Removal of a Model Biofilm by Sophorolipid Solutions: A QCM-D Study

Biofilms are communities of microorganisms that have been widely studied because they can cause hospital-acquired infections and skin disorders. Polysaccharides secreted by microorganisms are constituents of biofilms, contributing to their adhesion and mechanical stability. Sophorolipids are biosurfactants with the ability to disrupt and remove biofilms. Biosurfactants have been targeted as potential substitutes for classical petrochemical-based surfactants in cosmetics. In this study, we fabricate a beta-glucan film as a model biofilm, and quartz crystal microbalance with dissipation monitoring (QCM-D) measurements are used to assess the biofilm removal. The viscoelasticity of the beta-glucan films is monitored while sophorolipid solutions are introduced into the system, and we found that the film removal performance increases with the sophorolipid concentration. In addition, Af (change in frequency)-AD (change in energy dissipation) plot analyses reveal that two processes are involved in the removal mechanism. The first process involves the adsorption of water (hydration) on the beta-glucan film. The second process involves the removal of the beta-glucan film from the sensor surface. Furthermore, it is suggested that sophorolipids interfere with the hydration of the beta-glucan film and suppress increases in its viscosity. This is expected to be an essential factor for the removal of the beta-glucan film. Sophorolipids, therefore, show potential for use in cosmetics as an eco-friendly agent for biofilm removal.

Automated summary

In this study, the removal performance of sophorolipids on a beta-glucan film, a model biofilm, was evaluated using QCM-D measurements. The results showed that the removal performance increased with the concentration of sophorolipids, and two processes were involved in the removal mechanism: water adsorption and film removal from the sensor surface. It was suggested that sophorolipids interfere with the hydration of the beta-glucan film and suppress increases in its viscosity, which is expected to be an essential factor for the removal of the beta-glucan film. Sophorolipids demonstrate potential as eco-friendly agents for biofilm removal in cosmetics.