Interactions between biocidal surfactants and bacterial membrane mimics: a NR study at the air-water interface

Quaternary ammonium compounds (QACs) have high inhibitory and bactericidal activity against pathogenic microbes and their toxicity has been found to depend upon their structure. However, no simple correlation has been reported. QAC surfactants are thought to interact with cell membranes through association of the positively charged quaternary nitrogen with the polar headgroups of some phospholipids. The hydrophobic tails of the surfactants subsequently interact with the hydrophobic region of the lipid bilayer. Insertion into the membrane can affect the structure and physical properties of the membrane, such as curvature, surface charge and lateral pressure, undermining the functioning of membrane proteins. The aim of this work is to determine how membrane structure changes with QAC biocide binding.