We evaluated self-assembled monolayers (SAMs) as potential coatings to prevent bacterial adhesion to biomaterials.Bacterial retention experiments were conducted on SAMs, some of which were coated with the model proteins fetalbovine serum (FBS) and fibronectin (FN). A thermodynamic approach was applied to calculate the Gibbs free energychanges of adhesion (
Gadh) of
Staphylococcus epidermidis interacting with the substrates. When only nonspecificinteractions controlled bacterial attachment, such as for the non-protein-coated substrates or the FBS substrates, thecorrelation between the thermodynamic predictions and measured values of bacterial retention was strong. However,when FN was adsorbed to the surfaces, the thermodynamic modeling underestimated bacterial adhesion, presumablysince specific interactions between proteins of
S. epidermidis and FN led to stronger attachment. Bacterial viabilityon the substrates was correlated with thermodynamic properties. For example, although bacteria attached more tosurfaces having negative
Gadh values, these cells experienced the greatest loss of viability, presumably since stronglyattached bacteria were unable to divide and grow. When the
Gadh values were decoupled into their components, wesaw that acid-base interactions due to hydrogen bonding dominated the interactions of bacteria and proteins witheach other and with the substrates in aqueous media. Finally, we discuss concerns regarding the use of the thermodynamicmodel to predict bacterial adhesion behavior in biomaterials systems.