Living polymerization has emerged as a robust tool to synthesize polymers with defined structures for nanocomposites and biomaterials. Numerous efforts were devoted in the past decade to expanding this controlled radical polymerization method. However, due to restriction of special design, susceptible to oxygen and less control in aqueous buffers, challenges still remain. To address these difficulties, we'll discuss how extracellular electron transfer (EET) can be leveraged to enhance the radical polymerization by coupling metabolism to an extracellular catalytic cycle. Specifically, we used the electrochemically-active bacterium Shewanella oneidensis to control a living radical polymerization via electron transfer to a transition metal catalyst. Precise control over the molecular weight and polydispersity of synthetic polymer could be achieved by mixing the S. oneidensis suspension into the reaction medium while non-electroactive organisms, such as Escherichia coli, showed no significant activity. We also found that polymerization performance was closely related to the bacterial metabolism, specific electron transport proteins and catalyst structure, offering potential targets for future applications. Excitingly, we found that S. oneidensis can control metal-catalyzed living radical polymerizations under aerobic conditions by first consuming dissolved oxygen via aerobic respiration, then directing extracellular electron flux to the polymerization catalysts. In both open and closed containers, S. oneidensis enabled living radical polymerizations without requiring the pre-removal of oxygen. Polymerization activity was effective for wide ranges of monomers using low concentrations of biocompatible, non-noble metal catalysts including cobalt and iron. Furthermore, polymerization activity could be resumed using lyophilized or spent (recycled) cells. Overall, our results suggest that manipulating EET pathways of microbes may be a general strategy for revolutionizing the conventional living radical polymerization.

Whole-cell controlled living polymerization by electrochemically-active bacteria

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ACS Fall 2022

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