PT - JOURNAL ARTICLE AU - Magdanz, Veronika AU - Khalil, Islam S. M. AU - Simmchen, Juliane AU - Furtado, Guilherme P. AU - Mohanty, Sumit AU - Gebauer, Johannes AU - Xu, Haifeng AU - Klingner, Anke AU - Aziz, Azaam AU - Medina-Sánchez, Mariana AU - Schmidt, Oliver G. AU - Misra, Sarthak TI - IRONSperm: Sperm-templated soft magnetic microrobots AID - 10.1126/sciadv.aba5855 DP - 2020 Jul 01 TA - Science Advances PG - eaba5855 VI - 6 IP - 28 4099 - http://advances.sciencemag.org/content/6/28/eaba5855.short 4100 - http://advances.sciencemag.org/content/6/28/eaba5855.full SO - Sci Adv2020 Jul 01; 6 AB - We develop biohybrid magnetic microrobots by electrostatic self-assembly of nonmotile sperm cells and magnetic nanoparticles. Incorporating a biological entity into microrobots entails many functional advantages beyond shape templating, such as the facile uptake of chemotherapeutic agents to achieve targeted drug delivery. We present a single-step electrostatic self-assembly technique to fabricate IRONSperms, soft magnetic microswimmers that emulate the motion of motile sperm cells. Our experiments and theoretical predictions show that the swimming speed of IRONSperms exceeds 0.2 body length/s (6.8 ± 4.1 µm/s) at an actuation frequency of 8 Hz and precision angle of 45°. We demonstrate that the nanoparticle coating increases the acoustic impedance of the sperm cells and enables localization of clusters of IRONSperm using ultrasound feedback. We also confirm the biocompatibility and drug loading ability of these microrobots, and their promise as biocompatible, controllable, and detectable biohybrid tools for in vivo targeted therapy.