Responsive surfaces are able to switch their properties in response to a stimulus or change in the environment. Switchable surfaces composed of grafted polymers are capable of dynamic switching and may, therefore, be favorable for applications in self-cleaning surfaces, life sciences, and cosmetics. The switching mechanism in such responsive systems is realized via molecular reconstruction of polymer chains governed by the thermodynamic principle of surface energy conservation.We synthesized hybrid molecular brushes (HMB) by grafting hydrophilic polyacrylamide and hydrophobic polystyrene side chains onto a backbone of chitosan. Chitosan is an abundant biopolymer inexpensively derived from natural sources. Chitosan possesses unique properties that allow for convenient grafting by radical polymerization. Also, it is rich in other functionalities that allow for simple immobilization on different surfaces.We show that chitosan HMB can be immobilized on the substrate surface using multi-site polymer monolayer attachment or through quasi-irreversible adsorption of the backbone. Immobilized HMB demonstrate outstanding response to the changes in the environment as demonstrated by micro-adhesion and contact angle measurements.We used several prokaryotic cell lines (Escherichia coli DH5a and Salmonella typhimirium LT2) as a model to study the mechanism of bio-adhesion to such responsive surfaces. The cells are transformed with a plasmid containing a lux operon that is modified to create its own substrate for bioluminescence of the luciferase gene. Our results show that the cell adhesion can be efficiently controlled by external stimuli such as pH or Red-Ox potential. Further analysis of the cellular fimbria which attach to the surface will allow a better understanding of the mechanism of cell adhesion.

Responsive polymer surfaces for controlled cell adhesion

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.