α-Tocopherol-based cationic amphiphiles with a novel pH sensitive hybrid linker for gene delivery

Abstract

Endosomal escape is one of the barriers for the efficient liposomal gene delivery. To address this and based on earlier encouraging results using tocopherol cationic lipids, we elaborated chemical modifications on tocopherol cationic lipids by introducing a novel hybrid pH sensitive linker "ether-β-hydroxy-triazole" between tocopherol, the anchoring moiety and the basic tris(2-hydroxy ethyl)quaternary ammonium head group (Lp2). As control lipids we designed two lipids (Lp1 and Lp3), one is with only the ether-β-hydroxy linker in between α-tocopherol and quaternary tris(2-hydroxyethyl)ammonium (Lp1) and the other is with the same novel hybrid linker i.e. "ether-β-hydroxy-triazole" between the α-tocopherol linked and quaternary tris-ethyl ammonium head group (Lp3). Liposomes were formulated with a combination of a well-known co-lipid, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and biophysical characteristics such as DNA binding, hydrodynamic diameters and global surface charges for liposomes and lipoplexes of respective lipids were evaluated. Cell viability assay and in vitro transfection studies were carried out in NIH3 T3, B16F10, HEK-293, and HepG2 cell lines. In vitro transfection data for the liposomes of lipids (Lp1, Lp2 and Lp3) revealed that the Lp2 lipid with a novel hybrid pH sensitive linker showed superior transfection efficiency when compared with the remaining two analogues. More importantly, Lp2 has shown a similar pattern of transfection efficiency in HepG2 and HEK-293 cell lines when compared with commercially available Lipofectamine 3000.

Cationic lipids for gene delivery: many players, one goal

“…Recently, in order to improve the overall biocompatibility of α-tocopherol-based cationic amphiphiles, Patri's group used ether-β-hydroxy-triazole linker that underwent total hydrolysis at the endolysosomal pH. This resulted in the endosomal escape of NAs that, in turn, gave rise to transfection efficiencies similar to that of Lipofectamine 3000 and very low cytotoxicity (Muripiti et al, 2018).…”

Further Studies on Cationic Gemini Amphiphiles as Carriers for Gene Delivery─The Effect of Linkers in the Structure and Other Factors Affecting the Transfection Efficacy of These Amphiphiles

“…Transfection efficacy is a function of many factors such as the structure of the GAs having different hydrophobic groups, head groups, and spacers, , use of different types of helper lipids to prepare liposomes, the ratio of the GA to DNA concentration (i.e., the N/P ratio), size and zeta potential of the lipoplexes, and the type of cell lines used for their in vitro evaluation. Serine-based cationic gemini surfactants with different alkyl chain lengths, and amine/amide or ester groups as spacers/linkers offered good binding to the DNA molecules with efficient in vitro transfection property and high cell viability.…”

Review of Zinc(II) Scaffolds: Efficient Role in Gene Delivery

“…Generally, there exists a strong electrostatic interaction between the anionic phosphate backbone of deoxyribonucleic acid (DNA) and cationic part of lipid that affects the higher cellular uptake of the gene. [4][5][6][7] However, there is a problem with cationic lipids that, the highly positive surface charges can induce non-specific binding to the components of blood and may lead to less-transport efficacy and high toxicity. In this regard, to overcome the above anomalies, Zn(II)-coordinated cationic lipids are widely investigated and are expected to become ideal carriers for the gene delivery system (GDS) owing to their favourable bio-compatibilities and their sole structures.…”

“…From the recent past, cationic lipids are also emerged as a new choice and extensively have been using as vectors (vehicles) in order to replace the novel gene in place of such a defective gene. Generally, there exists a strong electrostatic interaction between the anionic phosphate backbone of deoxyribonucleic acid (DNA) and cationic part of lipid that affects the higher cellular uptake of the gene . However, there is a problem with cationic lipids that, the highly positive surface charges can induce non‐specific binding to the components of blood and may lead to less‐transport efficacy and high toxicity.…”