title: Associating oligonucleotides with positively charged liposomes.
abstract: Oligonucleotides (ODNs) are short (up to 30 bases) fragments of single-stranded nucleic acids that are used as sequence specific regulators of gene expression and anti-sense based therapeutics. ODNs are frequently aggregated with particulates in order to improve their pharmacological characteristics. Complexes of ODN and lipid aggregates are among the most commonly mentioned in the literature. In order to control the formation and final properties of such aggregates, a detailed description of how ODN interacts with the lipid surface is needed. In this paper, we present the results of fluorescence measurements regarded an association of 20 base ODN, labelled with fluorescein, and a lipid surface containing various amount of positive charge. Unilamellar lipid vesicles were formed from egg phosphatidylcholine (PC) and various amounts of the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). It was found that about 20 mol% of DOTAP in the lipid bilayer suffices to obtain complete ODN association. This result was further confirmed via measurements performed by fluorescence correlation spectroscopy (FCS). These in turn showed that the diffusion time of labelled ODN in the presence of cationic liposomes decreases. Also, the particle number and count rate were reduced, concurring with conclusions derived from steady-state fluorescence spectroscopy results.
authors.affiliation: Institute of Physics, Wrocław University of Technology, Wybrzeze Wyspiańskiego 27, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Jurkiewicz
authors.forename: Andrzej
authors.initials: A
authors.lastname: Okruszek
authors.forename: Martin
authors.initials: M
authors.lastname: Hof
authors.forename: Marek
authors.initials: M
authors.lastname: Langner
mesh_terms: D001483:Base Sequence; D004058:Diffusion; D004563:Electrochemistry; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry; D019793:Fluorescein / Q000737:chemistry; D066298:In Vitro Techniques; D008081:Liposomes / Q000737:chemistry*; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D005229:Fatty Acids, Monounsaturated; D008081:Liposomes; D009838:Oligodeoxyribonucleotides; D000644:Quaternary Ammonium Compounds; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane; D019793:Fluorescein