Modeling Bacterial Attachment Mechanisms on Superhydrophobic and Superhydrophilic Substrates

Superhydrophilic and superhydrophobic substrates are widely known to inhibit the attachment of a variety of motile and/or nonmotile bacteria. However, the thermodynamics of attachment are complex. Surface energy measurements alone do not address the complexities of colloidal (i.e., bacterial) dispersions but do affirm that polar (acid-base) interactions ([Formula: see text]) are often more significant than nonpolar (Lifshitz-van der Waals) interactions ([Formula: see text]). Classical DLVO theory alone also fails to address all colloidal interactions present in bacterial dispersions such as [Formula: see text] and Born repulsion ([Formula: see text]) yet accounts for the significant electrostatic double layer repulsion ([Formula: see text]). We purpose to model both motile (e.g., P. aeruginosa and E. coli) and nonmotile (e.g., S. aureus and S. epidermidis) bacterial attachment to both superhydrophilic and superhydrophobic substrates via surface energies and extended DLVO theory corrected for bacterial geometries. We used extended DLVO theory and surface energy analyses to characterize the following Gibbs interaction energies for the bacteria with superhydrophobic and superhydrophilic substrates: [Formula: see text] , [Formula: see text] , [Formula: see text] , and [Formula: see text]. The combination of the aforementioned interactions yields the total Gibbs interaction energy ([Formula: see text]) of each bacterium with each substrate. Analysis of the interaction energies with respect to the distance of approach yielded an equilibrium distance ([Formula: see text]) that seems to be independent of both bacterial species and substrate. Utilizing both [Formula: see text] and Gibbs interaction energies, substrates could be designed to inhibit bacterial attachment.