Antibacterial activity and interfacial adsorption properties of quaternary-ammonium-salt-based gemini and trimeric surfactants

Quaternary-ammonium-salt-based surfactants are widely used as antibacterial agents and disinfectants. However, the factors affecting their antibacterial properties remain unclear. This study was aimed at investigating the relationship between antibacterial properties against Escherichia coli ( E. coli ) and Staphylococcus epidermidis ( S. epidermidis ) and wettability on polyethylene terephthalate (PET) surfaces. The analysis involved a quaternary-ammonium-salt-based gemini surfactant, and linear- and star-type trimeric surfactants. The gemini surfactant exhibited the highest antibacterial activities, likely due to its structural similarity to lipid molecules composing cell membranes. The linear-type trimeric surfactant exhibited higher antibacterial activity against E. coli than the star-type surfactant. Wettability analysis indicated that a correlation between increased surface adsorption on PET and enhanced antibacterial properties. Furthermore, the gemini and trimeric surfactants significantly inhibited S. epidermidis biofilm formation. This suggests that the strong interfacial adsorption of these surfactants, in addition to their ability to lower surface tension at the air/water interface, contributes to their antibiofilm properties. • Relationship between antibacterial properties and wettability was investigated. • Gemini and trimeric surfactants inhibit bacterial growth at low concentrations. • Linear-type trimeric surfactant shows higher antibacterial activity than star-type. • Saturated adsorption of surfactants leads to improved wettability on PET. • Mobility and dense adsorption of surfactants contribute to antibacterial activity.