| Deoxyribonucleic acid is an important hereditary material. The basevariation of DNA is tightly related to genetic diseases. Protein is one of the importantparts of organism. The quantity changes of protein in the human body may lead topathological changes, so it is important to detect DNA sequence and protein sensitivelyfor disease diagnosis and clinical applications.Fluorescence is becoming increasingly promising method for biomedical andenvironmental analysis because of its advantages such as simple instrumentation, highsensitivity, simplicity and rapidity.This thesis includes a review and a research section. In the review section, thebasic principles, characteristics and the applications of fluorescence in DNA and proteinanalysis are introduced. Development of various kinds of fluorescence labels is mainlyreviewed. Finally, the purpose and content of the research work in this thesis arepresented.The research section contains two subunits. In the first subunit, the fluorescencesignal amplification of DNA hybridization was studied, which was based on dye-dopedsilica nanoparticles used as fluorescence probe. The fluorescence emission enhancementwas significantly observed upon DNA probe hybriding with target DNA which wasattached on the surface of magnetic nanoparticles. It was found that DNA could bequantified in good linearity range of 1.2×10-14～2.5×10-13 mol/L with a low detectionlimit of 1.6×10-15 mol/L, and the relative standard deviation for 6.7×10-14mol/L DNAwas 2.6%(n=11). The method developed was sensitive, simple and suitable for thedetermination of DNA sequence.In the second subunit, a new strategy of fluorescence assay for protein based onDNA duplex containing AP site was proposed. In this work, a novel label freefluorescence method for homogeneous detection of thrombin, which chosen as a modelprotein, was developed on basis of dsDNA containing AP site and aptamer. Aptameragainst thrombin and amiloride was used as a molecular recognizer and a fluorescencereporter, respectively. In the absence of thrombin, the aptamer could hybridize with cDNA containing AP site in the highest degree and amiloride could bind to thymineopposite AP site in the DNA duplexes, resulting in fluorescence quenching. In theprescence of thrombin, amiloride exhibits enhancement of its fluorescence and theenhance degree was relative to the increase of the concentration of thrombin. Accordingto the fluorescence signal change, thrombin could be determined rapidly and sensitively.It was found that under optimal conditions the enhanced fluorescence intensity had agood linearity with the concentration of thrombin in the range from 4.2×10-9 mol/L to4.2×10-8 mol/L with a detection limit of 1.3×10-9 mol/L. The relative standard deviation(n=11) was 3.2% at 3.0×10-8 mol/L thrombin. This work demonstrated that the proposedmethod provides a promising strategy of fluorescence assay for protein based on DNAduplex containing AP site and an aptamer as molecular recognizer.
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