Construction Of A New Electrochemiluminescence Sensing System Based On Multifunctional Probes Of Ti₃C₂T_X MXene To Detect Polynucleotide Kinase Activity

Electrochemiluminescence（ECL）method has a high sensitivity,which is widely used in sensing systems for sensitive detection of biological substances.In the ECL biosensing system,the core elements are the design of luminophores and probes.Introducing nano materials with excellent properties to improve the analytical performance of ECL is an important means.The transition metal carbide Ti₃C₂T_X MXene（Ti₃C₂T_X）is a new type of two-dimensional nanomaterial,which in addition to the commonality of nanomaterials,also possesses unique catalytic properties,reducibility and abundant Ti active sites.In this work,two types of multifunctional nanoprobes are designed for the detection of polynucleotide kinase（PNK）by taking full advantage of the excellent properties of Ti₃C₂T_X.The constructed ECL biosensors have high sensitivity and specificity.The main research contents are as follows:The good reducibility of Ti₃C₂T_X can generate gold nanoparticles in situ（Ti₃C₂T_X-Au NPs）,and the composite has significant synergistic catalytic performance;using the unique negative charge of Ti₃C₂T_X,the luminophore Ru（bpy）₃²⁺can be immobilized,and the obtained Ru-Ti₃C₂T_X-Au NPs composite as nanoprobes.The probe shortens the electron transport distance between the luminophore and the electrode surface to improve the ECL intensity of the luminophore.Under the condition of no external recognition unit,the 5’end of DNA is phosphorylated by PNK,and it chelates with Ti on the surface of Ru-Ti₃C₂T_X-Au NPs nanoprobe to realize specific recognition and selective detection of PNK.The detection limit was 0.0002 U m L^-1,and the linear range was 0.002-10 U m L^-1.The constructed new method was used for the analysis of PNK in MCF-7 cell lysate,and the recovery rate was 98.0-113.0%.The quantum dot composite luminophore Ti₃C₂ QDs-Au NPs was prepared for the first time.Among them,the excellent electrical conductivity and electrocatalytic properties of Au NPs further enhance the luminescence intensity of Ti₃C₂ QDs;The abundant Ti on the surface of Ti₃C₂ QDs chelates with the DNA phosphorylated by PNK to realize the specific recognition of the target.Combined with the hybridization chain reaction（HCR）signal amplification strategy,the constructed ECL sensing system achieves highly sensitive and specific detection of PNK.The detection limit was as low as 2.7×10^-5 U m L^-1,and the linear range was 0.0001-10 U m L^-1.This strategy was used for the detection of PNK in Hela cell lysate,and satisfactory results were obtained with a recovery rate of 92.1-113.0%,which laid a good foundation for clinical application.