Fabrication of anisotropic magnetic helical microswimmers utilizing Spirulina platensis templates and their integration with Janus PCL/Chitosan nanoparticles.

Magnetically-actuated microswimmers are promising candidates for controlled cargo transport and microscale manipulation; however, achieving efficient, fuel-free propulsion with precisely defined anisotropic structures remains a significant fabrication challenge. We present a novel bio-hybrid helical microswimmer architecture that utilizes the bio-template of Spirulina platensis. This design incorporates anisotropic magnetite Janus nanoparticle (MJNP) heads made from hydrophilic chitosan and hydrophobic polycaprolactone (PCL). This architecture is created through a two-step dip-coating and anisotropic linking process, which ensures stability, magnetic responsiveness, and a defined structural asymmetry. To assess therapeutic potential, Doxorubicin (DOX) was loaded onto the MJNPs, and the biocompatibility of the microswimmers was confirmed in vitro. The microswimmers exhibited efficient corkscrew-like propulsion when exposed to rotating magnetic fields. By systematically tracking their trajectories in biofluids, we observed that increasing the number of helical turns significantly enhances both their forward velocity and translational diffusion. This directly correlates the length of the helices with the optimized conversion of rotational torque into translational motion. This study establishes a robust, bio-templated platform that provides valuable design insights for enhancing the functional versatility of helical microswimmers in advanced biomedical applications.