Novel Non-covalent Pyrene-based DNA Fluorescent Probe

Recognition and sensing of DNA is of paramount significant because increasing evidences show that various diseases are due to genetic disorders,and DNA measurement will be helpful for the diagnosis.Fluorescent DNA probes have been widely used in molecular biology and biochemistry studies.Traditional DNA probes,such as ethidium bromide,are usually used for the fluorescent staining of DNA.New fluorescent DNA probes were developed in recent years,such as Ruthenium polydiimine complex,TOTO and YOYO, etc.However,these DNA probes suffer from high price,time-consuming synthesis,low sensitivity,etc.To addressthese problems,it is necessary to develop new probes.In order to develop new DNA probes,we have synthesized two kinds of probes bipyrene ratiometric fluorescence probes and long wavelength Ruthenium polydiimine complex,the following work have been carried out:Fluorescent DNA probes with 1,6-hexanediyl as the linker between two pyrenes, phenylpyrenes or phenylethynyl pyrene fluorophores were synthesized(Py-1,Py-2 and Py-3) and their interactions with DNA were studied by UV-Vis absorption spectra,fluorescence spectra and viscosity measurements.The probes show red-shifted emission compared with pyrene(up to 20 nm).We found the binding of these probes with DNA can be either intercalation or groove binding.Ratiornetric fluorometry(ratio of the monomer and excimer emission intensity vs.concentration of DNA) was achieved with these probes for DNA quantification(with limit of detection,LOD,up to 0.1μg/mL).We also found that the undesired oxygen sensitivity of the emission intensity of pyrene fluorophore can be greatly suppressed by extending theπ-conjugation framework of pyrene(the I_Ar/I_Air value is decreased from 8.10 for pyrene to less than 2.20 for the DNA probes described herein).Probes Ru1-4 have been synthesized with different ligands.The "light-switch" character was achieved with these probes for DNA quantification.With binding to DNA,the emission intensity is enhanced by 1.23 folds compared to that of Ru-1 without DNA.And the fluorescence intensity of Ru-2 is 16.1 times that of the intensity of it without DNA.This is mainly due to that pyrene ligand has better planar and aromatic character than anthracene.We also found that for Ru-3 the undesired oxygen sensitivity of the emission intensity of Ruthenium complex can be greatly suppressed(the I_Ar/I_Air value is decreased to 1.2).