Composites of malonic acid diamides and phospholipids – Structural parameters for optimal transfection efficiency in A549 cells

Abstract

The aggregation behavior of various zwitterionic helper phospholipids, such as DOPE, DOPC, and DPPC, in combination with two new cationic lipids, namely TH4 and OH4 (second generation of malonic acid diamides) in different molar ratios was studied with regard to their physical–chemical properties. Additionally, lipoplexes prepared from these lipid mixtures were characterized with respect to the transfection efficacy using an EGFP‐assay. The lipid mixtures with the fluid cationic lipid OH4 and DOPE have shown comparable transfection efficiency with Lipofectamine 2000®. Furthermore, this report demonstrates the huge influence of the helper lipid on the transfection efficiency. Thereby, alkyl chain fluidity, lipid miscibility and charge density have an important influence on an efficient gene transfer. Practical applications: Although lipofection is a topic of gene therapy since 1989, finding an effective lipid system with new cationic lipids is still a process of trial and error. There is much unknown about the process of lipoplex formation as well as the release of the genetic cargo. Aim of the presented work is to find physical–chemical parameters which are connected with an effective gene transfer. This report demonstrates the influence of the cationic and helper lipid on the transfection efficiency. Thereby, alkyl chain fluidity, lipid miscibility and charge density have an important influence on an efficient gene transfer.

Phenylene bolaamphiphiles: Influence of the substitution pattern on the aggregation behavior and the miscibility with classical phospholipids

“…It could also be possible that within these lipid disks a partial separation of both components occurs and that the bolaamphiphile molecules are accumulated at the rim of the bilayer disks stabilizing them against fusion into larger aggregates. Comparable disk-like assemblies, which are often called bicelles, were also observed for various phospholipid mixtures as well as mixtures of phospholipids with other amphiphiles, e.g., in DPPC/DHPC systems [38] that are used as skin delivery systems [39], in PEG-stabilized bilayer disks [40,41], in phospholipids with membrane scaffold proteins [42,43], for DPPC in combination with a T-shaped amphiphilic molecule [44], or for DPPC in mixture with cationic lipids [45] that are used for gene transfection.…”

Lamellar versus Micellar Structures—Aggregation Behavior of a Three‐Chain Cationic Lipid Designed for Nonviral Polynucleotide Transfer

“…Figure 8shows the gene transfer efficiency and cell viability in the presence and absence of serum determinedb yE GFP assay and AlamarBlue assay,r espectively. [15] The transfection efficiency increases with increasing N/P ratio (increasing amount of lipid), whereas the cell viability decreases. The most effective of the lipoplex compositions investigated exhibit ap ositive zpotential( compareF igures 7b and 8) and exhibit N/P ratios above the point of total DNA complexation (compare Figure-s7aa nd 8).…”

“…The lipid used in this work belongs to the class of malonic acid diamideso ft he second generation described previously. [15][16][17] The lipid was synthesized from precursor A, precursor B, and tris(2-aminoethyl)amine using synthesisp rocedures described earlier( Scheme 1). [17] DiTT4 has three alkyl chains (lipophilic moieties).…”

“…The areas determined from the isotherms were A O = 97 2 (pH 5), 92 2 (pH 7.3), and 67 2 (pH 10). For V of approximately 376.9 3 and l C = 16.27 for atetradecyl chain in an all-trans conformation (ideal situation), [15] the following P valuesw ere determined:0 .72 (pH 5), 0.73 (pH 7.3), and 1.04 (pH 10). Therefore, lamellar (P = 0.5-1) and inverse hexagonal (P > 1) mesophases are expected, [26] considering that gauche conformers in the alkyl chains result in larger P values.…”

“…The procedures are described in recently published work. [15] The experiments were performed with lipid formulations prepared as described above.…”