POLYMERS Vol.66 No.3
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DNA as a Functional Polymer
COVER STORY: Highlight Reviews
DNA Origami Takashi MORII
<Abstract> DNA origami is a simple and versatile method to design and construct defined 2-D and 3D shapes based on the fundamental base-pairing rule of DNA duplex formation, which opens a new dimension of design and functionalization of nanomaterials. Nano materials are created almost as you wish, and moreover, various other molecules are located one by one at defined addresses, namely at defined DNA sequences, with nanometer precision on the DNA origami structure. Possible application of DNA origami for scaffolding molecules is discussed.
Keywords: DNA Origami / Nanomaterials / DNA Nanotechnology / Proteins / DNA Binding Proteins / Tag-Proteins
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Unique Properties of DNA Brush Layers Formed on the Nanoparticles Surface Naoki KANAYAMA, Mizuo MAEDA
<Abstract> The properties of DNA strands immobilized at a solid-liquid interface have received considerable attention in fundamental and applied research, because they play key roles in various DNA-related functional devices, including biosensors. The formation of DNA brush layers on solid surfaces often results in restricted flexibility of the conformation of DNA strands due to crowding molecular packing (steric hindrance) and an aligned configuration of DNA on the surface. In addition, the local ionic environment (ionic strength, composition) surrounding the DNA brush layer affects the physicochemical characteristics of surface-immobilized DNA strands, yielding characteristics much different from those of free strands in solution. Here, we briefly introduce the unique properties of DNA brush layers formed on the nanoparticle surface including our recent works.
Keywords: DNA / Brush Layer / Nanoparticle / Melting Transition / Enzymatic Susceptibiity / Cellular Uptake / Dispersion Behavior / Surface Force
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Functions of Nucleic Acids with Non-canonical Structures : New Era of Post Watson-Crick Double Helix Naoki SUGIMOTO
<Abstract> Nucleic acids can adopt many types of non-canonical structures such as a triple helix and a quadruplex depending on the sequence and solution conditions. Recently, we developed a molecular crowding system which is the cell mimicking system to investigate thermodynamic behaviors of nucleic acids in cell. As results of our researches, the molecular crowding stabilizes the quadruplex with Hoogsteen base pairs, while it destabilizes the duplex with Watson-Crick base pairs. In this review, based on the thermodynamic results of DNA and RNA under the crowding condition, regulation of transcription and translation by the quadruplex structure of nucleic acids and its stabilizers is described. It is possible that the polymerase and ribosome bound to the template DNA and RNA, respectively, may mimic the crowded conditions in which we have shown to stabilize the quadruplex. Our results presented in this review indicate that stable non-canonical structures regulate transcription and translation. The results further our understanding of the transcription and translation processes involving the non-canonical structures and may guide the design of transcription and translation regulating drugs.
Keywords: Nucleic Acids / Molecular Crowding / Non-Watson-Crick Double Helix / Gene Expression / Bionanomaterial / New Drug
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COVER STORY: Topics and Products
Single-Stranded Oligonucleotide Hiroo IWATA
<Abstract> Single-stranded oligonucleotide-conjugated lipids (ssDNA-PEG-lipids) are composed of three parts with different functions. ssDNA has an adhesive capability via sequence-specific hybridization to complementary oligonucleotides. The other end lipid has nonspecifically anchoring capability into a lipid bilayer through the hydrophobic interaction. The middle PEG part give the conjugates water solubility and functions as a spacer between ssDNA and lipid. Such artificial tethers permit surface patterning of cells, controlled formation of cellular aggregates or immobilization of various molecules and nanoparticles on cells. In this topic, we briefly review interactions of the conjugates with cells, and their biomedical applications in cell arrays, cell therapies, tissue engineering.
Keywords: Single-Stranded Oligonucleotide / Hybridization / Lipid / Hydrophobic Interaction / Adhesion / Patterning
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Control of pDNA Packaging and Utility as Gene Delivery System Kensuke OSADA
<Abstract> Condensation of plasmid DNA (pDNA) was investigated using PEG-polycation block copolymer. pDNA was condensed into a rod-shaped structure within the spontaneously formed polyplex micelles, which obeyed a specific folding mechanism named “quantized folding scheme”. The folding number of pDNA, which alternatively meant the rod-length, was principally regulated by steric repulsive effect of PEG shell and inherent rigidity of DNA strands. The rod-shaped polyplex micelles exhibited potential functions as a systemic gene delivery system, presenting significant therapeutic outcomes in the mice model of pancreatic tumor. Besides the exploitation of such therapeutic potency, the condensation process of pDNA was investigated to pursue the principle of the DNA condensation. Eventually, precise modulation of interactive potency between pDNA and block copolymer process led to formation of either rod-shape, globule-shape and toroid-shape selectively, demonstrating controlled pDNA packaging.
Keywords: DNA Condensation / Polymeric Micelles / Block Copolymer / Gene Delivery System
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Physical Properties of a Solid Film of Deoxyribonucleic Acid Hisao MATSUNO, Keiji TANAKA
<Abstract> Promoting green innovation is an urgent priority. Effective utilization of natural resources excluding fossil fuels is one of the efforts that will contribute to the resolution of this issue. Here, we show that solid-state films made from deoxyribonucleic acid (DNA) can be used as a structural material. The great advantage of the DNA films over the ones made from synthetic polymers is that the mechanical properties are controllable, from glassy to rubbery, via semi-crystalline by simply regulating the water content in the film. In addition, the thermal molecular motion of the DNA film was examined by dynamic mechanical analysis. Four absorption peaks and one shoulder of the loss modulus were observed in the temperature domain from approximately 150 to 490 K. In order of increasing temperature, they were assigned to a BI to BII conformational transition, a relatively large-scale movement associated with water molecules, water evaporation, thermal denaturation of DNA, and a glass transition.
Keywords: Green Material / Deoxyribonucleic Acid (DNA) / Solid Film / Mechanical Property / Viscoelastic Property / Thermal Molecular Motion
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Polymer Science and I: A Personal Account
A Researcher after a Musician Tasuku NAKAJIMA
<Abstract> Nordic classical music, which is the author’s interest, has affected his life as a researcher. As he was fascinated with “nordic” music, he aimed to enter Hokkaido University located in the “northernmost” prefecture of Japan. At that place he met amazing gel science, and has been continuing gel research ever since.
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Front-Line Polymer Science
Biomaterial Properties Regulate Cell Adhesion Tomoyuki AZUMA, Madoka TAKAI
<Abstract> Biomaterials, which are used for the medical devices, should be biocompatible. Therefore, many researchers have enthusiastically evaluated the interaction between biomaterials and living system. The interaction between biomaterials and cells are not so clear, whereas that between biomaterials and proteins are rather revealed. Cells are much more complex than proteins and many parameters should be considered. The representative parameters, which could have some effects on the interaction between biomaterials and cells, are the surface chemistry, the surface topography and the mechanical property of biomaterials. Especially, the mechanical property have been recently focused on since that affects the stem cell lineage. Controlling cell lineage by the mechanical property will lead to the regenerative medicine. In this review, these three parameters are focused on to outline the interaction between biomaterials and cells.
Keywords: Cell Adhesion / Surface Chemistry / Topography / Mechanical Property
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