Cargo size limits and forces of cell-driven microtransport

Abstract: The integration of motile cells into biohybrid microrobots offers unique properties such as sensitive responses to external stimuli, resilience, and intrinsic energy supply. Here we study biohybrid microtransporters that are driven by amoeboid Dictyostelium discoideum cells and explore how the speed of transport and the resulting viscous drag force scales with increasing radius of the spherical cargo particle. Using a simplified geometrical model of the cell-cargo interaction, we extrapolate our findings towards larger cargo sizes that are not accessible with our experimental setup and predict a maximal cargo size beyond which active cell-driven transport will stall. The active forces exerted by the cells to move a cargo show mechanoresponsive adaptation and increase dramatically when challenged by an external pulling force, a mechanism that may become relevant when navigating cargo through complex heterogeneous environments.