The Modulation Ofchitosan-dnainteraction By Different Concentrations And PH In Solution

Chitosan is a highly efficient,non-toxic gene therapy vector developed in recent years and has been widely used to prepare vectors.The electrostatic properties and morphology of chitosan-DNA complexes were studied by dynamic light scattering(DLS),magnetic tweezers(MT)and atomic force microscopy(AFM).When the concentration of chitosan is higher,it was found that the electrophoretic mobility of the DNA-chitosan complex was almost constant value when the pH of the solution was greater than the isoelectric point of chitosan(about 6.5).However,when the concentration of chitosan is lower,the electrophoretic mobility of the DNA-chitosan complex increases,reaching a maximum near the isoelectric point,and then decreases as the pH of the solution increases.In the magnetic tweezers experiment,at the same concentration of chitosan solution(0.02 mM),as the charge is neutralized,the condensing force between the DNA-chitosan complex increases first and then decreases with the increase of the pH value of the solution.This(DLS)measurement is consistent.This phenomenon may be related to the weak binding between DNA and chitosan in a low pH environment,and it has been verified by measuring the charge ratio of free chitosan to DNA complex in solution.At the same time,we observed various morphologies of DNA-chitosan complexes such as rings,rods,flowers,mites and other shapes were observed by AFM at different degrees of deacetylation,molecular weight and pH.