The present invention provides polyplex comprising:(a) at least one polymer of formula (I) comprising at least one set of repeating units of formula:andwherein for each set of repeating units R1 represents either a hydrogen atom or a straight or branched chain alkyl group having from 1 to 20 carbon atoms and R2 represents a straight or branched chain alkyl group having from 1 to 20 carbon atoms,wherein n and m each represent an integer of from 1 to 5000,wherein the sum of n and m is from 10 to 250 when R1 represents a hydrogen atom and when the polymer of formula (I) contains only one set of repeating units and(b) at least one nucleic acid having improved transfection efficient and reduced cytotoxicity a method for preparing a polyplex a method for preparing the polymer of formula (I) for use in the polyplex a method for transferring at least one nucleic acid into a cell and a pharmaceutical composition comprising the polyplex and an adjuvant use of a polyplex or of a pharmaceutical composition according to the invention in transferring at least one nucleic acid into a cell and use of a polymer of formula (I) as defined above in transferring of at least one nucleic acid into a cell..To be accompanied when published by Figure 1 of the accompanying drawings.
