Navigating microalgal biohybrids through confinements with magnetic guidance

In the natural world, microorganisms constantly navigate through confined spaces—such as those found in tissues, biological gels, and soil—yet their behavior in such environments remains poorly understood. Here, we explore this phenomenon by examining the navigation of magnetic microalgal biohybrids in constrained microenvironments. By leveraging the inherent propulsion of green microalgae and external steering capabilities acquired through the magnetization of microalgal cells, our biohybrids exhibit efficient navigation in viscous and confined microenvironments. Through high-yield fabrication and magnetic manipulation, we show precise control over their movement. Our findings reveal distinct navigation patterns influenced by magnetic guidance, namely backtracking and crossing, shedding light on the unexplored dynamics of confined locomotion assisted by magnetism. Our work highlights the significance of understanding microalgal biohybrid swimming behavior, offering crucial insights for future biotechnological and biomedical applications requiring precise navigation in confined environments. • High-yield design for microalgal biohybrids enabling external magnetic steering • Biohybrids show effective navigation through 2D and 3D confined environments • Unique swimming patterns in confinements under magnetic guidance Understanding the navigation of microorganism-based biohybrid swimmers in confined environments holds critical implications for various applications spanning medicine, environment, and biotechnology. Our work introduces a high-yield design strategy for microalgal biohybrids, which can be externally steered by magnetic fields while preserving microalgal motility. Precise magnetic alignment of biohybrids provides effective transition through two-dimensional and three-dimensional confinements, surpassing the propulsion capabilities of free swimmers. Furthermore, by controlling their propulsion using magnetic guidance, we uncover navigation behaviors, such as backtracking and crossing, highlighting various dynamics in confined locomotion guided by magnetism. This insight not only advances our comprehension of microalgal biohybrid behavior but also holds promise for diverse biotechnological scenarios, where magnetic steering outperforms the motility of free-swimming organisms through their natural taxis. Our study offers significant insights into the behavior of engineered microorganisms—microalgal biohybrids, which can be externally steered using magnetic fields. By studying these biohybrids in narrow microenvironments that mimic conditions found in the human body and using magnetic guidance, our research reveals unique navigation strategies and dynamics. Our discoveries pave the way for revolutionary biomedical applications, where precise navigation in restricted spaces is critical.