A Macrophage-Magnesium Hybrid Biomotor: Fabrication and Characterization.

Magnesium (Mg)-based micromotors are combined with live macrophage (MΦ) cells to create a unique MΦ-Mg biohybrid motor system. The resulting biomotors possess rapid propulsion ability stemming from the Mg micromotors and the biological functions provided by the live MΦ cell. To prepare the biohybrid motors, Mg microparticles coated with titanium dioxide and poly(l-lysine) (PLL) layers are incubated with live MΦs at low temperature. The formation of such biohybrid motors depends on the relative size of the MΦs and Mg particles, with the MΦ swallowing up Mg particles smaller than 5 µm. The experimental results and numerical simulations demonstrate that the motion of MΦ-Mg motors is determined by the size of the Mg micromotor core and the position of the MΦ during the attachment process. The MΦ-Mg motors also perform biological functions related to free MΦs such as endotoxin neutralization. Cell membrane staining and toxin neutralization studies confirm that the MΦs maintain their viability and functionality (e.g., endotoxin neutralization) after binding to the Mg micromotors. This new MΦ-Mg motor design can be expanded to different types of living cells to fulfill diverse biological tasks.