NUS I-FIM researchers have amplified a bacteria’s capacity to harness electricity by introducing a novel helper molecule, COE-NDI, improving its ability to catalyse chemical transformations.
Researchers from the Institute for Functional Intelligent Materials (I-FIM) at the National University of Singapore (NUS) have given bacteria a synthetic boost, transforming them into more efficient factories for converting electricity into chemicals. The cornerstone of this study is a new molecule named COE-NDI, the first example of an n-type redox-active conjugated oligoelectrolyte.
“This molecule has the unique ability to spontaneously embed itself into bacterial cell membranes, supercharging the bacteria’s capability to accept electricity,” explains Professor Guillermo Bazan, a principal investigator at I-FIM. “When integrated into specific bacteria, it remarkably amplified the electron uptake of these microbes from an external electrode by four-fold.”
In the context of semiconductors and organic electronics, p-type materials are those that are electron-rich and can donate electrons, while n-type materials are those that are electron-deficient and can accept electrons. Typically, most of the organic conjugated materials are p-type; however, the development of stable n-type materials has been an ongoing research focus in the field of organic electronics due to their value in certain optoelectronic applications.
Hence, the implications of the discovery of COE-NDI are vast and transformative. Leveraging the bacteria’s enhanced metabolic pathways could reshape our approach to biofuel generation and sustainable energy avenues. From a practical perspective, the study’s findings provide a vision to significantly improve the efficiency of bio-electroreduction, a process used to produce chemicals and biofuels—pushing the boundaries of sustainable industrial practices.
Harnessing nature’s design through human ingenuity
Bio-electrochemical systems, which convert electrical energy to chemical forms and vice versa, tap into bacteria’s innate ability to shuttle electrons, making these processes possible. These systems play a vital role in myriad bio-industrial processes, from wastewater treatment to the generation of valuable chemicals like hydrogen and methane. Their potential influence on resource management and energy production is profound.
“However, the crux of the challenge lies in these systems’ sluggish electron transfer rates,” said Prof Bazan. “The natural architecture of bacterial cell membranes acts as more as an insulator than a conductor, limiting electron mobility and, as a result, the system’s overall efficiency.”
To address this challenge, the researchers incorporated the newly designed molecule COE-NDI into the bacteria. Picture this molecule as a bridge—it nestles within the bacterial cell membrane, facilitating the swift passage of electrons.
Previous attempts have dabbled in similar strategies, but this study distinguishes itself with its novel approach. “Rather than merely boosting the bacterial count or wiring up only the cell surface to the electrode, we chose a different path—harnessing the power of redox-active COEs,” shared Mr Glenn Quek, a final-year PhD student at I-FIM, who is also the lead author of the paper. “This fundamentally alters the mechanism by which electrons are injected into bacteria.”
To discern the effects of this integration, the researchers turned to cyclic voltammetry, a method that tracks electron movement. They observed that electrons were indeed surging into bacterial cells through the COE-NDI bridge. Remarkably, COE-NDI breathed life into a bacterial strain that had mutated to lose its natural ability to accept electricity, enabling it to surpass even its naturally efficient counterparts.
The study was published in the journal Angewandte Chemie International Edition, and was featured on the cover of Volume 62, Issue 33.
Encouraged by the results, the team is optimistic about the future of this synthetic modification. “Moving forward, we plan to refine the COE-NDI molecule further and investigate its potential across a wider range of microbes,” added Mr Quek.
By exploring the previously unchartered territory of n-type COEs, the researchers stand on the brink of advancing bio-electrosynthetic processes, laying the groundwork for a sustainable generation of energy and chemicals.