AlgaeSperm: Microalgae‐Based Soft Magnetic Microrobots for Targeted Tumor Treatment

Abstract Magnetic microrobots are significant platforms for targeted drug delivery, among which sperm‐inspired types have attracted much attention due to their flexible undulation. However, mass production of sperm‐like soft magnetic microrobots with high‐speed propulsion is still challenging due to the need of more reasonable structure design and facile fabrication. Herein, a novel strategy is proposed for large‐scale preparation of microalgae‐based soft microrobots with a fully magnetic head‐to‐tail structure, called AlgaeSperm with robust propulsion and chemo‐photothermal performance. This approach deposited Pd@Au nanoparticles (NPs) inside chlorella cells, which are further coated with Fe 3 O 4 NPs and polydopamine layers to form the magnetic heads. Then, flexible flagella are grafted via magnetic assembly of Fe 3 O 4 @PVP NPs to construct the final AlgaeSperm. Under precessing magnetic fields, the AlgaeSperms can achieve a forward velocity up to 2.3 body length/s, the highest among sperm‐like magnetic microrobots to the best of the knowledge. Besides, their flexible maneuverability in a swarm is also verified. In vitro anti‐cancer experiments are conducted after loading doxorubicin (DOX) to confirm their excellent targeted chemo‐photothermal performance. This work offers a significant paradigm for constructing sperm‐like soft magnetic microrobots with great potential for targeted tumor treatment.