title: Complexation of lipofectamine and cholesterol-modified DNA sequences studied by single-molecule fluorescence techniques.
abstract: Lipoplex formation for normal and cholesterol-modified oligonucleotides is investigated by fluorescence correlation spectroscopy (FCS). To overcome the problems related to the fitting of autocorrelation curves when fluorescence bursts are present, the baseline fluorescence levels and the fluorescence bursts in the same trace were separately analyzed. This approach was not previously used in FCS studies of lipoplexes and allowed a more detailed characterization of this heterogeneous system. From the baseline levels, the number of free/bound DNA molecules and the presence of tens to hundreds of nanometer-sized lipoplexes were estimated using various mathematical models. Analysis of the fluorescent bursts provided an indication about the sizes of the lipoplexes, the number of DNA molecules in these aggregates, and the relative amount of lipids in each aggregate. An explanation for the higher transfection efficiency previously reported for one of the cholesterol-modified oligonucleotide compounds was found in relation to the formation of large size lipoplexes.
authors.affiliation: Laboratory of Photochemistry and Spectroscopy, Catholic University of Leuven, Celestijnenlaan 200F, Leuven, Belgium.
authors.forename: Anca
authors.initials: A
authors.lastname: Margineanu
authors.forename: Steven
authors.initials: S
authors.lastname: De Feyter
authors.forename: Sergey
authors.initials: S
authors.lastname: Melnikov
authors.forename: Damien
authors.initials: D
authors.lastname: Marchand
authors.forename: Arthur
authors.initials: A
authors.lastname: van Aerschot
authors.forename: Piet
authors.initials: P
authors.lastname: Herdewijn
authors.forename: Satoshi
authors.initials: S
authors.lastname: Habuchi
authors.forename: Frans C
authors.initials: FC
authors.lastname: De Schryver
authors.forename: Johan
authors.initials: J
authors.lastname: Hofkens
mesh_terms: D001483:Base Sequence; D002138:Calibration; D002784:Cholesterol / Q000737:chemistry*; D004247:DNA / Q000032:analysis* / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D009841:Oligonucleotides / Q000737:chemistry; D012235:Rhodamines / Q000737:chemistry
chemical_list: D008055:Lipids; C086724:Lipofectamine; D009841:Oligonucleotides; D012235:Rhodamines; C005358:tetramethylrhodamine; D004247:DNA; D002784:Cholesterol