title: RNA and DNA association to zwitterionic and charged monolayers at the air-liquid interface.
abstract: The objective of this work is to establish under which conditions short RNA molecules (similar to miRNA) associate with zwitterionic phospholipids and how this differs from the association with cationic surfactants. We study how the base pairing (i.e., single stranded versus double stranded nucleic acids) and the length of the nucleic acid and the charge of the lipid/surfactant monolayer affect the association behavior. For this purpose, we study the adsorption of nucleic acids to monolayers composed of dipalmitoyl phosphatidylcholine (DPPC) or dioctadecyl-dimethyl-ammoniumbromide (DODAB) using the surface film balance, neutron reflectometry, and fluorescence microscopy. The monolayer studies with the surface film balance suggested that short single-stranded ssRNA associates with liquid expanded zwitterionic phospholipid monolayers, whereas less or no association is detected for double-stranded dsRNA and dsDNA. In order to quantify the interaction and to determine the location of the nucleic acid in the lipid/surfactant monolayer we performed neutron reflectometry measurements. It was shown that ssRNA adsorbs to and penetrates the liquid expanded monolayers, whereas there is no penetration of nucleic acids into the liquid condensed monolayer. No adsorption was detected for dsDNA to zwitterionic monolayers. On the basis of these results, we propose that the association is driven by the hydrophobic interactions between the exposed hydrophobic bases of the ssRNA and the hydrocarbon chains of the phospholipids. The addition of ssRNA also influences domain formation in the DPPC monolayer, leading to fractal-like interconnected domains. The experimental results are discussed in terms of the implication for biological processes and new leads for applications in medicine and biotechnology.
authors.affiliation: Division of Physical Chemistry, Center of Chemistry and Chemical Engineering, Lund University, P.O. Box 124, 22100 Lund, Sweden.
authors.forename: Agnes
authors.initials: A
authors.lastname: Michanek
authors.forename: Marianna
authors.initials: M
authors.lastname: Yanez
authors.forename: Hanna
authors.initials: H
authors.lastname: Wacklin
authors.forename: Arwel
authors.initials: A
authors.lastname: Hughes
authors.forename: Tommy
authors.initials: T
authors.lastname: Nylander
authors.forename: Emma
authors.initials: E
authors.lastname: Sparr
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D000327:Adsorption; D000388:Air; D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D008958:Models, Molecular; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012313:RNA / Q000737:chemistry*; D012330:RNA, Double-Stranded / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D000644:Quaternary Ammonium Compounds; D012330:RNA, Double-Stranded; D013501:Surface-Active Agents; C015831:dimethyldioctadecylammonium; D015060:1,2-Dipalmitoylphosphatidylcholine; D012313:RNA; D004247:DNA