Optimized Solid-Phase-Assisted Synthesis of Oleic Acid Containing siRNA Nanocarriers

Area of Science:

• Biomaterials science
• Oligonucleotide delivery systems
• Chemical synthesis

Background:

• Cationic lipo-oligomers are effective siRNA carriers due to polyplex formation and endosomal escape.
• Solid-phase synthesis allows for sequence-defined lipo-oligomer production.
• Trifluoroacetic acid (TFA) cleavage can lead to oleic acid modification, forming undesired adducts.

Purpose of the Study:

• To optimize the synthesis of cationic lipo-oligomers containing oleic acid for siRNA delivery.
• To investigate the impact of oleic acid modification on lipo-oligomer performance.
• To compare the efficacy and safety of lipo-oligomers with intact oleic acid versus modified hydrophobic moieties.

Main Methods:

• Solid-phase-supported synthesis of sequence-defined lipo-oligomers.
• Optimization of trifluoroacetic acid (TFA)-mediated cleavage to minimize side product formation.
• Comparative analysis of lipo-oligomers containing oleic acid (C18:1), stearic acid (C18:0), hydroxystearic acid, and 8-nonanamidooctanoic acid.
• Evaluation of pH-dependent lytic activity, gene silencing efficiency, and cell tolerability.

Main Results:

• Optimized cleavage protocol significantly reduced TFA adducts in oleic acid-containing lipo-oligomers.
• Lipo-oligomers with intact oleic acid demonstrated favorable pH-dependent lytic activity.
• The oleic acid-containing structure exhibited superior gene silencing efficacy compared to saturated or modified analogs.
• Excellent cell tolerability was observed for the lipo-oligomer featuring intact oleic acid.

Conclusions:

• Optimized synthesis yields high-purity cationic lipo-oligomers with intact oleic acid.
• Oleic acid-containing lipo-oligomers are superior siRNA carriers, offering enhanced gene silencing and cell compatibility.
• These findings highlight the importance of preserving the unsaturated nature of oleic acid for optimal siRNA delivery system performance.