Detection Of Mirna By A Dumbbell Probe-based Rolling Circle Amplification And Synthesis And Properties Of Novel Porphyrin Derivatives

This thesis is composed of two parts : high sensitive isothermal detection of miRNA by a dumbbell DNA probe-based exponential rolling circle amplification and synthesis and properties of novel porphyrin derivatives.Ⅰ High sensitive isothermal detection of miRNA by a dumbbell DNA probe-based exponential rolling circle amplificationAberrant expression of some miRNAs is associated with cancer initiation,miRNAs have been regarded as a new therapeutic targets in cancer treatment.It is difficult to analyze the miRNAs because of their small size and sequence homology among family members,so,strategies for specific,especially sensitive quantitive detection of miRNAs have been the goal of scientists to explore.More recently,an isothermal amplification method,rolling circle amplification(RCA)has become increasingly popular in miRNA detection due to its simplicity,specificity,and high sensitivity.In this thesis,we propose a dumbbell DNA probe that integrates target-binding,amplification and signaling within one multifunctional design.With the exponential amplification,fluorescence signals can be sensitively detected with a remarkable sensitivity of 0.001 zmol,and the dynamic range is extremely large,covering 7 orders of magnitude.Moreover,RCA is an isothermal amplification technology that does not rely on expensive devices,which significantly reduces the cost of assays.Ⅱ Synthesis and properties of novel porphyrin derivativesDue to outstanding spectroscopy and electrochemical properties,porphyrin and its derivatives have wide application in catalysis,analytical chemistry,medicine,and chemsensor.Pyrene is a planar polycyclic aromatic hydrocarbons that have high fluorescence quantum efficiency and long fluorescence lifetime.It can easily form excimer in solution,which shows long wavelength fluorescence emission.Pyrene is often used as fluorophore for the synthesis of various fluorescent sensors.Although porphyrin and pyrene are widely used in various fields,there are few study combined the two together.Here we synthesized four novel pyrene porphyrin derivatives,the structure of all these compounds were characterized by mass spectra,IR spectra and1 HNMR.In addition,agarose electrophoreses was used to study the photo-cleavage of p BR322 plasmid DNA by a water soluble cationic porphyrin derivative i-TMPip EOPP.The results shows that i-TMPip EOPP exhibited good DNA photo-cleavage activities.The porphyrin had no DNA damage ability in dark,but was able to completely convert the supercoiled p BR322 DNA to nick DNA with the low concentration of 0.6μM under the irradiation,and the reaction obeyed the pseudo-first-order kinetics.The reactive oxygen species 1O2 and O2-generated in the reaction process maybe play a major role in the photo-cleavage reaction.i-TMPip EOPP shows higher photo-cleavage activity under acidic conditions,which makes it may be a promising anti-tumor PDT agent.