Design,Synthesis And Evaluation Of Small Molecule Fluorescent Probes For Detection Of Divalent Palladium And Cysteine

As fluorescent substances that can specifically identify ions and biological small molecules and macromolecules,fluorescent probes are widely used in biological,physiological,pharmacological,environmental and medical tests due to their advantages of high sensitivity,low detection limit,strong specificity and simple operation.The heavy metal palladium?Palladium,Pd?is widely used in the manufacture of household and industrial supplies such as electrical appliances,fuel cells and converters.And as an important chemical catalyst,it is widely used in chemical research and drug synthesis.Therefore,the development of sensitive and specific detection methods about palladium has become an increasingly urgent issue in environmental and biological systems.In the second chapter,a small molecular weight and low toxicity Pd²⁺fluorescent probe Umb-Pd2 was designed and synthesized with the excitation wavelength of 322 nm and the emission wavelength of380 nm.After co-incubation with Pd²⁺,the emission wavelength was redshifted to 450nm,and the limit of detection?LOD?was 1.1 n M,the linear range of detection limit was 0-18?M,and the fluorescence intensity remained stable at p H 5-10.With4-methyl umbelliferone as fluorophore and propinyl as recognition group,Umb-Pd2can specifically distinguish Pd²⁺and Pd?0?based on the reaction mechanism of photoinduced electron transfer?PET?,and the fluorescence intensity reaches saturation after co-incubation for 30 min.Meanwhile,we successfully performed confocal imaging to detect Pd²⁺on He La cells through using fluorescence imaging technology,indication that the probe has potent cell permeability.Umb-Pd2 is expected to be further developed as an important tool for monitoring palladium catalytic reaction process and detecting palladium ion concentration in biological organisms.Cysteine?Cys?is an essential amino acid whose main functions include monitoring metabolic processes and maintaining dynamic REDOX balance.Abnormal cysteine levels lead to a series of physiological and pathological changes in the body.Therefore,the development of cysteine detection methods that are compatible with modern medical methods plays an important role in medical research.In the third chapter,a fluorescent probe Qui Cys containing quinoxaline derivative was designed and synthesized,with the excitation wavelength of 410 nm and the emission wavelength of 466 nm.After co-incubation with Cys,the emission wavelength was red shifted to 533 nm,the limit of quantification?LOQ?was 100 n M,and the fluorescence intensity remained stable at p H 7-11.Qui Cys does not respond to other sulfur compounds including GSH.The co-incubation time was 100 min when the fluorescence intensity reached saturation.Qui Cys has the characteristics of low toxicity and high permeability,and could quantitatively detect exogenous and endogenous C ys.This work not only provides practical tools for C ys detection,but also provides referable information for the optimization strategy of fluorescent probe.The development and optimization of the above two ratio fluorescent probes have been successfully applied to the study of confocal imaging to achieve the purpose of real-time monitoring of Pd²⁺and Cys.Fuithermore,the ratio fluorescent probes have the characteristic of less background interference tha the ordinary fluorescent,which is turn-on probe or turn-off probe.In the following work,we will further optimize the structure of Umb-Pd2 and Qui Cys,so as to apply them into the preclinical detection.