Electrogenerated Chemiluminescence Behavior Of Cucurbit[n]urils Modified Electrodes

Melon ring（Cucurbit[n]uril,CB[n],n=5-8,10）,also known as cucurbituril,is the fastest-growing large ring in recent years after crown ether,cyclodextrin and calixarene compound.CB[n]s has a negatively charged carbonyl port and a hydrophobic cavity,which can recognize the host and guest with metal ions,small organic molecules,biomolecules,etc,so it is widely used in the environment,food,biology,immunity and other fields.At present,CB[n]s modified electrode has been successfully applied in the field of electrochemistry,but its application in ECL has not been reported.Therefore,this paper studied the ECL behavior of CB[n]s and discussed its potential application in the detection of small organic molecules and metal ions.The main research contents are as follows:1.The ECL behavior of Ru（bpy）₃²⁺on CB[n]s（n=5,6,7,8）modified electrode was studied.Under the neutral condition without co-reactant,the strong anode ECL signal of Ru（bpy）₃²⁺can be generated on the CB[n]s modified electrode.The ECL intensity increases in sequence:CB[5]<CB[6]<CB[7]<CB[8],and the strongest ECL signal was obtained on the modified CB[8]electrode.Based on the spectroscopic and electrochemical results,the ECL mechanism was proposed,and the excited state of Ru（bpy）₃²⁺was confirmed as a luminous body.Lysozyme（Lyz）has a significant inhibitory effect on the ECL of Ru（bpy）₃²⁺on the CB[8]modified electrode,thus enabling its sensitive detection without any labeling.Under the optimal experimental conditions,the sensitive detection of Lyz can be achieved within the range of 1.4×10^-12mg m L^-1to 7.0×10^-10mg m L^-1,and the detection limit was 1.0×10^-13mg m L^-1（3σ）.CB[8]modified electrode has high detection sensitivity and good stability for Lyz.The research results reveal the new application of CB[n]s in the field of ECL sensing,which will promote the analysis and application of macrocyclic molecules.2.A Strong anode ECL of Ru（bpy）₃²⁺can be generated on the CB[8]modified electrode.The ECL mechanism was studied by spectral methods,and the excited state of Ru（bpy）₃²⁺was confirmed as the emitter.Ferrocene can quench the ECL of Ru（bpy）₃²⁺/CB[8]system,on this basis,an ECL aptamer sensor for detecting lysozyme was constructed.Under the best experimental conditions,the linear detection of Lyz was obtained in the range of 1.4×10^-9mg m L^-1to 7.0×10^-7mg m L^-1,and the detection limit was 1.7×10^-10mg m L^-1（3σ）.Experimental results show that this sensor has a better selectivity than direct detection of Lyz.3.Ru（bpy）₃²⁺can generate strong anode ECL signal on CB[6]and CB[8]modified electrodes.The carbonyl groups at the CB[6]and CB[8]ports can form stable complexes with Pb²⁺and Cd²⁺,which further enhances the Ru（bpy）₃²⁺ECL signal on the cucurbit modified electrode,therefore,the effect of Pb²⁺and Cd²⁺on CB[n]s behavior in Ru（bpy）₃²⁺solution was studied.The detection ranges of CB[6]and CB[8]modified electrodes for Pb²⁺was 1.0×10^-6mol L^-1to 5.0×10^-4mol L^-1,and the detection limits were 0.47μM and 0.26μM（3σ）.The detection ranges of CB[6]and CB[8]modified electrodes for Cd²⁺was 1.0×10^-6mol L^-1to 5.0×10^-4mol L^-1,and the detection limits were 0.24μM and 0.27μM（3σ）.Dopamine and resorcinol can quench the ECL of Ru（bpy）₃²⁺/CB[n]system,therefore,the effects of dopamine and resorcinol on CB[n]s behavior in Ru（bpy）₃²⁺solution were studied.The detection range of CB[6]and CB[8]modified electrodes for dopamine was 1.0×10^-7mol L^-1to 5.0×10^-5mol L^-1,the detection limits were 0.03n M and 0.02n M（3σ）.The detection range of CB[6]and CB[8]modified electrodes for resorcinol was 1.0×10^-7mol L^-1to 5.0×10^-5mol L^-1,and the detection limits were 0.03n M（3σ）.