Construction of CO2-responsive wormlike micelles from an aminoglycoside-based pseudo-pentameric surfactant for on-demand antimicrobial release.

CO2-responsive wormlike micelles are smart viscoelastic fluids with broad potential in oilfield stimulation and related fields. However, CO2-switchable systems constructed via the pseudo-surfactant strategy have so far been based mainly on flexible aliphatic polyamines, and the use of aminoglycoside antibiotics as multi-amine building blocks remains unexplored. Herein, we report the first construction of an aminoglycoside-based CO2-responsive pseudo-pentameric surfactant by simply mixing tobramycin-bearing five primary amine groups, a cyclohexose skeleton, and abundant hydroxyl groups-with stearic acid at a 1 : 5 molar ratio in aqueous solution. The resulting system forms highly viscoelastic wormlike micelles with a maximum zero-shear viscosity of ∼3200 mPa s. The system exhibits a lower overlap concentration (c* ≈ 75-85 mM) than the previously reported SA/cyclen pseudo-tetrameric system (c* ≈ 80-100 mM), which we attribute to the combined structural features of tobramycin-including its cyclohexose skeleton, abundant hydroxyl groups, and five primary amines. Moreover, antibacterial assays demonstrate that the wormlike architecture effectively shields tobramycin's activity, while CO2-triggered disassembly restores its full efficacy against Staphylococcus aureus. This work expands CO2-responsive wormlike micelles to aminoglycoside-based pseudo-surfactants and provides a dual-function smart fluid platform that integrates CO2-switchable viscoelasticity with on-demand antimicrobial release, opening avenues for applications ranging from wound dressings and antimicrobial coatings to oilfield biocides.