Sequential and simultaneous adsorption of mucin–4-[(dodecylimino)methyl]-N,N,N-trimethyl anilinium iodide mixed system using drop profile analysis tensiometry

The displacement of mucin from the droplet simultaneously and sequentially was studied using drop profile analysis tensiometry (PAT-1) instrument equipped with special designed instrument to allow the bulk exchange of the droplet. The dynamic and equilibrium surface tension profiles were used to discuss the stability of the formed mixed surfactant–protein layer at the interface. The viscoelastic data also were used to determine the extent of protein at the interface. The results showed that the simultaneously formed surfactant–protein layer at the complex is more surface active than that formed sequentially. The results were discussed according different mechanisms describing the interaction between the protein molecules and the cationic surfactant. The study explained the antimicrobial activity of the studied surfactant in the biological field.

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► Cationic surfactants can displace protein from the droplet surface either simultaneously or sequentially.
► The type of displacements in case of cationic surfactant has a great effect on the surface activity of the formed surfactant-complex.
► The interaction between surfactant and protein molecules is governed by the net charges on both molecules.
► Cationic surfactant–mucin complex formed simultaneously is more surface active than that formed sequentially.