Bacterial adhesion and the subsequent formation of biofilm are major concern in biotechnology and medicine. The initial stage for the nonspecific adsorption of proteins and polysaccharides on a surface and for the nonspecific attachment of bacteria onto the surface is a key determinant in the subsequent formation of biofilm. However, the molecular basis of the initial stage of nonspecific bacterial adhesion to artificial surfaces is not yet understood. Due to the limited stability or effectiveness of existing materials, it is desirable to develop next-generation nonfouling materials beyond poly (ethylene glycol) (PEG) and dextran to highly resist protein and polysaccharide adsorption, and bacterial adhesion/biofilm formation. Biomimetic zwitterionic-based materials are very promising.

This work is to evaluate the potential for three classes of materials - (a) hydrophilic (e.g., PEG), (b) zwitterionic (e.g., phosphobetaine), and (c) carbohydrates (e.g., dextran) to inhibit random bacterial adhesion (4 hours) and the subsequent formation of biofilm (24 hours). Self assembled monolayers (SAM) of three materials were prepared in this study. Both gram-positive Staphylococcus epidermidis and gram-negative Pseudomonas aeruginosa were used to quantify the degree of bacterial adhesion using laminar flow cell chambers. Attachment of both species to PEG, dextran, and PC SAM was compared to the basic methyl-terminated SAM.

The objectives of this work are to study the interactions of bacteria with a three classes of surfaces in the initial step of bacterial adhesion and long term biofilm formation to understand new materials that not only effectively resist protein adsorption, but also inhibit bacterial adhesion/biofilm formation. For various applications in biotechnology and medicine, PEG and dextran have been widely used. Due to their limited stability or effectiveness, it is desirable to develop nonfouling materials beyond PEG and dextran. Zwitterionic-based materials e.g. phosphobetaine, are very promising.