Engineering a Bacterial Flagella Forest for Sensing and Actuation – A Progress Report

Flagella can be used to make magnetically-controlled microfluidic and nanoscale devices for biomedical applications in both vitro and vivo environments. They are capable of operating with high precision on the cellular and subcellular level. So far, scientists and engineers have successfully used monolithic inorganic materials or photoactive polymers [1] to mimic the helical bacterial flagella whose rotary-propulsion mechanism effectively overcomes the dominant viscous forces that prevail in a low Reynolds-number environment. Here, we focus on bacterial flagella and their rotary motion. The bacterial flagellum is an ideal biomaterial for constructing self-propelling nanoswimmers because it can reversibly change its geometry in response to different environmental stimuli such as pH, the local concentration of certain organic solvents, and mechanical force on the flagella. The bacterial flagellum is very easy to manipulate because it is composed of flagellin which can be mechanically isolated through vortexing and centrifugation, which enables flagella to be used as nanoscale sensors and mechanical transducers. Our project focuses on fabricating a bacterial flagella forest which consists of an ordered array of flagella on a glass substrate. Flagella are attached to magnetic nanobeads via biotin-avidin bonding for actuation by oscillating magnetic field