There are many technical challenges. All the synthetics parts that you want to equip your bacteria with should add an extra function to your swimmer. For instance, in our case, magnetic nanoparticles are added for swimming control using external magnetic fields, and nanoliposomes loaded with drugs are added for the demonstration of on-demand, localized drug release. One needs to carefully choose these synthetic components for the desired application, and design them accordingly. They need to be compatible, non-toxic, ideally smaller than your microorganism, and fully functional. Also, your microorganism should be able to accommodate the attachment of these synthetic cargoes. We use something called “biotin-avidin” interaction to equip bacteria with the components, and this had previously required the genetic modification of bacteria to express “biotin” on their cell surfaces, which is not a simple task either. Microorganisms also shouldn’t stop swimming after the addition of the synthetic components, because we want to harness their motility for active therapeutic applications.

Overall, designing a tiny robot out of a living, motile microorganism requires extensive planning and design on material development, genetic engineering, microscopic imaging, and viability checks after modifications and testing of their functions after the construction is complete.

Thanks for your question!
All the best,
/birgül