Lipopolycationic telomers for gene transfer: synthesis and evaluation of their in vitro transfection efficiency.

We report on the synthesis of a series of lipopolyamine telomers I-14,n, I-18,n, and II-18,n and on their in vitro gene-transfer capability. Their structure consists of a polyamine polar moiety, including n primary amine functions (from 1 to 70), connected to a hydrophobic moiety, including two hydrocarbon C14 or C18 chains, through a mercaptopropanoyl or mercaptoglyceryl unit and an amide or ether function. They were obtained by telomerization of N-[2-[(BOC)aminoethyl]]acrylamide with N,N-ditetradecyl- and N,N-dioctadecylpropanamide-3-thiol and rac-1,2-dioctadecyloxypropane-3-thiol, respectively, then BOC deprotection. For N/P ratios (N = number of telomer amine equivalents; P = number of DNA phosphates) from 0.8 to 10, these lipopolyamines condensed DNA, with or without the use of DOPE, forming lipopolyplexes or teloplexes of mean sizes less than 200 nm. Some trends, structure-activity and structure-toxicity relationships, were established to achieve both highest in vitro transfection levels and cell viability. Thus, DNA formulations based on telomers I-14,20 and I-18,20 and for N/P ratios lower than 5 led to the most efficient teloplex formulations for plasmid delivery to lung epithelial A549 cells.

Membrane permeability and stability of liposomes made from highly fluorinated double-chain phosphocholines derived from diaminopropanol, serine or ethanolamine.

The release of encapsulated carboxyfluorescein (CF) from liposomes made from various fluorinated amido-connected double-chain phosphocholines and their membrane permeability have been investigated at 37 degrees C in buffer and in human serum. These fluorinated membranes and liposomes display lower permeability coefficients and are able to retain more efficiently encapsulated CF than any of their respective conventional counterparts. Several of these liposomes are as effective as the first generation of liposomes based on fluorinated phosphatidylcholines, indicating that the chemical junction (ester/amide) and nature of the unit (glycerol, diaminopropanol, serine, ethanolamine) connecting the hydrophobic chains to the phosphocholine polar head have no significant effect on permeability and CF release. Our results show further that a fluorinated intramembrane layer reduces significantly the permeability of membranes in a liquid-crystalline state, protects the liposomes from the destabilizing effects of serum, and even increases their stability (in terms of dye retention) in serum when the membranes are in the gel state.