Preparation Of Ti₃C₂ Based Nanomaterials And Their Applications In Electrochemiluminescence Sensing

MXene is a class of novel two dimensional transition metal carbides,nitrides or carbonitrides.The general formula for MXene is M_n+1X_nT_x(n=1-3),where M is the transition metal,X is carbon or nitrogen,T is the functional groups terminated on the surface(OH,O,and F),and X is the unit of number of surface groups per ligand.MXene is one of the most concerned two-dimensional nanomaterials at present with metal-like conductivity,good hydrophilicity and excellent mechanical stability.Among them,titanium carbide(Ti₃C₂),as one of the typical MXenes,is the most widely studied multifunctional nanomaterials at present.Due to its high surface area,excellent electrical conductivity,Ti₃C₂ is widely used in energy storage,seawater desalination,catalysis,environment,biomedical and other fields.Based on a comprehensive review of the synthesis,properties and applications of Ti₃C₂ related nanomaterials and electrochemical luminescence mechanism,this paper further focus on the synthesis and application of Ti₃C₂ nanosheet-based composites in electrochemical luminescence.The specific contents are as follows:1.Using graphitized carbon nitride(g-C₃N₄)nanoparticles modified titanium carbide(Ti₃C₂)MXene nanosheets for the construction of electrochemiluminescence(ECL)biosensors,a novel kinase activity assay and inhibitor screening method combining high efficiency recognition and signal amplification was developed.Because of high conductivity,strong catalytic capacity and large surface area,MXene can not only immobilize multiple g-C₃N₄luminescent groups to enhance the luminescent performance,but also have a strong ability to carry electrons and accelerate electron transfer speed,which can effectively alleviate the passivation of g-C₃N₄ under negative sweep potential.In addition,the enriched Ti defect sites on MXene can efficiently combine with the phosphate group of kemptide,which can realize the efficient adsorption of the probe.A sensitive ECL biosensor based on g-C₃N₄-modified MXene probe was constructed to detect protein kinase A(PKA)activity and screen for inhibitors.The detection range for PKA was wide(0.015-40 U m L^-1),and the detection limit was as low as 1.0 m U m L^-1.This study suggests that the proposed ECL biosensor has the potential to be a powerful tool for PKA research,clinical diagnosis,and the development of new targeted drugs.2.TiO₂-Ti₃C₂ nanocomposites with good electrochemical luminescence properties were prepared by a simple one-step method with Ti₃C₂nanosheets as precursors under alkaline conditions by micro-environment control engineering.After characterization by TEM(HETEM),XRD,UV and other characterization methods,it can be concluded that the TiO₂-Ti₃C₂nanocomposites were successfully prepared on the surface of Ti₃C₂ MXene under alkaline oxidation condition.By adjusting different reaction time under alkaline oxidation conditions,TiO₂-Ti₃C₂ nanocomposites with different structures were obtained.The catalytic performance,and the structure-ECL relationship were also investigated.It is found that TiO₂-Ti₃C₂ nanocomposite obtained with reaction time of 3 h has the best ECL luminescence performance and luminous performance.TiO₂-Ti₃C₂nanocomposites with excellent electrical conductivity show great prospect in ECL biosensors and cell imaging.3.Based on the TiO₂-Ti₃C₂ nanocomposite prepared by in-situ oxidation on the surface of Ti₃C₂ MXene,a sensitive and universal ECL glucose biosensor was constructed.In the absence of hydrogen peroxide,hydrogen peroxide produced by glucose oxidase in situ catalyzed by glucose oxidase was used as a co-reaction reagent to decompose hydrogen peroxide under the co-catalysis of TiO₂ and Ti₃C₂,so as to enhance the electrochemical luminescence efficiency of luminol.In addition,the selectivity and anti-interference of the sensor were further improved by glucose oxidase modification.Therefore,based on the surface structure properties of TiO₂-Ti₃C₂,excellent electrical conductivity and catalysis,a highly sensitive and selective detection of glucose can be achieved,with a concentration range of 20 nm-12 m M and a detection limit of 1.2 n M(S/N=3).The method is rapid,simple and reliable,and has been successfully applied to the determination of glucose in sweat,fruit and serum of real samples.