Self-assembled Materials Containing Complementary Nucleobase Molecular Recognition
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1094-DD06-05
Self-assembled Materials Containing Complementary Nucleobase Molecular Recognition Wirasak Smitthipong1,2, Arkadiusz Chworos3, Brian Lin4, Thorsten Neumann1,4, Surekha Gajria4, Luc Jaeger1,4, and Matthew Tirrell1,2 1 Materials Research Laboratory, University of California, Santa Barbara, CA, 93106 2 College of Engineering, University of California, Santa Barbara, CA, 93106 3 Department of Physics, University of California, Santa Barbara, CA, 93106 4 Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106 ABSTRACT Here we report the nucleic acid/cationic amphiphile based-materials in which we exchange the counter-ions of the polyanionic backbone of the nucleic acids with the cationic amphiphiles to form self-assembled transparent films with the thickness of several microns. Predominantly, single stranded poly(A), poly(U) and double stranded poly(AU) were employed for these studies. Small-angle X-ray scattering (SAXS) experiments suggested lamellar-like structure for all the film samples. However, the molecule length as well as the molecular structure of nucleic acids can affect the topology and mechanical properties of these films. Complementary base-paring of poly(AU) is reported here with comparison to poly(A) and poly(U) complexes.
INTRODUCTION Self-assembly is one of the most important processes which govern functional biological structures in nature. Such interactions are important in the fields of the materials that can imply molecular recognition, directionality, addressability and programmability of the supramolecular character [1,2]. Nucleic acids are example of molecules that are able to self-assemble into supramolecular architectures through the formation of specific hydrogen bonds between complementary nucleobases [3,4]. Another example observed in nature, is the glycocalyx, typically of polysaccharide origin. The glycocalyx consists of negatively charged macromolecules that can be embedded into a cell membrane or other positively charged lipid bilayer [5]. Mimicking this strategy leads to bottom-up design; for example, the supramolecular assemblies between DNA and cationic liposomes in the aqueous environment could be used in the gene delivery mechanism [6] and DNA/RNA-lipid films could be potentially engineered as an antibacterial material [7]. Achieving both the proper biofunctionality and desired structural properties are challenges for development of such biomaterials. Our goal was to develop a technique in which nucleic acids are used as functional materials. To achieve this, we modified nucleic acids in such a way that they become soluble only in organic solvent so that they can be used in film preparation process. The complexes are formed through the electrostatic interaction between the polyanionic nucleic acid backbone and cationic amphiphile. Furthermore, hydrophobic interaction between two surfactant layers facilitates formation of multi-lamellar films. We optimized this method to be able to prepare not only DNA or RNA films but also to prepa
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