Study On Synthesis And Application Of Novel Fluorescent Dyes In Environmental Monitoring

With the increasing of the variety and the amounts of environmental pollutants, the demands for the sensitivity, accuracy, specificity, and accessibility et al. of analytical methods of environmental pollutants become higher and higher. There are many methods to analyze pollutants however, more and more researchers at home and abroad pay attention to fluorescence analytical methods for its high sensitivity, selectivity and other advantages. In this dissertation, a series of novel fluorescence dyes of rare earth complexes with long life fluorescence time, naphthalimide, and anthracene derivatives were designed and synthesized. The dyes were then applied in the detection of pathogenic microorganisms, trace metal ions, or water content in envrionment. The developed detection systems both have satisfactory sensitivity and were easy to operation.The details are summarized as follows:(1) A two-probe tandem DNA hybridization assay including capture DNA1, probe DNA2, and target DNA3 was prepared. Some kinds of rare earth complex were synthesized. The long-lived luminescent europium complex doped nanoparticles (NPs) were used as the biomarker. The complex included in the particle was Eu(TTA)3(5-NH2-phen)-IgG (ETN-IgG), the europium complex Eu(TTA)3(5-NH2-phen) linking an IgG molecule. Silica NPs containing ETN-IgG were prepared by the reverse microemulsion method, and were easy to label oligonucleotide for time-resolved fluorescence assays. The luminophores were well-protected from the environmental interference when they were doped inside the silica network. The sequences of Staphylococcus aureus and Escherichia coli genes were designed using software Primer Premier 5.0. Amino-modified capture DNA1 was covalently immobilized on the common glass slides surface. The detection was done by monitoring the fluorescence intensity from the glass surface after the hybridization reaction with the NPs labeled probe DNA2 and complementary target DNA3. The sensing system presented short hybridization time, satisfactory stability, sensitivity, and selectivity. This approach was successfully employed for preliminary application in the detection of pure cultured E. coli, it might be an effective tool for pathogen DNA monitoring (chapter 2).(2) Based on the above detection assay, the single molecule with a functional group of amino and strong long lifetime fluorescence was directly used as the biomarker. The Eu complex of Eu(TTA)3(5-NH2-phen) was linked to the probe DNA. High sensitivity showed that the proposed DNA detection system based on such complex molecular could be more convenient than nanoparticle-based detection systems. The sensing system presented short hybridization time, satisfactory stability, and high selectivity (chapter 3).(3) A novel fluorescent dye,9-anthraldehyde-thiosemicarbazone (AnthT), used for the determination of Cu(Ⅱ) or Hg(Ⅱ) in aqueous solutions was described. In the presence of several metal ions such as Na(Ⅰ), Al(Ⅲ), Ba(Ⅱ), Mn(Ⅱ), Co(Ⅱ), Cd(Ⅱ), Ca(Ⅱ), Zn(Ⅱ), Cr(Ⅲ), Fe(Ⅲ), Pb(Ⅱ), Hg(Ⅱ), and Cu(Ⅱ) at a same concentration of 5.0×10-5 mol L-1, only Hg(Ⅱ) and Cu(Ⅱ) resulted in remarkable decreases. The fluorescence intensity of the probe decreased with increasing concentration of Cu(Ⅱ) or Hg(Ⅱ) when it was excited at 411nm in water-ethanol (20/5 v/v) solutions at pH 7.20. The fluorescence intensity of the probe decreased with increasing concentration of Cu(Ⅱ) or Hg(Ⅱ). The thiourea derivative-based probe showed linear response toward Hg(Ⅱ) in the concentration range ca.2×10-6-4×10-5 mol L-1 and Cu(Ⅱ) ca. 1×10-7-1×10-5 mol L-1. The prepared sensing system presented satisfactory sensitivity and selectivity, and the detection limits could be as low as 8.9x10"8 mol L-1 for Hg(Ⅱ) and 3.3×10-8 mol L-1 for Cu(Ⅱ). The developed method was successfully employed for preliminary application in natural water and domestic sewage (chapter 4).(4) A new fluorescent dye, N-allyl-4-morpholinyl-1,8-naphthalimide (AMN), was synthesized as a fluorescent indicator in the fabrication of a sensor for determining water content in organic solvents. AMN was photo-copolymerized on a glass surface treated with a silanizing agent. The fluorescence intensity of AMN decreased with increasing water contents when it was excited at 400 nm. In the range of ca.0.00-4.40%(v/v), the fluorescence intensity of AMN changed as a linear function of water content. The sensor exhibited satisfactory reproducibility, reversibility, and a quick response time. The leakage of the fluorophore was successfully prevented through covalently immobilization. Additionally, the prepared sensor is pH-insensitive and possesses a relatively long lifetime of at least one month (chapter 5).(5) Another benzothioxanthene derivative of N-(2-methacryloxyethyl) benzo[k,l]thioxanthene-3,4-dicarboximide (MBTD), was used as a fluorescent indicator for determination of water content in organic solvents. MBTD was also photocopolymerization-immobilized on a glass surface. Fluorescence spectra of the sensing membrane were recorded in various solvents of different polarity. The solvent exerted an evident influence on the fluorescence intensities and stokes shift. And the fluorescence intensity of MBTD changed as a linear function of water content in a certain range. The prepared sensor system possesses short response, and recovering time. The reversibility and reproducibility are also adequate for practical measurement (chapter 6).(6) While preparing various fluorescence sensing systems, other novel fluorescence dyes were synthesized. In the last chapter, synthesis of some other fluorescence dyes with super luminescence properties were described (chapter 7).