Image: SEM images of E. coli attached to Janus particles
Bacteria such as E. coli – which is better known to the general public as the bacterium that causes food poisoning, although a non-pathogenic type occurs naturally in the gut, as do countless other types of bacteria that carry out good work in the body – can be harnessed to power such micromotors within a living organism by converting the surrounding chemical energy into mechanical work. They therefore count as bio-friendly fuels, whereas up until now micromotors have relied on toxic fuel sources and materials in their design, making them irrelevant for biomedical applications.
To achieve the bacteria-powered micromotors, the researchers integrated E. coli onto metal-capped, polystyrene Janus particles – special types of particles whose surfaces have two or more distinct physical properties. The E. coli preferred platinum of all the four types of metals tested, and adhered only to the metal side, allowing the particle’s polystyrene surface to be used to attach the drug. “Our bio-hybrid was capable of carrying a load of up to 2 µm in diameter, and demonstrated the ability to transport DOX, an anti-cancer drug,” says Samuel.
The bio-hybrid has dual capability – guided cell adhesion and localized drug attachment – as well as being capable of swimming in confined micro-environments that are otherwise inaccessible. Future challenges of bacteria-powered swimmers will be to operate in in vivo systems with a more complex 3D swimming environment, but a better understanding of the bacteria-surface interface will be essential for their success.
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Article: Morgan M. Stanton, Juliane Simmchen, Xing Ma, Albert Miguel-López, Samuel Sánchez* (2015). Bio-hybrid Janus Motors Driven by Escherichia coli. Adv Mat Interfaces, 3, 2
