An approach for batch preparation of liposome-functionalized microdevices is demonstrated for remotely controlled single-cell drug delivery. The liposome functionalized artificial bacterial flagella exhibit corkscrew swimming in 3D with micrometer positioning precision by applying an external rotating magnetic field. The devices are also capable of delivering water-soluble drugs to single cells in vitro.

Inspired by flagellar propulsion of bacterial such as E. coli, artificial bacterial flagella (ABFs) are magnetic swimming microrobots with helical shapes. ABFs can perform precise three-dimensional (3D) navigation in liquids under low-strength rotating magnetic fields making them attractive tools for drug delivery applications. Further functionalization of these swimming microrobots is necessary to optimize their performance of biomedical tasks. We report here for the first time the successful functionalization of titanium-coated ABFs with temperature-sensitive dipalmitoylphosphatidylcholine (DPPC) liposomes. Adsorption of intact liposomes on titanium was assessed using quartz crystal microbalance with dissipation monitoring (QCM-D). The adsorption of fluorescently labeled liposomes on the surface of ABFs was confirmed with confocal laser scanning microscopy (CLSM) images. Functionalized ABFs (f-ABFs) can be loaded with both hydrophilic and hydrophobic drugs, and controlled drug release triggered by temperature. ABFs have a great potential to be used in targeted and controlled drug delivery and for in vivo sensing.