Phosphonodithioester–Amine Coupling as a Key Reaction Step for the Design of Cationic Amphiphiles Used for Gene Delivery

A convergent synthesis of cationic amphiphilic compounds is reported here with the use of the phosphonodithioester–amine coupling (PAC) reaction. This versatile reaction occurs at room temperature without any catalyst, allowing binding of the lipid moiety to a polar head group. This strategy is illustrated with the use of two lipid units featuring either two oleyl chains or two-branched saturated lipid chains. The final cationic amphiphiles were evaluated as carriers for plasmid DNA delivery in four cell lines (A549, Calu3, CFBE and 16HBE) and were compared to standards (BSV36 and KLN47). These new amphiphilic derivatives, which were formulated with DOPE or DOPE-cholesterol as helper lipids, feature high transfection efficacies when associated with DOPE. The highest transfection efficacies were observed in the four cell lines at low charge ratios (CR = 0.7, 1 or 2). At these CRs, no toxic effects were detected. Altogether, this new synthesis scheme using the PAC reaction opens up new possibilities for investigating the effects of lipid or polar head groups on transfection efficacies.

Lipophilic Polyamines as Promising Components of Liposomal Gene Delivery Systems

Gene therapy requires an effective and safe delivery vehicle for nucleic acids. In the case of non-viral vehicles, including cationic liposomes, the structure of compounds composing them determines the efficiency a lot. Currently, cationic amphiphiles are the most frequently used compounds in liposomal formulations. In their structure, which is a combination of hydrophobic and cationic domains and includes spacer groups, each component contributes to the resulting delivery efficiency. This review focuses on polycationic and disulfide amphiphiles as prospective cationic amphiphiles for gene therapy and includes a discussion of the mutual influence of structural components.

Cationic amphiphiles based on malonic acid amides as transfection mediators

Objectives. The aim of this work is to synthesize cationic amphiphiles based on malonic acid amides. The target compounds should contain saturated and unsaturated alkyl chains in the hydrophobic portion, and one or two positive charges in the polar head as created by ethylenediamine and amino acid L-ornithine. For such cationic amphiphiles, we determined physicochemical properties and transfection efficiency of liposomes based on them.Methods. The initial compound in the synthesis is diethylmalonate. We used C-alkylation to add the first hydrophobic chain (with octylbromide, dodecylbromide, or octadecylbromide). N-oleylamine was used as the second hydrophobic chain, which was attached at the carboxyl group of the malonic acid via amide bond formation. The polar head was represented by ethylenediamine, which was then attached at the second carboxyl group of the malonic acid. Further, L-ornithine was attached to ethylenediamine to produce cationic lipids with two positive charges in the head group. The structures of the compounds were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, and elemental analysis. Particle size distribution was evaluated by photon correlation spectroscopy. The luciferase test was used to determine transfection efficiency using HeLa cells.Results. We have developed a synthesis scheme to produce new cationic amphiphiles with an asymmetric hydrophobic part. The obtained liposomal particles are approximately 120 nm in size and have a relatively high zeta potential of 29–30 mV.Conclusions. The size of these liposomes allows them to penetrate into cells, which makes it possible to use these compositions for transfection. The high zeta potential shows that the particles are stable. Our results demonstrate that the transfection efficiency of our liposomes (mixed with cholesterol) is comparable to a commercial formulation. Cationic amphiphiles based on malonic acid amides have great potential for liposome development for transfection.

Branched lipid chains to prepare cationic amphiphiles producing hexagonal aggregates: supramolecular behavior and application to gene delivery

Cationic amphiphiles featuring ramified lipid chains self-organized in water as inverted hexagonal aggregates. They demonstrated high gene delivery efficiencies.