Properties And Functions Of Responsive DNA Complex Assemblies

Self-assembly with building block DNA has become a reliable approach to construct DNA complex assemblies via hierarchical self-assembly,which are the research hotspot in the field of physical chemistry,materials science and biomedicine science.We proposed a novel method for the construction of DNA complex materials through the ionic self-assembly of responsive assemblies with DNA.The responsive self-assembled materials include magneto-responsive fullerene,magneto-responsive Au assemblies and carbon quantum dots with fluorescence.External stimuli will be introduced to regulate the responsive assemblies and realize their application in drug delivery,detecting biomolecules and migration of DNA toward the magnetic field.The outline of this dissertation is as follows:In Chapter I:Introduction.From the structural specificity and functional responsiveness of DNA molecules,the advantages of DNA molecules as the building blocks of self-assemblies are summarized.The process of ionic self-assembly of DNA molecules with surfactants or with amphiphile-modified nano-materials was highlighted.We summarized the self-assembly mechanism,aggregation,and functional applications of DNA self-assembled materials.The effect of the physicochemical properties of DNA molecules on the morphology of hierarchical DNA assemblies was summarized,and the role of responsive functional groups in regulating the functions of DNA assemblies was elucidated.Finally,the main research contents and significance of this paper are summarized.In Chapter ?:Nonionic surfactant cannot compact DNA because of its low efficiency in neutralizing the negative charges of the phosphate groups of DNA.The purpose of DNA compaction using non-ionic surfactant-tetraethylene glycol monododecyl ether(C12EO4)was achieved by introducing Fe(III)as a "bridge" ion.We focused on the self-assembly behavior of C12EO4,Fe(III)and DNA,and further investigated the synergistic and competitive relationship through the steric repulsion of C12EO4 and DNA,the electrostatic interaction of Fe(III)and DNA,and the coordination of C12EO4 and Fe(III).This result provides theoretical support for the interaction between non-ionic surfactants and DNA.In Chapter III:We created the dual-responsive nanovehicle that can effectively combine and abundantly utilize magnetic and glutathione-reductive triggers to control the drug delivery and achieve more intelligent and powerful targeting.In the nanovehicles,paramagnetic fullerene/DNA complex ionic self-assembled with redox responsive hyaluronic acid(HA-SS-COOH).The introduction of HA-SS-COOH provided a response to a simulating reductive extra-tumoral environment by efficient cleavage of disulfide linkages by glutathione and site-specific drug delivery.We focused on the interaction mechanism of various building blocks in the aggregations.We have also given a rational explanation of the magnetic properties of the intelligent vehicle,as well as the relationship between magnetic behavior and assembly process of the magnetic surfactant.Because of their facile fabrication,rapid responsiveness to extra tumoral environment,and external automatic controllability by external magnet,the drug delivery nanovehicles constructed by magnetic fullerene-DNA/hyaluronic acid might be of great interest for making new functional nucleic-acid-based drug carriers,and also revolutionize the synthesis of magnetic assembled materials.In Chapter IV:In order to endow valuable responsiveness to self-assemblies of Au nanoparticles,the magnetic Au nano-assemblies were firstly prepared by using emulsion self-assembly of a magnetic surfactant.A versatile of morphology of magnetic Au nano-assemblies could be controlled by the counterions in surfactants including[CeCl3Br]-,[FeCl3Br]-and Br-as well as solvent.In particular,magnetic counterion[CeCl3Br]-,can induce self-grown of Au in emulsion self-assembly process and enhance the rigidity of magnetic Au scaffolds template.[CeCl3Br]-engaged Au/CTACe with fascinating capability of conglutination and targeted migration of DNA.Magnetic Au scaffold template can serve as a template scaffold to secondary self-assemble with DNA outside,producing smooth faced and hollow DNA nanocapsules.We believe that the creative magnetic DNA nanocapsules will extend the biological application field of Au assemblies.In Chapter ?:Fluorescence carbon quantum dots coordinated by Ce3+ ions(CQDCe)have been synthesized and exploited as building blocks to generate a series of hierarchical structures through the ionic self-assembly of CQDCe and biomolecules.In particular,vesicles can be constructed by the simple mixing of oppositely charged CQDCe and DNA in water.We focused on the formation mechanism of DNA vesicles.The self-assembly of CQDCe-biopolymers was accompanied by aggregation-induced photoluminescence quenching.The biosensing platform was designed to detect polypeptides and deoxyribonuclease I through competitive binding of CQDCe and enzymatic hydrolysis of the DNA backbone,respectively.We believe that the integrative self-assembly of CQDCe and DNA will enrich the theoretical study of vesicle formation by DNA molecules and extend the application of fluorescence carbon quantum dots in the biological field.