Cyclen-based cationic lipids containing a pH-sensitive moiety as gene delivery vectors

Area of Science:

• Biomaterials Science
• Nanotechnology
• Gene Therapy

Background:

• Non-viral gene delivery vectors are crucial for therapeutic applications.
• Cationic lipids are widely explored for their ability to complex with DNA.
• pH-sensitive moieties can enhance endosomal escape for improved transfection.

Purpose of the Study:

• To design and synthesize novel cationic lipids based on 1,4,7,10-tetrazacyclododecane (cyclen) with imidazole groups.
• To evaluate the physicochemical properties, cytotoxicity, and in vitro gene transfection efficiency (TE) of the synthesized lipids.
• To investigate the role of the imidazole group and the effect of Ca(2+) on TE.

Main Methods:

• Synthesis of cyclen-imidazole based cationic lipids with varying aliphatic chains.
• Preparation of lipoplexes using 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE).
• Characterization of lipoplex size, zeta-potential, cytotoxicity (CCK-8 assay), and in vitro TE (eGFP and luciferase assays).
• Flow cytometry was used to assess cellular uptake.

Main Results:

• Lipoplexes exhibited good stability, nanosized particles (100-250 nm), and positive zeta-potential (+10-25 mV).
• Lower cytotoxicity compared to Lipofectamine 2000.
• Transfection efficiency was influenced by hydrophobic chain structure, with linoleyl chains yielding the best results.
• Imidazole-containing lipids showed significantly higher TE than imidazole-absent analogs.
• Ca(2+) addition enhanced TE by approximately 5-fold, attributed to improved cellular uptake.

Conclusions:

• Cyclen-imidazole based cationic lipids are effective non-viral gene delivery vectors.
• Lipid structure, particularly the imidazole group and hydrophobic chains, critically impacts gene delivery performance.
• Ca(2+) significantly enhances transfection efficiency by promoting cellular uptake.
• These novel lipids represent promising candidates for advanced gene therapy applications.