The Preparation Of Tetraphenylethylene Functionalized Covalent Organic Frameworks And Their Applications In Aggregation-Induced Electrochemiluminescence Biosensors

Micro RNAs（mi RNAs）as a kind of well-known cancer markers whose abnormal fluctuation in expression level is closely related to the disease and can be used to indicate the occurrence of the disease.Therefore,developing effective methods for mi RNAs assays has great significance for disease diagnosis,pathological research and relevant fields.Electrochemiluminescence（ECL）is a luminous phenomenon that the luminescent molecules in excited state which produced by electrochemical reactions under the action of external potential returns to the ground state and produce photon.The unique mechanism endows this technique with inherent advantages of low background signal,response quickly and high sensitivity,thus,ECL has been widely studied and applied in chemical,biological,medical and environmental analysis.Hence,the selection of ECL emitter is particularly important.Tetraphenylethylene（TPE）stands out because of its advantages of simple structure,adjustable luminescence and easy modification among the novel aggregation-induced electrochemiluminescence（AIECL）materials which has been widely researched in recent years due to their high luminescence efficiency,photobleaching resistance and good biocompatibility.Covalent organic framework withπ-rich electrons and highly ordered topology were selected as carriers of TPE to provide more recognizable biomolecular recognition domains,improve stability of TPE and achieve efficient AIECL emission,for the reason that the structure of TPE is not easy to be labeled and their insolubility in water limits their application in biological studies.Based on this,two kinds of AIE-functionalized nanocomposites were synthesized in this study.In this paper,AIECL biosensors were constructed by combining with resonance energy transfer strategy and were successfully utilized for quantitative analysis of mi RNAs.The research content of this paper mainly includes the following two parts:（1）TPE-COFs based aggregation-induced electrochemiluminescence sensor for the detection of mi RNA-21TPE-doped covalent organic frameworks（TPE-COFs）has been synthesized,which realized the effective limitation of TPE molecular motion and has a strong aggregation-induced electrochemiluminescence（AIECL）response and good stability.A novel TPE-COFs based AIECL biosensor was constructed which combined with resonance energy transfer technology,for ultrasensitive detection of the mi RNA-21 using the differential signal readout,with the limit of detection（LOD）was 2.18 a M.The selectivity,stability and reproducibility of the sensor were evaluated,meanwhile,RT-PCR method was used to compare the detection results of the proposed sensor,which demonstrated the reliability of the strategy of the proposed sensor.（2）Functionalized TPE-COFs based aggregation-induced electrochemiluminescence sensor for the detection of mi RNA-221In this paper,the morphology of TPE（COOH）₄-COFs was regulated by adjusting the drop acceleration of the catalyst,and the doping of AIE molecule was realized by using the intermolecular force.Therefore,the ECL signal was significantly enhanced and the fluorescence lifetime was gradually enhanced with the slowing down of catalyst droplet acceleration,due to the porosity and ordered topological structure of COFs effectively limited the molecular motion of TPE（COOH）₄-COFs.Subsequently,the AIECL biosensor was constructed by combining the resonance energy transfer technique and the differential signal readout to achieve the quantitative detection of mi RNA-221,with the limit of detection was1.85 a M.The performance evaluation of the AIECL sensor also demonstrated the potential application value of this strategy in analytical applications.