Construction Of Electrochemiluminescence Sensors Based On The Host-guest Interaction Of Cucurbit[n]uril

Electrochemiluminescene（ECL）is a modern analytical method with high sensitivity.In recent years,a variety of nanomaterials such as graphene,black phosphorous and noble metal nanoclusters have gradually been used to construct electrochemiluminescene sensors.Nevertheless,it is necessary to develop new materials for the construction of electrochemiluminescene sensing systems.Cucurbit[n]uril（n=5-8,10,13-15）is a class of macrocyclic compounds with a hydrophobic cavity and two identical negatively charged carbonyl ports,which can interact with various small molecules and metal ions by host-guest interaction.At present,cucurbit[n]uril has been mostly used in different fields such as molecular recognition,drug carriers and supramolecular polymers.They are also involved in research fields such as electrochemical sensing and fluorescent sensing,but their applications in the field of electrochemiluminescence are rarely reported.Based on this,cucurbit[n]uril is introduced into the field of electrochemiluminescence in this paper,and used to construct a new type of electrochemiluminescence system by its host-guest recognition function,which mainly includes the following three aspects:1.Molybdenum disulfide nanosheets（MoS₂NS）were synthesized by the ultrasonic-assisted liquid phase exfoliation method and characterized by atomic force microscopy,transmission electron microscopy and so on.It can be found that Mo S₂NS has an electrocatalytic effect and can be used as a co-reactant to enhance the ECL emission of Ru（bpy）₃²⁺.The Ru（bpy）₃²⁺ECL signal was inhibited in the presence of ferrocene.Q[7]can encapsulate ferrocene through host-guest interaction,the ECL signal was restored.The strong force of amantadine and Q[7]causes ferrocene to be released from the cavity of Q[7],and the ECL signal decreases again.Based on the variety of ECL signals,an"off-on-off"mode ECL biosensor was constructed to detect amantadine.Under the optimal conditions,amantadine has a good linear relationship with the change of ECL signal in the range of 1 n M to 50 n M with a detection limit of0.27 n M（3σ）.This work focuses on the competition mechanism between Q[7],ferrocene and amantadine,which provides new ideas for the potential application of Q[n]s in the ECL field.2.The ECL behavior of luminol at Q[6]modified electrode was studied.The result indicated that Q[6]can increase luminol ECL signal in a neutral environment.However,the ECL signal decreased sharply when Q[6]forms a stable metal complex with Ag⁺.The variety of ECL signal is linearly related to the concentration of Ag⁺.Thus,Q[6]modified electrode can be used to detect Ag⁺.During the experiment,several influencing factors such as the concentration of luminol,the modification amount of Q[6]suspension and the p H value were optimized.Under the best experimental conditions,the Q[6]modified electrode can sensitively detect Ag⁺in the range of 10 n M to 5μM,and the detection limit is 8.2 n M（3σ）.3.Q[8]can enhance the ECL signal under neutral conditions by studying the ECL performance of luminol on Q[8]modified electrode.Cholesterol oxidase was immobilized on the modified electrode,and the ECL signal decreased obviously.Cholesterol oxidase catalyzes the oxidation of cholesterol to produce hydrogen peroxide.The combination of hydrogen peroxide and luminol can obtain a stronger ECL signal.Based on this,an ECL biosensor was constructed to detect cholesterol indirectly.The concentration of luminol,the p H value,the modification amount of Q[8]and the potential scanning rate were optimized.Under the best experimental parameters,the sensor can linearly detect cholesterol in the range of 0.1μM to 0.1m M,with a detection limit 0.038μM（3σ）.This work reveals the application potential of Q[8]in the construction of ECL biosensors.