The Research On The Novel Biochemical Analysis Methods Based On The Fluorescent Regulation Of Thioflavin T

At home and abroad, the design of fluorescence molecular probes and their applications have attracted a lot of attention in current research. Fluorescence molecular probes have many advantages. For example, they only need simple operation and are not influenced by electric/magnetic field. Morever, the analysis results are accurate and reliable with rapid response and good selectivity, which can realize real-time, in-situ, single molecule analysis detection and obtain high sensitivity. As a result, the development of novel fluorescent molecular probes is a significant content in a variety of fileds, such as food security, medical, agriculture and environmental science, etc.This research focus on novel biochemical analysis methods based on the fluorescent regulation of Thioflavin T (ThT). In the context of the current growing trend of this field, we have further developed some new fluorescence molecular probes via different confining systems like simple cation and anion, DNA and lanthanide/nucleotide coordination polymers to induce the "off-on" fluorescence regulation of ThT. Our purposed fluorescence molecular probes have been used for the rapid detection of metal ions (Ag+), anion (I-) and environmental parameters (temperature) with high sensitivity and good selectivity, which provides a new thought and method for environmental monitoring and protection, food and drug safety, medical diagnosis and clinical treatment, biochemical analysis and other important areas. The full text is divided into four parts, as follows:Chapter 1. OverviewFirstly, This chapter first introduces several common fluorescence molecular probes and the research progress, and then emphatically discusses thioflavin T (ThT) dye, including the optical properties, the control strategy of the "off-on" fluorescence regulation of ThT, the research progress of fluorescent probe based on ThT. Finally elaborated the significance of this thesis research and the main content.Chapter 2. The "off-on" fluorescence regulation of Thioflavin T induced by simple cation and anion and ratiometric fluorescence detection of silver ionsWe present a new type of small molecule-NP hybrid suparparticles that spontaneously assemble from Ag+, I- and thioflavin T (ThT) under an aqueous solution condition, which can be employed for ratiometric fluorescent detection of Ag+with high sensitivity and selectivity. The linear range of detecting Ag+ was from 0.1μM to 10 μM, with a limit of detection as low as approximately 50 nM. ThT in water alone was weakly fluorescent with emission band at 494 nm, which was related to the monomer. However, in the above-mentioned hybrid supraparticles (i.e., ThT@AgI SPs) structure, the ThT monomer can form dimer with a new emission band. The new band shifted to 546 nm and the emission intensity increased. Morever, it can be successfully applied for operation of a logic gate system and to the sensing of Ag+in water samples. We further present a facile strategy of reversible fluorescence switch of ThT by simple cation (Ag+) and anions (I-and S2-). This is a new scope of control strategy for the "off-on" fluorescence regulation of ThT, and it opens an opportunity for the design of more methods based on the simple cation-anion strategy.Chapter 3. The "off-on" fluorescence regulation of Thioflavin T induced by DNA and label-free fluorescence detection of iodide ionsWe have developed the novel label-free detection method based on "molecular beacon (MB)" for iodide (I-) utilizing ThT dyes, a label-free MB-like probe consisting of a mercury ions (Hg2+)-specific DNA (MSD) and Hg2+ions in a convenient one-step approach. We have investigated the analytical performance of this probe (selectivity, sensitivity and the limit of detection). The proposed method exhibited very good selectivity to I- ions over 10-folds concentration of other anions interference due to the strong binding force between I- ions with Hg2+. To improve the detection selectivity, a common the thiol-based compound scavenger, N-ethylmaleimide (NEM), was introduced to eliminate the interference of biothiols in the assays for I- with high selectivity. The linear range of detecting I- ions was from 0.5 μM to 6 μM, achieving a limit of detection as low as 158 nM. In addition, it was successfully applied for operation of an integrated DNA logic gate system and to the determination of I- in real samples such as human urine with satisfactory results.Chapter 4. The "off-on" fluorescence regulation of Thioflavin T induced by lanthanide/nucleotide coordination polymers and label-free fluorescence detection of temperatureWe presented a simple, label-free and rapid-responsive fluorescence assay for temperature detection based on a type of thioflavin T (ThT)-doped lanthanide/nucleotide coordination polymers by the self-assembly of ThT, europium ions (Eu3+) and nucleotide (guanosine monophosphate, GMP) in aqueous solution (i.e. ThT/Eu/GMP). The Eu/GMP coordination polymers show excellent adaptive inclusion properties for ThT in a convenient one-step approach, which can readily enhance the fluorescence of ThT via the restricted effect. We have investigated the feasibility of this probe as a temperature sensor. The results show that the as-prepared hydrophilic ThT/Eu/GMP coordination polymers have the capability of acting as a temperature-sensitive, visual and reversible sensor in aqueous solution under the irradiation of visible light. Our proposed design is cost-effective and simple to prepare without chemical modification or fluorescence labeling.Chapter 5. Summary and outlookThis chapter summarizes the significance and innovative features of the aboved works, and prospects the future development in this field.