Recent work has shown that microrobots are capable of transporting cargo, such as cells, in a targeted manner. This functionality presents an opportunity to enhance the efficacy of cell-based therapies, for example, by enabling for the localized delivery of immune cells and immunotherapeutic drugs.

In this work, we use magnetically responsive microrobots attached to macrophages to address three gaps that limit the translatability of cell/microrobot complexes. First, we explore how macrophages interact with helical microrobots. Second, we characterize how the location of cell attachment produces alterations to the motion of cell/microrobot complexes in a rotating magnetic field. Lastly, we explore the efficacy of microrobots to enhance the transport of living cells and drugs through viscous fluid barriers such as mucus.

Helical microrobots, 50 microns in size, were fabricated with two-photon lithography and coated with chromium, nickel, and titanium to endow magnetic responsiveness in a biocompatible shell. Macrophages were added to the helices and the spatial distribution of cell attachment was characterized using confocal microscopy. After, we studied the locomotion of the cell/microrobot complexes in a rotating magnetic field. We found that the attachment location and number of cells attached had a deterministic effect on locomotion.

We conclude by demonstrating proof-of-concept therapeutic applicability. We loaded a small molecule drug into the polymeric bodies of the helical microrobots, characterized drug release, and showed that macrophage polarization can be guided in response to the released drug. Lastly, we explore locomotion in physiological representative healthy and diseased artificial mucus. Our work illustrates that magnetic helical microrobots can enhance the transport of living cells (e.g., immune cells, gene-altered cells) as therapies through viscous fluids for potential clinical use.

Nichole Loomis

Appearances