Influence of Alkylisothiuronium Bromides and 7-Chloro-4,6-dinitrobenzofuroxan-5-olates on Liposome Key Properties

The ability of alkylisothiuronium bromides (C_nSUBr) and 7-chloro-4,6-dinitrobenzofuroxan-5-olates (C_nSUBf) to incorporate into lipid bilayer was assessed. It was established that the transition from the decyl to the hexadecyl homologue results in bilayer stabilization, as evidenced by an increase in the phase transition temperature of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine. Liposomes based on soy phosphatidylcholine and cholesterol were modified with representatives of both homologous series at various molar ratio of surfactant to lipid (1 : 50, 1 : 35, 1 : 20). The zeta potential of liposomes modified with C_nSUBr at all surfactant/lipid ratio was higher than that of liposomes modified with C_nSUBf. The liposomes were visualized using transmission electron microscopy. Hydrophilic substrate rhodamine B was successfully loaded into cationic liposomes with high encapsulation efficiency (over 89%). The most prolonged release of rhodamine B in vitro was observed from liposomes modified with C₁₆SUBr and C₁₆SUBf. Using the Korsmeyer–Peppas mathematical model, it was established that the release of rhodamine B from liposomes occurred through a mixed mechanism of substrate diffusion and destabilization of the phospholipid bilayer of liposomes.