The Study Of DNA Nanostructures As Drug Delivery Carriers

Purpose:The development of nanotechnology,clinical biomarker and related ligand have promoted the researches about intelligent and precious drug delivery and have advanced the cancer gene therapy in a significant degree.Several nano drug delivery systems such as liposomes and macromolecule nanoparticles have been approved for clinical application,but the clinical efficienty of these systems has not yet been particularly revealed.More researches and insights of nano drug delivery vehicles that are novel,biocompatible and multi-functional are critical for the application of nanotechnology in drug delivery area.DNA exists widely in organisms as the genetic material.DNA nanostructures,as a kind of promising drug delivery tools,have their inherent edges,including precise self-assembly,controllable structure,good biocompatibility.They also can be used for pinpoint modifications of drugs,fluorescent molecules,mi RNAs and si RNAs,which opens a novel path to build the drug delivery system based on nanocarriers.Methods:1.The 6-helix DNA nanotube with Cy3-and Cy5 double fluorescent label was constructed,in which four of extending strands can pair with micro RNA-21 thus to trigger the open of the nanotube.Human melanoma cells were cultured with these nanotubes.The change of Cy5 fluorescence intensities and locations of DNA nanostructures in cells were observed by a laser scanning confocal microscope in different time intervals.2.A self-fluorescent molecule combining with 6-helix DNA nanotube and the organic fluorophore DFHBI-AE was designed.And the fluorescence was stablized by a G-quadruplex,a DNA double helix and the chemical bonds between the organic fluorophore and bases.The fluorescence intensity of the nanotube in open and closes states were measured using a fluorescence spectrophotometer respectively.3.The specially designed tetrahedron-peptide,tetrahedron-peptide-CpG(I),tetrahedron-peptide-CpG(II)were injected into mice,and the concentration of IL-6 were measured in mice serum by ELISA.Results:1.Cy3 fluorescence was observed in the cytoplasm of human melanoma cells after three hours incubation;Cy5 fluorescence can be observed in 6 hours and it was gradually enhanced from 7 to 9 hours;The Cy5 and Cy3 fluorescence were similar in brightness in 10 hours.2.The fluorescence intensity was 800 a.u.exciting at 350 nm when the DFHBI-AE stablize.The fluorescence intensity changed to 300 a.u.when nanotubes opening density of 300 a.u or so.3.The concentrations of IL-6 produced by the three trahedral structures were9.238 pg/m L,17.150 pg/m L and 8.665 pg/m L respectively.Conclusion:1.The designed DNA double-fluorescent nanotubes can enter human melanoma cells,recognize the mi RNA-21 and gradually opens to make Cy5 fluorescence recovers.Can be used as a drug-targeted delivery vehicle and can control drugs’ sustained release.2.Through opening and closing of nanotubes,the fluorescence can be generated.3.The tetrahedron was used as a carrier to link Melan-A antigen peptides and different numbers of CpGs,which was injected into C57 mice for the further serum cytokines detection.CpG enhanced the immune reactivity of Melan-A antigen peptide,and the efficiency is dependent on the number of CpG.