensor were studied by cyclic voltammetry?CV?and electrochemical impedance spectroscopy?EIS?.And the parameters?pH,enzyme loading,the concentration of Ti₃C₂T_x,etc.?were optimized.Under optimum conditions,the proposed AChE biosensor was used to detect malathion with a linearity in range of 1×10^-141×10^-8 M and the detection limit was found to be 3×10^-15 M.Due to the excellent biocompatible,film forming ability and no-toxicity of CS and the large surface area and high electrical conductivity of the Ti₃C₂T_x nanosheets,the fabricated AChE biosensor showed acceptable reproducibility,satisfactory stability,and anti-interference ability.Moreover,the analytical performance of the developed biosensor was de monstrated detecting OPs in practical samples and the recovery ranges from 94%to 105%.?2?The Ag@Ti₃C₂T_x nanocomposites were successfully synthesized by using transition metal carbides?Ti₃C₂T_x?as reducing agent and support.Using the Ag@Ti₃C₂T_x nanocomposites modified glassy carbon electrode?GCE?,an AChE biosensor?AChE/Ag@Ti₃C₂T_x/GCE?was fabricated through drop-casting method for electrochemical detection of OPs,via enzymatic inhibition pathway.Due to the synergistic effects between Ag nanoparticles and Ti₃C₂T_x nanosheets not only enlarged the available surface area and electrical conductivity but also facilitated the electron transfer.Under the optimum conditions,the AChE biosensor showed favorable affinity to acetylthiocholine chloride?ATCl?with the Michaelis-Menten constant value 257.67?M and with a linear range from 1×10^-15 to 1×10^-8 M for malathion.Otherwise,the proposed AChE biosensor exhibited satisfactory selectivity,acceptable reproducibility and stability.?3?PB@Ti₃C₂T_x nanocomposites were prepared and acted as nanocarried to develop AChE biosensor?AChE/PB@Ti₃C₂T_x/GCE?,and then studied its performance.PB@Ti₃C₂T_x nanocomposities was used to modify the GCE,not only improved the conductivity of the biosensor,but also provided a good biological compatibility of microenvironment for AChE to maintain its activity.Due to the introduction of PB@Ti₃C₂T_x nanocomposites,the oxidation potential of the AChE was significantly lower,which was good for improving the selectivity and anti-interference ability for its practical application.The AChE/PB@Ti₃C₂T_x/GCE biosensor exhibited good perormance for the determination of malathion with a linearly in range of 1×10^-151×10^-8 M.In addition,the synthesized PB@Ti₃C₂T_x nanocomposite exhibited peroxidase-like activity,which could further expand its research and application in the field of nano-enzyme.