Cationic Amphiphiles with Five-Membered Heterocyclic Linkers: Synthesis, Self-Assembly, and DNA Complexation Properties

Lipid-based nanoparticles are widely explored as non-viral vectors for nucleic acid delivery, where the molecular structure of cationic lipids strongly determines their performance. Five-membered heterocyclic linkers were explored as a new structural motif in cationic amphiphilic lipids for the development of promising gene delivery candidates. Novel lipids incorporating pyrrole, furan, and thiophene linkers were synthesized alongside structurally related aliphatic analogues, enabling systematic evaluation of how linker type influences physicochemical behavior and self-assembly properties. Self-assembly behavior in aqueous media was characterized by dynamic light scattering, and pDNA encapsulation efficiency was measured using the Quant-iT Pico-Green method. The resulting liposomes exhibited hydrodynamic diameters ranging from 92 to 1317 nm, while corresponding lipoplexes ranged from 302 to 1159 nm. Amphiphiles containing heterocyclic linkers demonstrated high pDNA encapsulation (>80% at optimal N/P ratios), whereas aliphatic analogues showed significantly reduced performance. These results demonstrate that linker structure strongly influences both self-assembly and nucleic acid binding properties. By evaluating structure–activity relationships, five-membered heterocycles are proposed as promising structural elements for the rational development of lipid-based gene delivery candidates.