Application Of Coumarin-sensitized New Type Metal Iridium Complex In Photoelectric Biochemical Analysis

With the development of science and technology,Photoelectrochemical(PEC)analysis has gradually become a new and rapidly developing trace analysis technology.Compared with traditional electrochemical and optical detection technologies,PEC analysis has the advantages of low cost,fast detection speed,simple operation and high sensitivity,and has been widely used in environmental monitoring,drug analysis and detection,biological analysis and detection,food safety monitoring and other research fields.The photoelectric conversion efficiency of photoelectric chemical and biological analysis mainly depends on photoelectric active materials.At present,the photoelectric active materials used in photoelectrochemical bioanalysis have the disadvantages of wide band gap and weak absorption,which further limits the application in bioanalysis of PEC in the visible region.Therefore,it is still a great challenge to extend the absorption range of photoelectric active materials to the visible light region.Among many photoelectric active materials,metal complexes have become the focus of research due to their good photostability and thermal stability.As a typical metal complex,the ring metallized Ir(?)complex has more attractive photoelectric properties.At present,the application of iridium complex in the field of biochemical analysis is still in the preliminary stage.In view of the above reasons,based on the advantages of adjustable optical physical properties of ring metallized Ir(?)complexes in a wide range,two photoelectric active materials of ring metallized Ir(?)complexes with high molar absorbance in the long wave direction in the visible light range were designed and synthesized in this paper.The cathode photoelectric chemical sensing platform based on ring metallized Ir(?)complex was constructed and applied to the highly sensitive and selective detection of thrombin and DAM methyltransferase in the complex life system.The main contents are as follows:1.Photoelectric chemical sensor for thrombin detection based on coumarin sensitized ring metallized Ir(?)complexA cationic ring metallization Ir(?)complex[(CHO-bpy)₂Ir(C-phen)]⁺PF₆^-(CHO-bpy:4-(pyridine-2-yl)benzaldehyde for photoelectric active materials was designed and synthesized.C-Phen,the main ligand with light capture ability,covalently bonds coumarin to the auxiliary ligand o-phenorin),in which the covalently bonds the coumarin part to improve the absorption of the iridium complex in the visible region.The aldehyde group in the ring metallization ligands is beneficial for biomarkers of the complexes.The results of UV-Vis absorption spectra,photochemistry and electrochemistry indicated that the complex was a highly efficient photoactive material with stable and repeatable cathode photocurrent under visible light irradiation.The prepared[(CHO-bpy)₂Ir(C-phen)]⁺PF₆^-complex was used as a signal reporter,and the PEC nano-probe based on gold nanoparticles(Au NPs)was assembled.A simple,highly sensitive PEC biosensor was constructed for the determination of thrombin by means of chain replacement induced by aptamer/protein proximity binding and catalytic hairpin self-assembly amplification strategy(CHA).Due to the excellent photon-current conversion properties of the Iridium(?)complex,the effective amplification strategy,and good biocompatibility,the PEC biosensor platform has a higher sensitivity for thrombin detection with a good linear range of 50f M-20 p M and a detection limit of 23 f M.It also showed high specificity in actual serum samples.The biosensor platform has good selectivity,stability and repeatability,and has a certain development potential in the future medical field.2.Photocathode sensor for DNA methyltransferase detection based on coumarin-sensitized imbedded ring metal Ir(?)complexesAn imbedded cationic ring metal iridium complex[Ir(C6)₂(dppz)]⁺PF₆^-(ring metallization main ligand:C6=coumarin 6 and auxiliary ligand:dppz=dipyrophene and phenazine),which was characterized by UV-visible absorption spectroscopy(UV),photochemistry and electrochemistry.The results showed that the complex exhibited a highly sensitive and stable photocurrent signal with no attenuation in the visible region.In view of the excellent light capture ability and good biocompatibility of the complex,this paper reports for the first time the efficient[Ir(C6)₂(dppz)]⁺PF₆^-sensitized Ni O photocathode and its application in cathodic photochemical and biological analysis.The Ni O photocathode sensitized with the iridium complex exhibits a significantly enhanced cathodic photocurrent.This sensing platform combined with the enzyme-free cascade amplification strategy of catalytic hairpin self-assembly(CHA)and hybrid chain reaction(HCR)can realize the highly sensitive detection of DNA methyltransferase(MTase).The results show that the constructed photoelectric biosensor platform has a good linear relationship in the range of0.005-100 U/m L,and the detection limit is 0.0028 U/m L.At the same time,it has excellent performance of selectivity,stability and repeatability.In addition,this study further demonstrated that the biosensor platform can be applied to the screening of DNA methyltransferase(MTase)active inhibitors.So as to provide a reliable biological analysis method for the new generation of clinical diagnosis of cancer.