Preparation And Characterization Of The Polymer Film On DNA Origami Surface

DNA origami is a biological material that is composed of DNA and it can forme nanometer-scale arbitrary 3D shapes by complementary hybridization of DNA strands.DNA origami is prepared by folding of a large circular single strand DNA(e.g.M13mp18)using a number of short complementary DNA single strands.However,the stability of DNA origami has to be improved to adapt to more application conditions.At present,the solution to the stability of DNA origami mostly uses positively charged substances to interact with the DNA origami structure through electrostatic adsorption,thereby achieving the purpose of stabilizing the DNA origami structure.However,the way of stabilizing DNA origami by electrostatic adsorption is susceptible to interference from other strongly charged substances in the environment.Therefore,this thesis investigated a method to prepare the polymer thin film on DNA origami by free radical polymerization with DNA intercalating monomers.The DNA origami structure modified by the polymer thin film is more stable,is no longer affected by other environmental factors,and has surface properties different from the original DNA structure.The thesis includes two parts:1.M13mp18 extraction and DNA origami constructionThe first part begins with the preparation of single stranded M13mp18 DNA.This was done by transfection of double-stranded M13mp18 into competent E.Coli cells to allow amplification of M13 phage,and extraction of M13mp18 single strand circular DNA from M13 phage.Through continuously improved experimental methods,the extaction yield was significantly improved.The self-extracted M13mp18,which synthesizes two-dimensional and three-dimensional DNA origami structures,was also characterized,and the integrity of the M13mp18 sequence was also determined.The self-designed three-dimensional DNA origami solves the experimental problems of DNA origami from design,synthesis to characterization.2.Preparation of polymeric film on DNA origamiA polymer monomer-PyMMA that was synthesized can intercalate into DNA double strands,and PyMMA was embedded in DNA origami.Because PyMMA carries a C=C double bond,after adding initiator,crosslinker and other monomers,DNA origami can undergo surface free radical polymerization,A thinner polymer film on the surface of the DNA origami is obtained by changing the initiator concentration,reaction time,monomer type and monomer concentration.The presence of the polymer film was determined by the height statistics before and after the polymerization of the DNA origami surface and the observation of the nanoIR on the surface of the DNA origami.In this thesis,a polymer film with a thickness of about 0.5 nm is formed on the surface of the DNA origami.While maintaining the shape of the DNA origami,provides another way for the surface modification of the DNA origami.The introduction of the polymer film changes the surface properties of the DNA origami and protects the DNA origami to a certain extent.