Study On The Interaction Of AgNPs With Flavonoids And Its Analytical Applications

Nucleic acid is the physical basis of life. It not only is the basic genetic material, but also occupies an important position in protein biosynthesis. Nucleic acid is biological macromolecules that are composed of many nucleotides polymerized. Therefore, it plays a decisive role in growth, heredity, variation and a series of other major biological phenomena. The small molecules and nucleic acids interaction studies play a significant role in clinical medicine, pharmacy and life sciences. Thus the determinations of the nucleic acid, study of interaction of small molecule drugs and nucleic acids are crucial for the synthesis of new drugs and clinical testings.Flavonoids are widely distributed in various plants. Large amount of flavonoid compounds have been found from natural product till now and most of them have important physiological and pharmacological effects. The special chemical structure of flavonoids has been fully applied in fluorescence analysis.This paper established a method to measure nucleic acid by flavonoid compounds fluorescence probe, and preliminary discussed the interaction between nucleic acids and different types of flavonoid by ultraviolet absorption spectroscopy, circular dichroic, transmission microscopy, fluorescence microscopy and some other methods. Silver nanoparticles-flavonoids composite nanoparticle probes were applied in nucleic acid agarose gel electrophoresis analysis and cell imaging experiment.In the first part of the paper, we reviewed the research on the pharmacological influence of flavonoids pharmacological to organism, as well as the application of silver nanoparticles in biological macromolecules analysis.In the second chapter, we discussed the preparation conditions of silver nanoparticles (AgNPs) by means of electrochemical reduction. The properties of AgNPs stabilized with PVP K30were superior to others.In the third chapter, we delved into the interaction mechanism of the system of quercetin-AgNPs and nucleic acids. Ultraviolet and Visible Spectroscopy(UV-vis), circular dichroism(CD), fluorescence polarization(FP), transmission electron microscopy(TEM) and other techniques were utilized. We belive that the interaction of B-and C-ring of quercetin and nucleic acids occured, nucleic acids worked as the bridge and they attached on the surface of AgNPs resulting in the fluorescence enhancement of the system. That is attributed to the surface enhanced fluorescence of the AgNPs. And the nanoparticle complex probe of quercetin-AgNPs were used in agarose gel electrophoresis coloration and cell microscopy imaging analysis.In the fourth chapter, the fluorescence characteristics of the systems of myricetin(Myr)-nucleic acid with and without AgNPs was studied. It is found that nucleic acids could enhance the fluorescence of myricetin, and the presence of AgNPs could further enhance the fluorescence in the system. And in optimum conditions, the extent of fluorescence enhancing and nucleic acids concentration showed a linear relationship in a certain range. The results showed that the linear range of herring sperm DNA (hsDNA), salmon sperm DNA (smDNA), calf thymus DNA (ctDNA) and yeast RNA (yRNA) were9.0×10-9-1.2×10-6g/ml,9.0×10-9-1.0×10-6g/mL,1.0×10-8-1.0×10-6g/mL and9.0×10-9-1.0×10-6g/mL, respectively, and the detection limits were3.1×10-9g/mL,6.8×10-9g/mL,8.310-9g/mL and7.0×10-9g/mL, respectively. This result shows that the method has a high sensitivity and a wide linear range. We also used it for the determination of the actual sample with satisfactory results. Mechanism investigations of the systems indicated that nucleic acids combined with myricetin attached on the surface of AgNPs, and online self-assembly of AgNPs, forming a cubic-shape luminescence nanocrystal.Highlights of this paper:[1] Silver nanoparticles(AgNPs) were prepared by electrochemical reduction reduction method. The effect of a variety of stabilizers on characteristic of AgNPs was studied, AgNPs stabilized with PVP K30was chosen for fluorescence enhancement analysis.[2] Based on the preliminary study, the interaction mechanism of quercetin, AgNPs and nucleic acids was studied. A nanoparticle complex probe of quercetin-AgNps was applied in nucleic acid agarose gel electrophoresis analysis and Arabidopsis protoplast cell imaging.[3] The fluorescence characteristic of the system of myricetin-nucleic acid with and without AgNPs was studied, a new method for the determination of nucleic acids and established, the results indicate that AgNPs can effectively increase the stability of the fluorescence of the system. The luminescence nanocrystal occurred in the system.