Abstract: The invention relates to compositions comprising double-stranded oligonucleotides of identical or different sequences and/or length, said oligonucleotides having sequences 3?N1N2 . . . Ni-1Ni . . . Nj5? wherein—3?Ni . . . Nj5? is half of a double-stranded 19-28mer oligonucleotide of sequence complementary to a target nucleic acid sequence present in a living cell, and—3?N1 . . . Ni-15? is a 3-50mer overhang of sequence allowing oligomerization of said double-stranded oligonucleotide. Compositions of transfection comprising said oligonucleotide compositions and there used for therapeutical application.

Abstract: The invention relates to a method for manipulating, isolating, detecting or amplifying a target nucleic acid in a sample by hybridization with an oligonucleotide-oligocation conjugate, comprising allowing said nucleic acid to react with an oligonucleotide-oligocation conjugate comprising at least A1 and Bj linked together directly or via a linker, wherein. A, is an i-mer oligonucleotides, with i=3 to 50, where Ai is an oligomer with naturally or non naturally occurring nucleobases and/or pentafuranosyl groups and/or native phosphodiester bonds, optionally comprising a marker group. Bj is a j-mer organic oligocation moiety, with j=1 to 50, where B is —HPO3—R1—(NH—R2)n—NH—R3—O—, where R1, R2 and R3 are lower alkylene, identical or different, NH—R2 moieties being identical or different when n is >1; HPO3—R1—CH(X)—R3—O—, where Ri and R3, identical or different, are lower alkylene and X is putrescine, spermidine or spermine residue.

Abstract: The invention relates to compositions of transfection comprising an oligonucleotide and an amphiphilic cationic molecule of formula (I) wherein, —X is N—R1, S or O, R1 being a C1-C4 alkyl radical or an hydroxylated C3-C6 alkyl radical, R2 and R3, identical or different, represent H or a C1-C4 alkyl radical, or R2 and R3 are linked together to form a saturated or unsaturated cycle or a heterocycle having 5 or 6 elements, E is a C1-C5 alkyl spacer, R4 and R5, identical or different, represent saturated or unsaturated, linear or branched, C10-C36 hydrocarbon or fluorocarbon chains, optionally comprising C3-C6 cycloalkyl, A? is a biocompatible anion. The invention relates to compositions active for oligonucleotides delivery into eukaryotic cells in culture, ex vivo or in vivo. The invention relates to compositions of transfection comprising an oligonucleotide active for RNA interference. Such compositions can be used as tools for biological studies or as drugs for therapies.

Abstract: The invention concerns a method of synthesising and preparing linear polyethylenimine (PEI) for use as a transfection vector, and the product obtained with such a method. It comprises drying a monomer 2-ethyl-2-oxazoline and polymerising said monomer for obtaining poly (2-ethyl-2-oxazoline) (PEOX) by: using acetonitrile as solvent, adding a dried initiator of the reaction of polymerisation, and mixing them altogether, purifying said obtained PEOX by evaporation, while performing at least three times successive washing/precipitation steps with methanol and diethyl ether and corresponding filtrations, in order to obtain (i), by performing 1H-NMR tests, correct identification of said PEOX polymer, confirmation of absence of monomer to a level <1.0% and confirmation of absence of solvent to a level <5.0% and (ii), by performing Gel Permeation Chromatography, a mean of molecular weight (Mw)>23,000 Da and polydispersity (Mw/Mn) of said PEOX<1.5, hydrolysing said PEOX.