Study On The Binding Mode Of Phenanthrene And Chrysene With DNA In Vitro

In this paper,a variety of research techniques were used to explore the binding mode and binding ability of phenanthrene(PHE)and chrysene(CHR)with herring sperm DNA in vitro,respectively.The influence of environmental factors such as temperature,p H,and coexistence environment on the interaction of CHR with DNA was further analyzed.Finally,the above environmental factors were applied to the preliminary exploration of DNA captured and eliminated the CHR.The aim of this paper is to establish a new way to remove PAHs by DNA.The specific results were as follows:(1)UV-vis spectra showed that both PHE and CHR interacted with DNA,leading to the changes of DNA structure,which was manifested by that the addition of PHE and CHR increased the melting temperature of DNA by 8.0℃ and 12.7℃,respectively,indicating that intercalation occurred in the system.The intensity fluctuation of CD characteristic negative and positive peaks indicated that PHE and CHR all intercalated with DNA.Fluorescence microscopic observation showed that the changes of fluorescence spots of PHE and CHR on the magnetic beads were similar to the changes of EB,which further intuitively confirmed the intercalation mode of PHE and CHR with DNA.The results of fluorescence spectra showed that the addition of DNA caused the static fluorescence quenching of PHE and CHR,which indicated that PHE and CHR formed stable complex with DNA.Van der Waals force and hydrogen bond played a main role in the process of complex formation.The negative Gibbs free energy indicated that the interaction of PHE and CHR with DNA was spontaneous in vitro.In conclusion,it could be inferred that both PHE and CHR interacted with DNA in an intercalation mode,(2)The DNA binding saturation values of PHE and CHR were calculated by resonance light scattering spectra,which were 0.76 and 0.84 respectively.The ability of CHR bound with DNA was greater than that of PHE.Taking CHR as the research object,the optimal interaction conditions were obtained: 30℃,p H 7.40,and the DNA binding saturation value of CHR reached 0.94.Based on the optimal conditions,the DNA binding saturation values decreased after the addition of sodium chloride and calcium chloride.However,the DNA binding saturation values increased in different degrees respectively with the addition of glucose,vitamin C,lysine,leucine,urea and sodium dodecyl sulfonate.(3)When the amount of DNA was 0.74 μg and the initial concentration of CHR was5.52 × 10 mol/L,the removal rate of CHR could reach 93.97%.And with the addition of the environmental co-existence mentioned to CHR-DNA,the removal rates of CHR were respectively 92.23%,89.56%,95.22%,94.81%,94.71%,94.34%,94.31%,and94.06%.The presence of sodium chloride and calcium chloride could hinder the removal of CHR.However,the presence of other environmental coexisting substances could promote the removal of CHR.The magnetic beads used in the experiment were reused for three times,and the removal effect was still good,indicating the stable performance of the magnetic beads used in the experiment.In conclusion,interaction of PHE and CHR with DNA in vitro was intercalation,and the binding ability of CHR to DNA was greater.Taking CHR as the experimental object,after optimizing the environmental conditions for the interaction between CHR and DNA,the removal of CHR also showed a promoting effect.The results of this study could provide a reference for the future research of using DNA to selectively bind and remove PAHs.