Artificial bacterial flagella functionalized with temperature-sensitive liposomes for controlled release

• Arrays of artificial bacterial flagella (ABFs) 16 μm in length were fabricated.
• A functionalization process to generate functionalized ABFs (f-ABFs) was developed.
• Hydrophobic and hydrophilic drug models carried by the f-ABFs were demonstrated.
• Temperature-triggered release of calcein (a drug model) from f-ABFs was studied.
• The f-ABFs may be used for targeted, triggered drug delivery in vitro and in vivo.

Inspired by flagellar propulsion of bacteria such as E. coli, artificial bacterial flagella (ABFs) are magnetic swimming microrobots with helical shapes. ABFs are capable of performing precise three-dimensional (3D) navigation in fluids under low-strength rotating magnetic fields making them attractive tools for targeted drug delivery. Further biomedical functionalization of these swimming microrobots is essential to enhance their biological and medical performances. We report the successful functionalization of titanium-coated ABFs with temperature-sensitive dipalmitoylphosphatidylcholine (DPPC)-based liposomes, known as “smart” drug carriers. Liposome coating on the surface of ABFs was confirmed using quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescent probes. The functionalized ABFs (f-ABFs) showed the ability to incorporate both hydrophilic and hydrophobic drugs. Finally, thermally triggered release of calcein (a common drug analog) from f-ABFs was demonstrated. These f-ABFs have the potential to be used in targeted and triggered drug delivery, microfluidic devices and biosensing.