Design and development of integrated ultralow fouling and antimicrobial zwitterionic materials

This dissertation details the design and development of novel materials to resist bacterial colonization based on ultralow fouling materials and their integration with cationic compounds and antimicrobial agents. Antimicrobial agents can be incorporated into nonfouling materials as counterions, hydrolysis leaving groups, or encapsulated molecules.;For the strategy with non-fouling materials alone, zwitterionic poly(sulfobetaine methacrylate) (pSBMA) and poly(carboxybetaine methacrylate) (pCBMA) surfaces were evaluated for their resistance to nonspecific protein adsorption, bacterial adhesion (3h) and biofilm formation (over 24h). pSBMA reduced the adhesion of Staphylococcus epidermidis and Pseudomonas aeruginosa relative to bare glass by 92% and 96%, respectively. It was shown that the pCBMA surface resisted nonspecific protein adsorption from 100% plasma, and reduced long-term biofilm formation of P. aeruginosa by 95% up to 240 hours at 25°C; and by 93% for 64 hours at 37°C, relative to bare glass. The advantage of this approach is to delay bacterial adhesion and biofilm formation without using antimicrobial agents.;For the strategy with integrated cationic and nonfouling materials, a self-sterilizing and non-fouling polymer surface was developed to kill bacteria and prevent the attachment and bacterial colonization of the surface. Results showed that an hydrolysable antimicrobial cationic derivative of pCBMA killed 99.9% of Escherichia coli K12 and then released 98% of the killed E. coli K12 attached. The advantage includes a switchable surface to release killed microbes and to keep a clean surface upon hydrolysis.;For the strategies with integrated antimicrobial and nonfouling materials, a hydrogel based on the hydrolysable derivative of pCBMA was synthesized. Salicylate was incorporated into the hydrogel as an anionic counterion. Results showed that this hydrogel inhibited the growth of both S. epidermidis and Escherichia coli K12 by 99.9% compared to the zwitterionic control surface. This new strategy provides a controlled release of salicylate and creates a nonfouling surface, resulting in not only reduced bacterial adhesion but also the inhibited growth of planktonic bacteria.;Other two strategies include (a) the encapsulation of antimicrobial agents in zwitterionic nanogels, which are being further developed, and (b) incorporation of antibiotics as hydrolysable leaving groups (future work).