The transfection efficiency of calix[4]arene-based lipids: the role of the alkyl chain length

Abstract

The size, surface charge, and microstructure of lipoplexes comprising cationic lipids and nucleic acids are important factors for transfection efficiency. As these properties are largely determined by the cationic lipids used, a number of studies on the relationship between cationic lipids and the transfection efficiency have been reported. Among the many cationic lipids, lipids with multivalent cationic head groups are expected to be potent transfection reagents. Here, we prepared calix[4]arene-based lipids with different alkyl chain lengths from C3 to C15 and evaluated the relationship between the alkyl chain length and the transfection efficiency. C6 lipoplexes exhibited the highest transfection efficiency among all lipoplexes. The gene expression with C9 and C12 lipoplexes was slightly lower than that with C6 lipoplexes. C3 lipoplexes hardly induced gene expression, while C15 lipoplexes exhibited no complexation with plasmid DNA. Although all lipoplexes exhibited nearly identical characteristics, they exhibited different behaviours in terms of the interactions between the lipoplexes and anionic micelles comprising phosphatidylserine, a model of endosomal vehicle. After mixing with phosphatidylserine micelles, C6 lipoplexes released the bound plasmid DNA at pH 5 but not at pH 7, indicating that they can interact with the late endosomal membrane after being incorporated into cells. No plasmid DNA was released from C9 or C12 lipoplexes at either pH values. Thus, the alkyl chain length of cationic lipids is related to their interaction with the endosomal compartment and can provide a basis for the design of novel transfection reagents.

Amphiphilic Guanidinocalixarenes Inhibit Lipopolysaccharide (LPS)- and Lectin-Stimulated Toll-like Receptor 4 (TLR4) Signaling

“…The calixarene scaffold represents a very versatile structure to build amphiphilic compounds due to the possibility of variably and selectively functionalizing both its upper (aromatic para positions) and lower (phenolic oxygens) rim. Moreover, the possibility of linking to the macrocyclic platform several binding moieties, resulting in preorganized arrays, gives rise to systems that, exploiting a multivalent effect, frequently show improved biological activity with respect to corresponding monovalent models. , From this point of view, also the tight compaction of hydrophobic chains located at one of the rims can result in the enhancement of some properties such as (self)­assembling capabilities in an aqueous environment. − …”

Gene delivery based on macrocyclic amphiphiles

“…In 2015, Sakurai et al reported amphiphilic calix[4]arenes 64-68 with four amino groups at the upper rim and different lengths of alkyl chains at the lower rim. Highest transfection efficiency was observed with 65 that bears a medium-length alkyl chain with six carbons 84. Furthermore, in the presence of phosphatidylserine micelles, DNA can be released from the co-assemblies of 65 and plasmid DNA, at pH 5 but not at pH 7.…”

Biomedical Applications of Calixarenes: State of the Art and Perspectives

“…Sakurai studied the transfection efficiency of amino‐modified C4A‐based lipids with different alkyl chain lengths (C3–C15, 70 – 74 ), revealing that 71 lipoplexes exhibited the highest efficiency, 73 and 74 lipoplexes featured slightly lower efficiencies, while 70 and 74 lipoplexes were not active [132] . The 71 , 72 , and 73 lipoplexes also exhibited low cytotoxicity.…”