Study On Highly Sensitive Detection Of Dopamine/Ferulic Acid Based On Micro/Nanoparticles Enhanced-Fluorescence

Dopamine(DA)is an important neurotransmitter of catecholamines.It involves in the regulation of various physiological activities in the body.The abnormal levels of DA can cause a variety of neurodegenerative diseases.Ferulic acid(FA)is a kind of phenolic acid.FA exists in all kinds of plants and is an effective component of many traditional Chinese medicines.Both DA and FA have various functions,such as anti-oxidation,anti-tumor and participating in the regulation of cardiovascular and cerebrovascular physiological functions.And they are widely used in clinical medicine and other fields.Therefore,the study of highly sensitive detection and analysis methods of DA and FA has potential application value and important significance for the in-depth understanding of their pathogenic mechanism and pharmacological action.Fluorescence analysis method is one of the most commonly used analytical techniques in the field of analytical chemistry with high sensitivity,good selectivity,simple operation and low cost.In this paper,a simple,rapid,specific and highly sensitive fluorescence analysis method for phenolic amines/phenolic acids was established based on the fluorescence signal amplification strategy.In addition,the mechanism of fluorescence enhancement and the interaction between the components of the system were studied by means of UV-visible absorption spectra,Zeta potential,dynamic light scattering,resonance light scattering,transmission electron microscopy,fluorescence lifetime,fluorescence polarization,infrared spectra,Raman spectra and other technological means.The specific research contents are as follows:the first chapter is the introduction,which summarizes the research background and progress of analytical methods of DA and FA,and briefly summarizes the application of sensitization enhancement of rare earth complexes,metal enhanced fluorescence(MEF)effect and enrichment in the field of analytical chemistry.In Chapter 2,based on the MEF effect of AuNFs,a trace detection and analysis method of DA was established.Anisotropic AuNFs with rich edges and corners have highly polarized local charges at the edges and corners,which can focus isoplasmon resonance electromagnetic fields and form rich electromagnetic hot spots.As MEF matrix,AuNFs have excellent fluorescence enhancement ability,which can significantly improve the detection sensitivity.DA and Tb3+form complexes to sensitize the characteristic fluorescence of Tb3+,and DA as a bridging agent could adjust the proper distance between Tb3+-DA and AuNFs.The characteristic fluorescence of Tb3+was enhanced by the synergistic effect of the sensitization of Tb3+fluorescence by DA and the MEF effect of AuNFs.Under the best experimental conditions,the characteristic fluorescence of Tb3+ was very sensitive to the change of DA concentration.The fluorescence intensity increment at 545 nm showed a good linear relationship with DA concentration in the range of 0.80-300 nM,and the detection limit was 0.21 nM(S/N=3).The method had been applied to the determination of DA in people serum and dopamine hydrochloride injection samples with satisfactory results.In Chapter 3,the highly sensitive detection of FA was realized based on the synergistic enhanced fluorescence effect of FA and Mg2+coordination and the adsorption and enrichment of the complexes on the Mg2+·Mg(OH)2 particles.In KCl/NaOH buffer medium with pH=12.30,Mg2+ precipitated to form Mg2+·Mg(OH)2 microparticles,and the coordination of fully protonated FA with Mg2+on the surface of Mg2+·Mg(OH)2 microparticles enhanced their coplanarity and rigidity.Moreover,The FA-Mg2+complexes were enriched on the surface of the microparticles,and the Mg2+ ·Mg(OH)2 microparticles were induced to aggregate to form a larger volume of network flocculent structure aggregates,resulting in a significant enhancement on the fluorescence of the system.The fluorescence intensity had a good linear relationship with FA concentration in the range of 0.40 nM-1000 nM,and its detection limit could be as low as 0.27 nM(S/N-3).And this analytical method was applied to the determination of FA content in sodium ferulate tablets with satisfactory results.