Study On The Applications Of Some Porphyrin, Cyanine And Phthalocyanine Compounds In Nucleic Acid Assay

This thesis developed several new methods for the determination of nucleic acidsemploying some porphyrin, cyanine and phthalocyanine compounds as probes, by meansof resonance light-scattering, fluorescence enhancement method, shifting theion-association equilibrium and kinetic fluorometric method. The thesis consisted of sixchapters. In chapter 1, recent progress of fluorescence analysis and probe research wasreviewed. Then, the research proposal for this thesis was presented. In chapter 2, the reagents, apparatus and synthesis of some probes used by this workwere described. In chapter 3, using resonance light-scattering (RLS) technique, the interaction oftetra-(N-hexadecylpyridiniumyl) porphyrin with nucleic acids in the presence ofsurfactant cetyltrimethylammonium bromide was investigated. And a sensitive RLSmethod for the determination of nucleic acids was developed. Chapter 4 was divided into two parts. In part one, a fluorescence enhancement method was proposed for the determinationof nucleic acids based on the enhancement effect of DNA on the fluorescence of a cationcyanine. In addition to its rapid reaction, high sensitivity and good reproducibility, themethod had a rather wide linear range (beyond three orders of magnitude). The spectrainvestigation disclosed that the fluorescence enhancement could be attributed to thefollowing possible reasons: (i) the cyanine was bound in the form of monomer into theminor groove of DNA, and the wall of the minor groove inhibited the excited-statetwisting and the nonradiative decay of the dye; (ii) the cyanine dye spontaneouslyassembled into the double-helical DNA template to form helical J-aggregates. In the second part, the effect of DNA on the ion-association equilibrium between ananion cyanine and poly-amino acids polypeptide was studied. The anion cyanine couldnot be directly employed to determine nucleic acids due to no evident interaction betweencyanine and DNA. However, it could intensely interact with opposite charged poly-lysine.The free anionic cyanine was highly fluorescent in solution. In the presence ofpositively charged polymers, protonated poly-lysine (pKa?9.9), the fluorescence ofcyanine was almost completely quenched, however, the cyanine regained its originalfluorescence if nucleic acids were added. Based on this phenomenon, a novel IIIＡｂｓｔｒａｃｔnear-infrared (near-IR) fluorescence recovery method for the quantification of nucleicacids was presented. The main advantage of this method was that both the fluorescenceexcitation and emission were located in the near-IR region (778/804nm), so thebackground interference induced by bio-molecules or matrix could be greatly overcome. Chapter 5 was divided into three parts. In part one, high sensitive determination of nucleic was developed employing atwo-regent system which was composed of an anionic tetracarboxy aluminumphthalocyanine and a cationic tetra-(N-hexadecylpyridiniumyl) porphyrin. In part two, tetracarboxy aluminum phthalocyanine-Poly-lysine-nucleic acids ion-association equilibrium system was studied and applied in the quantification of nucleicacids. This method was characterized by good stability, high sensitivity. At the same time,the method also had the advantage of near-IR region assay of little backgroundinterference. In part three, the tune action of Iron (Ⅲ) tetracarboxy phthalocyanine (FeC4Pc)–poly–lysine–nucleic acids equilibrium system on catalytic activity of FeC4Pc wasinvestigated. The oxidation reaction between hydrogen peroxide and DL-tyrosine in thepresence of FeC4Pc gave an intensive fluorescence emission. The fluorescence wasquenched by poly-lysine at its proper concentration due to its association with FeC4Pc andconsequently the descent of the catalytic activity of FeC4Pc, but recovered by addingnucleic acids. The study of mechanism showed that the electrostatic interac...