Modeling Bacterial Attachment Mechanisms on Superhydrophobic and Superhydrophilic Substrates

• Main Authors: T. Brian Cavitt (Author), Niyati Pathak (Author)
• Format: Book
• Published: MDPI AG, 2021-09-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

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 (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>A</mi><mi>B</mi></mrow></msup></mrow></semantics></math></inline-formula>) are often more significant than nonpolar (Lifshitz-van der Waals) interactions (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>L</mi><mi>W</mi></mrow></msup></mrow></semantics></math></inline-formula>). Classical DLVO theory alone also fails to address all colloidal interactions present in bacterial dispersions such as <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>A</mi><mi>B</mi></mrow></msup></mrow></semantics></math></inline-formula> and Born repulsion (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>B</mi><mi>o</mi><mi>r</mi><mi>n</mi></mrow></msup></mrow></semantics></math></inline-formula>) yet accounts for the significant electrostatic double layer repulsion (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>E</mi><mi>L</mi></mrow></msup></mrow></semantics></math></inline-formula>). We purpose to model both motile (e.g., <i>P. aeruginosa</i> and <i>E. coli</i>) and nonmotile (e.g., <i>S. aureus</i> and <i>S. epidermidis</i>) 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: <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>L</mi><mi>W</mi></mrow></msup></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>A</mi><mi>B</mi></mrow></msup></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>E</mi><mi>L</mi></mrow></msup></mrow></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>B</mi><mi>o</mi><mi>r</mi><mi>n</mi></mrow></msup></mrow></semantics></math></inline-formula>. The combination of the aforementioned interactions yields the total Gibbs interaction energy (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msup><mi>G</mi><mrow><mi>t</mi><mi>o</mi><mi>t</mi></mrow></msup></mrow></semantics></math></inline-formula>) of each bacterium with each substrate. Analysis of the interaction energies with respect to the distance of approach yielded an equilibrium distance (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>d</mi><mrow><mi>e</mi><mi>q</mi></mrow></msub></mrow></semantics></math></inline-formula>) that seems to be independent of both bacterial species and substrate. Utilizing both <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>d</mi><mrow><mi>e</mi><mi>q</mi></mrow></msub></mrow></semantics></math></inline-formula> and Gibbs interaction energies, substrates could be designed to inhibit bacterial attachment.

Item Description

10.3390/ph14100977
1424-8247