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Reduced biofilm formation is highly desirable in
applications ranging from transportation to separations and
healthcare. Biofilms often form at the three-phase interface
where air, liquid, and solid coexist due to the close proximity to
nutrients and oxygen. Reducing biofilm formation at the triple
interface presents challenges because of the conflicting requirements
for hydrophobicity at the air−solid interface (for selfcleaning
properties) and for hydrophilicity at the liquid−solid
interface (for reduced foulant adhesion). Meeting those needs
simultaneously likely entails a dynamic surface, capable of shifting
the surface energy landscape in response to wetting conditions and
thus enabling hydrophobicity in air and hydrophilicity in water.
Here, we designed a facile approach to render existing surfaces
resistant to biofilm formation at the triple interface. By adding trace amounts (∼0.1 mM) of surfactants, biofilm formation of
Pseudomonas aeruginosa (known to form biofilm at the triple interface) was reduced on all surfaces tested, ranging from hydrophilic
to hydrophobic, polar to nonpolar. That reduced fouling was not a result of the known antimicrobial effects. Instead, it was attributed
to the surface-adsorbed surfactants that dynamically control surface energy at the triple interface. To further understand the effect of
surfactant−surface interactions on biofilm reduction, we systematically varied the surfactant charge type and surface properties
(surface energy and charge). Electrostatic interactions between surfactants and surfaces were identified as an influential factor when
predicting the relative fouling reduction upon introduction of surfactants. Nevertheless, biofilm formation was reduced even on the
charge-neutral, fluorinated surface made of poly(1H, 1H, 2H, 2H-perfluorodecyl acrylate) by more than 2-fold simply via adding 0.2
mM dodecyl trimethylammonium chloride or 0.3 mM sodium dodecyl sulfate. Given its robustness, this strategy is broadly
applicable for reducing fouling on existing surfaces, which in turn improves the cost-effectiveness of membrane separations and
mitigates contaminations and nosocomial infections in healthcare.
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