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

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. (C) 2014 Elsevier B.V. All rights reserved.