Magnetic motors in inhomogeneous environments Miguel A Ramos Docampo and Brigitte Städler Aarhus University, Denmark
Nano- and micromotors are a concept of active matter that display self-mobility. Locomotion can be attained either by converting any kind of energy into kinetic energy by leveraging fuel from (bio)chemical reactions occurring in the motor’s microenvironment (e.g., enzyme catalysis, red-ox reactions) or applying external physical stimuli (i.e., magnetic fields, light or ultrasounds). 1 Magnetic fields may be a convenient choice since they can be easily tuned and result harmless for biological purposes. Different examples of motors propelled by magnetic fields in several media can be found in literature, but little effort has been put on understanding the possibilities of magnetic motors crossing biological membranes. Examples usually include theoretical models where the motors have a similar size to the membrane they are supposed to cross, or they navigate in homogeneous environments Nonetheless, neither of these cases happen in real situations. Here, we present a class of magnetic motor to interact with lipid membranes and assess its performance. First, motors of four different sizes have been used to evaluate the impact of particle size on the lipid membrane interaction. Second, lipid membranes were prepared in the shape of giant unilamellar vesicles (GUVs) to facilitate the visualization. The lipid composition was changed to modify the charge and rigidity of the membrane. Finally, the evaluation of the motor navigating together with the GUVs was assessed. Three possible scenarios were envisioned: A) the motor was able to cross the lipid membrane and de-accelerate due to the change in viscosity; B) the motor could not cross the lipid membrane; and C) upon penetration, the motor could leave the GUV or not. Taken together, this research can help to understand the minimum requirements for motors to cross biological barriers, with a focus on experimental setups similar to those in real applications. References 1. M. Fernández-Medina, M. A. Ramos-Docampo, O. Hovorka, V. Salgueiriño and B. Städler, Recent advances in nano- and micromotors , Advanced Functional Materials , 2020, 1908283.
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© The Author(s), 2021
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