Preparation Of Novel Electrochemiluminescence Sensors Based On MOFs Composites And Its Application In Marine Pollutants Detection

The marine pollution caused by human activities are becoming more and more serious.Pollutants entering the ocean will eventually cause irreversible damage to the health of human and other species.Electrochemiluminescence（ECL）sensor integrates the unique analytical advantages of electrochemical analysis and chemiluminescence analysis technology.It does not need to apply external light source in the whole ECL process,which makes up for the disadvantage of large background signal in single spectroscopy analysis.ECL sensor with the advantages of high sensitivity,controllable time and space,simple operation,wide dynamic range and strong stability has been widely used in immunoassay,environmental pollutant monitoring,cell sensing,medical testing and other fields.Although Ru（bpy）₃²⁺and its derivatives and semiconductor quantum dot materials have good ECL performance,they have the characteristics of strong water solubility,which is not conducive to their immobilization on the electrode surface.This could decrease the analytical performance of ECL sensors and increase the loss of luminophore materials,limiting their application in ECL sensing analysis.In this paper,Ru（bpy）₃²⁺and CdS:Mnquantum dots are combined with MOF materials respectively to prepare composites with excellent ECL intensity and ECL stability.At the same time,in order to improve the selectivity,sensitivity and accuracy of ECL sensor,aptamers with specific affinity with targets,DNAzyme walker with cyclic catalytic cutting function and ferrocene molecules with quenching effect on ECL signal are used in the construction of ECL sensor to realize the rapid,ultrasensitive and selective detection of marine antibiotic pollutants.The main contents of this paper are as follows:1.An"on-off-on"type electrochemiluminescence aptasensor based on Ru@Zn-oxalate MOF composites and its application in the detection of sulfadimethoxineIn this work,an"on-off-on"type ECL aptasensor based on Ru@Zn-oxalate MOF composite is proposed for the highly selective and sensitive detection of SDM.Ru@Zn-oxalate MOF with excellent ECL performance is used as the luminophore and ferrocene（Fc）molecule is used as the switch of the sensor ECL signal regulation.Through the specific recognition and binding between SDM and its aptamer,the sensor can realize the high sensitivity and high selectivity detection of SDM.At the same time,the construction strategy of"on-off-on"ECL aptasensor can also significantly reduce the false positive signal and improve the analysis performance of this sensor.The proposed ECL aptamer sensor has good analytical performance compared with other methods for the detection of SDM with a detection range of 100f M-500 n M and a detection limit as low as 27.3 f M.The sensor also showed satisfactory analytical results in the analysis of actual seawater samples,and was expected to play a role in the detection of marine environmental pollution.2.An electrochemiluminescence biosensor based on Ru@MOF composite and DNAzyme walker cyclic amplification technology and its application in the detection of kanamycinIn this work,an ECL biosensor for ultrasensitive and selective detection of KANA was constructed by assembling DNAzyme walker on the surface of Ru@MOF modified electrode with KANA aptamer as a padlock chain and the catalytic cleavage of substrate chain by Ag⁺-DNAzyme.In this sensor,ferrocene（Fc）modified at one end of the substrate chain has a significant quenching effect on the ECL signal of Ru@MOF,and the ECL signal intensity of Ru@MOF can be changed by adjusting the content of ferrocene on the electrode surface.It is beneficial to improve the sensitivity of the sensor.In the presence of KANA,the KANA aptamer will specifically bind to KANA,so that the DNAzyme and the substrate chain form an enzyme structure.The specific recognition and binding between KANA aptamer and KANA ensured the good selectivity of the sensor in the detection process.In the presence of Ag⁺,the catalytic activity of DNAzyme is activated,which would cut the complementary substrate into two pieces.After the cleavage,the DNAzyme will re-combine with the uncut substrate chain for the next catalytic cleavage,so that a large amount of ferrocene leaves the electrode surface to amplify the ECL signal of this sensor and further improve its sensitivity.Happily,the ECL biosensor exhibited excellent detection performance for KANA with a detection range of 30 p M to 300μM,a detection limit as low as 13.7 p M.The sensor also showed satisfactory practical application results in the detection of actual seawater samples.3.An electrochemiluminescence aptasensor based on a novel luminescent material CdS:Mn@HZIF-8 and its application in the detection of sulfadimethoxineIn this work,an ECL aptasensor was constructed for fast,sensitive and highly selective detection of SDM using the prepared novel electrochemiluminescence composite CdS:Mn@HZIF-8.In this sensor,the successful combination of CdS:MnQDs and HZIF-8 reduces the diffusion of CdS:MnQDs in aqueous solution,which makes the CdS:Mn@HZIF-8 illuminant has good ECL performance.The electrode modified with CdS:Mn@HZIF-8 can immobilize the SDM aptamer modified with ferrocene on the surface of the modified electrode through electrostatic adsorption andπ-πstacking,thereby quenching the ECL signal of CdS:Mn@HZIF-8.In the presence of SDM,the SDM aptamer will specifically bind to SDM and leave the surface of CdS:Mn@HZIF-8/GCE to restore the ECL signal of the sensor and realize the selective and sensitive detection of SDM.The linear detection range of the proposed ECL aptamer sensor for SDM is 100 p M-1 m M and the detection limit is 28.6 p M.The sensor has the advantages of simple construction process and rapid detection.It also has a good effect on the detection of SDM in actual samples.