Research Of Structure Directed Functions Of Self-assembled DNA Nanomaterials

DNA nanomaterials are self-assmmbled DNA nanostructures based on complementary pairs of DNA bases.With the cognition of DNA thermodynamics,we can precisely control the shape and size of DNA nanomaterials by rational design.DNA is the carrier of biological genetic information and almost exits in all of the organisms,so DNA nanostructures have good biocompatibility and non-toxic side effects with organisms.With the declined cost and improved quality of DNA synthesis,the advantages of DNA nanostructures had been applied in many areas of biomedical.However,the researchs based on DNA nanostructures are mostly focused on their structures,but not their genetic functions.The purpose of this paper is to explore the relationship between structure and biological function of programmable DNA nanonaterials.The results are divided into two parts.Part 1: The interation of the structure and genetic functions of DNA nanomaterials,including Chapter 2.Part 2: the interation of structure and biomedical functions of DNA nanomaterials,including third to fifth chapters.In the first part,the relationship between the structure and transcriptional activity of transcription template.It is found that the complete T7 promoter is a necessary for transcription,and the single strand or folded coding region of transcription template will not affect transcription.Based on this discovery,we prepared the traditional transcription template into dynamic DNA nanostructures and regulated transcription by structural transformation of T7 promoter on the transcription template.The second part consists of three chapters.For the third chapter,we prepared DNA nanostructures with different sizes based on DNA tetrahedron,and studied the relationship between structure size and celularl internalization.It was found that DNA nanostructures in larger sizes present more remarkable cellular internalization.The relationship between the size and immunostimulation of DNA nanostructures was studied with two different modes of administration.It was shown that DNA nanostructures in larger size displayed poor immunostimulation.In chapter 4,we inserted the restriction endonuclease BseGI recognition sequence at both ends of a single-stranded DNA,and designed it into a simple structure with stem-loop.The 100% phosphorylated single-stranded DNA was successfully achieved by structure induced BseGI digestion.In chapter 5,the structural integrity of DNA nanostructures after freeze drying was studied.It was proved that the integrity of DNA nanostructures could be maintained after freeze-drying at the appropriate Mg2+ concentration.Accelerated aging experiments further demonstrate that the dry powder DNA nanostructures are more stable than the ones in solution.