Studying The Effect Of Surfactant On The Spatial Structure Of DNA And Its Liquid Crystal State

The process of DNA compression and decompression plays a fundamental and important role in living organisms.It is an important research direction in molecular biology,genetics and medicine.In this paper,UV-Vis spectrophotometry,dynamic light scattering measurement,zeta potential measurement and AFM technique were used to study the compression-decompression process of DNA with different chain lengths induced by surfactants.CTAB was used to induce DNA compression and SDS or excess CTAB was used to induce DNA decompression.A DNA binding model was proposed by systematically studying the "compression-decompression" process of different DNA conformations.First,using several experimental methods to study together,when changing the molar ratio of CTAB to DNA,it was found that DNA molecules do not appear to be compressed only when the molar ratio QCTAB / QDNA is approximately equal to 1,as in the traditional sense,when the charge ratio is less than 1.Compression occurred and analysis revealed that the conformation of the DNA affected the charge ratio;Second,the state of the decompressed DNA molecule changes only in morphology,and the chemical structure remains almost unchanged.Moreover,the final state of the DNA molecule is determined by the electrostatic interaction between the DNA and the CTAB micelles and the in-chain repulsion,whether the CTAB alone or the DNA solution containing the SDS is added.Finally,a new binding model for DNA and CTAB compression is proposed to further investigate the process of DNA compression and decompression.All of these are helpful for understanding the biophysical mechanisms of DNA structural changes and have potential applications in biomedicine.DNA is a water-soluble molecule that dissolves in a buffer solution and is a colorless and transparent solution state.Under certain conditions,a thin film is formed.The liquid crystal structure of the DNA film has an important research value.We observed the DNA film with a polarizing microscope and observed that the DNA molecules were orientated in order and showed a certain crystal structure.The CCD was used to take different concentrations of DNA in different experimental environments and analyze the liquidcrystal structure.First of all,experiments have found that the higher the concentration of DNA,the easier it is to form bright-colored liquid crystal structures;secondly,temperature is also an important factor affecting the formation of liquid crystals;finally,when the external conditions are changed,cationic surfactants,metal cations,and other DNA interactions are added.And found some interesting liquid crystal structure.The preparation method of the DNA liquid crystal state thin film mentioned in this article provides accurate basic data and theoretical guidance for related research in the future,and the study of liquid crystal state structure also has certain help for gene detection and treatment.