Glycine linker modulates the tunable self-assembly and antibacterial efficacy of octanoyl lipopeptides

The linker region of lipopeptides has demonstrated considerable potential in modulating their antibacterial activity. However, a clear consensus regarding the influence of link length on their physicochemical properties and biological activities remains elusive. To address this, we designed a series of octanoyl lipopeptides, C₈G_n(VVKK)₂V-NH₂ (n = 1-3), with varying glycine linker length. Altering the linker length led to distinct physicochemical properties and self-assembly behaviors, enabling an investigation into the structure-property-function relationship. Among the series, C₈G(VVKK)₂V-NH₂ exhibited the lowest surface activity and consequently the weakest antibacterial efficacy. In contrast, C₈G₂(VVKK)₂V-NH₂ and C₈G₃(VVKK)₂V-NH₂ displayed high surface activity, and self-assembled into micelles above their critical aggregation concentrations (CACs). Notably, these micelles disassembled upon dilution, facilitating high antibacterial activity through bacterial membrane disruption. Conversely, the micelles formed by C₈G(VVKK)₂V-NH₂ were exceptionally stable, allowing them to attach on bacterial surface but not permeate bacterial membrane, leading to low antibacterial activity. Thus, we demonstrate that the incorporating glycine linkers modulates the self-assembly behavior of octanoyl lipopeptides: increased linker length promotes micelle disassembly and enhances antibacterial activity. This study offers deeper insights into the antibacterial mechanisms of self-assembling lipopeptides, facilitating the future exploration of their biomedical applications.