DNA Chemical Modification And Application Based On Substitution Reaction

Compared with protein,natural DNA provides less chemical diversity,which limits its versatility and applicability.Chemically modification is helpful to improve the physical and chemical properties of nucleic acid and broaden its application.Existing DNA chemical modification methods include Stille coupling reaction,Buchwald-Hartwig reaction,Diels-Alder reaction,thiol addition,azide alkyne cycloaddition and so on.There are many deficiencies,such as complicated operation,low yield and high cost,which limit the application of DNA in gene function analysis,biological analysis,disease diagnosis and treatment.To solve the above problems,this paper innovatively proposed a new simple,efficient,cheap and universal DNA chemical modification method based on the substitution reaction between phosphorothioate DNA and halogenated hydrocarbon.The main research contents are as follows:First,DNA was quickly prepared by solid-phase phosphoramide method,which has high coupling efficiency,short reaction period,stable initial reactants and intermediate materials.During the reaction,all reagents and solvents flow through the controlled pore glass.Excess liquid reagents or by-products can be removed by filtration,and no purification is required between cycles.It only takes a few hours to synthesize DNA of any sequence,which provides a material basis for the subsequent nucleic acid research.Secondly,the experiments verified the feasibility of DNA chemical modification methods based on substitution reactions.DNA modified with different numbers of phenylpropyl groups and different types of organic groups were synthesized by this method,and their structures were identified by mass spectrometry.In addition,the modification positio,modification quantity and the distance between the modification groups of the organic group on the DNA chain can be controlled by adjusting the modification position and amount of phosphorothioate.Finally,we successfully synthesized 15 hydrophobic group-modified DNA by means of this DNA modification method.The influence of hydrophobic groups on the bingding affinity of DNA and protein was investigated by changing the modification type,modification position and modification quantity of hydrophobic groups.DNA modified by hydrophobic groups has different affinity with different proteins,which is expected to be used as a biosensor for early diagnosis and clinical detection of diseases.