Reusable nanoengineered surfaces for bacterial recruitment and decontamination

Biofouling, or accumulation of unwanted biofilms, on surfaces is a major concern for public health and human industry. Materials either avoiding contamination (fouling resistant) and/or directly killing attached microbes (biocidal) have thus far failed to achieve the goal of eliminating biofouling; fouling resistant surfaces eventually foul and biocidal surfaces accumulate debris that eventually decrease their efficacy. Combined biocidal and fouling release materials offer the potential for both killing and removing debris and are promising candidates for reducing biofouling on manufactured materials. Interference lithography was used to create nanopatterns of initiators, which were then used to initiate atom transfer radical polymerization of the temperature-responsive polymer, poly(N-isopropylacrylamide) (PNIPAAm) as a fouling release component. Biocidal activity was conferred by subsequent layer-by-layer deposition of cationic and anionic poly(phenylene ethynylenes) into the valleys between the PNIPAAm. For both Gram positive and Gram negative model bacteria, dark-regime biocidal activity was observed that did not increase upon exposure to light, suggesting that the mode of antimicrobial activity is due to ionic disruption of the cell wall. Subsequent to killing, bacteria and cellular debris were removed upon a temperature-induced phase transition of the PNIPAAm. These materials exhibited capture, killing, and release activity over multiple cycles of use.