Development of bacteria-based microrobot using biocompatible poly(ethylene glycol).

For the development of bacteria-based biomedical microrobot, we propose the fabrication method of biocompatible poly(ethylene glycol) (PEG) microbeads using a cross-junction microfluidic channel. PEG droplets were polymerized by ultraviolet (UV) irradiation to form PEG microbeads of 8.18 ± 3.4 μm diameter in a microfluidic channel. Generally, the bacteria did not attach to the surface of the PEG microbeads because of their hydrophilicity. We modified the selective surface of the PEG microbeads using poly-L-lysine (PLL), promoting attenuated Salmonella typhimurium adhesion using the submerging property of PEG microbeads on agarose gel: the bacteria could thus be attached to the PLL-coated surface region of the PEG microbeads. The selectively PLL-coated PEG microbeads group showed enhanced motility compared with the PLL-uncoated and completely PLL-coated PEG microbeads groups. The selectively PLL-coated PEG microbeads group showed 12.33 and 7.40 times higher average velocities than the PLL-uncoated and completely PLL-coated PEG microbeads groups, respectively. This study verified the successful fabrication of bacteria-based microrobots using PEG microbeads, and the enhanced motility of the microrobots by selective bacteria patterning using agarose gel and PLL.