Study On Electrochemiluminescence Biosensor Based On Postmodification Of Highly Stable Mesoporous Metal-Organic Frameworks

In recent years,metal-organic frameworks（MOFs）have captured more and more attention for their large surface areas,permanent porosity,easily tailorable pores,and functions.As a result,MOFs have potential applications in the fields of gas storage,separation,catalysis,drug delivery and sensing.MOFs could greatly increase the immobilization number of luminophores because of the large surface areas of MOFs,they have many potential applications in the construction of electrochemiluminescence（ECL）sensor.However,most MOFs have low stability in aqueous environments,resulting in the leaching of luminophores in the testing process,which can affect the stability of ECL sensors.Therefore,it is necessary to seek highly stable mesoporous MOFs to immobilize luminophores through a stable immobilization strategy.Based on the above points,a series of ECL biosensors with excellent performance were constructed by using highly stable MOFs to load ruthenium-complex for detection of mucin 1（MUC1）.The prepared MOFs were characterized by powder X-ray diffraction（PXRD）,the scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,atomic force microscopy（AFM）,and inductively coupled plasma-optical emission spectroscopy（ICP-OES）.This paper indicate that using highly stable MOFs to load luminophores is a feasible strategy for the design of high-performance ECL materials,which is helpful for the development of new methods to develop highly sensitive ECL sensors.The research work of this paper is mainly divided into the following parts:Part 1 Postmodification of highly stable mesoporous MOFs（PCN-777）and itsapplicati on to ECL sensorIn this work,PCN-777 was prepared by the reaction of ZrOCl₂·8H₂O and4,4′,4′′-s-triazine-2,4,6-triyl-tribenzoic acid（H₃TATB）.And then,Ru-PCN-777 was prepared by grafting ruthenium complex onto PCN-777 based on the strong coordination bond between Zr⁴⁺and-COO^-,and further immobilized with polyethylenimine（PEI）and gold nanoparticles（AuNPs）to obtain AuNPs-PEI@Ru-PCN-777.AuNPs-PEI@Ru-PCN-777 has the following advantages:firstly,PCN-777 is a mesoporous MOF with high water stability,and therefore,ruthenium complexes can not only exist on the surface of PCN-777,but also graft into the interior of PCN-777,which will greatly increase the loading amount of ruthenium complexes.Secondly,Ru-PCN-777 shows good chemical stability in water for the reason that the ruthenium complex is coordinated to the Zr₆ nodes of PCN-777 via the strong coordination bond between the carboxyl group of the ruthenium complex and the metal cluster of PCN-777,which effectively avoids the leakage of the ruthenium complex in the testing process.Thirdly,because of the mesoporosity of PCN-777,the Ru（bpy）₂（mcpbpy）²⁺on the surface and interior of PCN-777 could be effectively excited by the electrons,which leads to the the increasing utilization ratio of the ruthenium complexes.Considering these mentioned advantages of AuNPs-PEI@Ru-PCN-777,we used it to construct ECL sensor and realized the ultrasensitive detection of Mucin 1（MUC1）by combining other signal amplification strategies.Part 2 Postmodification of 2D MOFs nanoplates and its application to ECL sensorMetal-organic frameworks（MOFs）have received more and more attention in ECL immunoassays because their well-ordered porosity and high surface area could greatly increase loading capacity of luminophores.However,the utilization ratio of the luminophores is limited by the long ion/electron migration paths and ion/electron diffusion constraints in MOFs.In order to overcome these shortcomings,we utilized 2D MOFs nanosheets nanoplates to load luminophoresthe,which could effectively short the ion/electron transport distance and relieve the diffusional constraints of ion/electron,resulting in the high utilization ratio of the luminophores and strong ECL emission.Hence,in this work,2D MOF nanosheets（Hf-MOL）was prepared by the reaction of HfCl₄,and 4,4’,4’’-benzene-1,3,5-triyl-tri-benzoic acid（H₃BTB）.Then,the Ru（bpy）₂（mcpbpy）²⁺was grafted into Hf-MOL through the strong coordination bond between Hf⁴⁺and-COO^-.After polyethyleneimine（PEI）as modifief on Ru-Hf-MOL as coreactanton,PEI@Ru-Hf-MOL could be obtained.Considering these mentioned advantages of MOL,this work utilized the prepared PEI@Ru-Hf-MOL to construct ECL sensor based on target-induced proximity hybridization for realizing the simple,fast and ultrasensitive detection of the target MUC1.