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.