Liposome decoration via aminoalkyl nitrobenzene molecular gate triggers hypoxia-responsive cargo release

Although numerous anticancer agents are currently available, many still suffer from poor selectivity, resistance, tumor recurrence, and severe side effects. Liposomes have emerged as promising nanocarriers for anticancer drugs due to their biocompatibility and ability to be functionalized for selective release in the tumor microenvironment. In this study, hypoxia-responsive liposomes (HR-LPs) were designed by incorporating a novel molecular gate (MG) capable of contributing to disrupting the lipid bilayer under hypoxic conditions. This MG was integrated at different concentrations (10%, 15% and 20%) in the bilayer structure of liposomes loaded with a model molecule. These HR-LPs were synthesized using the thin-film hydration method and characterized in terms of size, polydispersity index, surface charge, and entrapment efficiency, providing optimal properties for drug delivery purposes. In vitro release studies were conducted using a Franz-diffusion cell setup under both normoxia and hypoxia conditions. Among the different formulations, only 15% HR-LPs showed a selective response to hypoxic conditions, with a significantly higher release rate and greater total amount of cargo released in the presence of nitroreductase (NTR), an enzyme overexpressed under hypoxic conditions, whereas conventional liposomes (CLPs) showed no significant differences between the tested conditions. Kinetic modelling indicated that cargo release involved both passive diffusion and relaxation processes, with MG incorporation increasing the contribution of the latter. These findings validate the developed manufacturing method and highlight 15% HR-LPs as a promising platform for further in vivo studies with antitumor agents, aiming to achieve controlled and targeted drug delivery in hypoxia-associated tumor environments.