The Study On Cationic Porphyrin As PDT Reagent And The Recognition Of Multiple DNA Structure

Photodynamic therapy(PDT)has attracted increasing interest as a promising and non-invasive method for cancer treatment.Double-stranded DNA(dsDNA)is one of the potential bio-targets in PDT,but G-quadruplex as bio-targets is rarely reported.So,it is much more important to searching the effective photosensitizers of G-quadruplex.Because of the special affinity of the tumor cell,porphyrins have became the significant photosensitizers.There were a large number of researches have reported the identification between porphyrin derivatives and G-quadruplex,but the research mainly involve the recognition of multiploidy G-quadruplexes and monoploid G-quadruplex,and the distinguish of different DNA structures were rarely to reported.In living cells,there are a large number of nucleic acids,protein,polysaccharide and other biological macromolecules.The presence of these substances have great influence on the result of the experiment.Therefore,to explore the identification of porphyrin derivatives and the DNA with different structure,molecular crowded conditions is necessary.The research contents of this thesis are as follows:1.Gel electrophoresis were used to study the phtotcleavage of water soluble cationic porphyrin TMPipEOPP and double-stranded DNA or telomerase Gquadruplex.In addition to that,standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetraazolium bromide(MTT)assay was used to estimate the cytotoxicity of TMPipEOPP.The results show that no DNA cleavage ability is observed for TMPipEOPP in dark,however,irradiation of sunlight can lead to the generation of 1O2,thus render TMPipEOPP with the ability to photocleave both dsDNA and G-quadruplex DNA.2.In order to further improve the of porphyrin derivatives and different DNA structures,we designed and synthesized another new cationic porphyrin derivative 5,10,15,20-tetra-{4-[2-(1-methyl-1-pyrrolidine)ethoxy]phenyl}porphyrin(TMPyrEO PP).The ructure of TMPyr EOPP has been characterized and the result demonstrated it has synthesized pure objective product.3.Using UV-vis spectroscopy,fluorescence spectroscopy and circular dichroism,we research the specific recognition of TMPyrEOPP to double-stranded DNA,single-stranded DNA and G-quadruplex in crowded conditions under the different pH value(Na2HPO4-NaH2PO4 buffer solution).The result showed that under different pH there were big difference about the specific identification of TMPyr EOPP to double-stranded DNA,single-stranded DNA and G-quadruplex.Along with the change of pH value TMPyrEOPP also could perfectly discriminate multiploidy G-quadruplexes from duplex,single-stranded and monoploid G-quadruplex DNAs under molecular crowding conditions.