Research On Fluorescence Detection Techniques Based On DNA Probes

Contamination of the environment with heavy metal ions has been an importantworldwide concern for decades. So many harmful substances are put into the water. Thesesubstances are severely harmful to the human health. These ions do serious harm to thevarious aspects of the agriculture and industry. For the determination of trace amounts oftoxicions, various spectroscopic, electrochemical and radiochemical methods were used.The method developed in this work can be applied into the measurement of total inorganicmercury, phosphate, thrombin in real samples.Thrombin, a protein involved in the blood coagulation cascade, was the firstbiological macromolecule exploited for aptamer selection. Activation of thrombin iscrucial in physiological and pathological coagulation. Because of the thrombin’simportance in anticlotting therapeutics, thrombin-binding aptamer has been studiedextensively.Due to human activities，different anions have been released into the biosphere andaffected our daily life. Development of new optical phosphate chemosensors with highsensitivity and selectivity is very important, since phosphate play some fundamental rolesin a wide range of biological.Therefore, mercury, phosphate, thrombin molecule have already become the mostpopular analytes.There are four parts in our work:1. Detection of mercury ions in the real sample using the resonance lightscattering techniqueThe experiment use the resonance light scattering technique and this idea is based oniron oxide.The emerging approach to detect Hg2+involves the use of a T-Hg2+-T(thymine-Hg2+-thymine) complex. Owing to the high stability and selectivity, T-Hg2+-Tcoordination chemistry has been developed rapidly in recent years. Real samples includingtap water, river water and lake water samples were analyzed using the present sensorsystem. The magnetic particles aggregation resulted the enhancement of the fluorescence resonance technique signal.The proposed method is applicable to the determination of Hg2+in both standard solutions and water samples in the presence of excess of other metal ions,with a LOD down to500fM.2. To detect the mercury ions with the fluorescence polarization techniqueIn this work, we developed a sensitive and selective sensor technique for total mercury(Hg2+) detection in canned fish samples based on the fluorescence polarization (FP)method. DNA containing thymine (T) bases was attached on magnetic nanoparticles(MNPs), which were used as enhancement probe. In the presence of Hg2+, the ssDNA onMNPs can hybridize with the fluorophore labeled aptamer owing to the specific interactionbetween T bases and Hg2+.3. The assay of thrombin using nanoparticle-enhanced fluorescence polarizationA new aptamer biosensor was presented for the detection of thrombin in this work, whichwas based on fluorescence polarization (FP) using nanoparticles as enhancementprobe.The sensor provided a linear range from0.6to100nM for thrombin with a detectionlimit of0.20nM.And the sensor can be used to monitor spiked concentration of thrombinlevel in real human plasma.4. The detection of phosphate ions in analytes using the fluorescence techniqueA novel sensor was developed for the determination of phosphate based on the inducedelectron and energy transfer between zirconium ions and phosphorus ions.In this work, anovel sensor for phosphate was developed form a more sensitive detection system forphosphate. The developed method was applied in the detection of phosphate in realdetergent amples.