High‐Performance Magnetic FePt (L1₀) Surface Microrollers Towards Medical Imaging‐Guided Endovascular Delivery Applications (Adv. Funct. Mater. 8/2022)

Remotely Guided Immunobots Engaged in Anti‐Tumorigenic Phenotypes for Targeted Cancer Immunotherapy

“…We used the FePt film for its convenient properties, including high coercivity, chemical stability, and biocompatibility. [ 15 ] We performed the thin FePt coating (60 nm thickness) using a molecular epitaxy system described previously. [ 15a ] Since the particle size was slightly different compared to the previous design, we confirmed the uniform coating of the FePt layer (60 nm thickness) around half of the silica particles with images acquired by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) (Figure S1, Supporting Information).…”

“…[ 15 ] We performed the thin FePt coating (60 nm thickness) using a molecular epitaxy system described previously. [ 15a ] Since the particle size was slightly different compared to the previous design, we confirmed the uniform coating of the FePt layer (60 nm thickness) around half of the silica particles with images acquired by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) (Figure S1, Supporting Information). The half coating with FePt was required to provide shape anisotropy, allowing efficient and robust control of microparticles’ orientation and velocity.…”

“…Once this threshold is reached, the rotation speed is no longer linearly proportional to the rotation frequency, and the immunobots could no longer overcome the resistive torque exerted by the fluid, resulting in a rapid velocity decrease. [ 15b,19 ] Here, we also measured the step‐out frequency and corresponding maximum mean velocities of immunobots by gradually increasing the rotational frequency of the magnetic field. The step‐out frequency under 10 mT field strength was measured at 30 Hz with a maximum mean velocity of 82.2 µm s −1 ( Figure A).…”

“…The thin coating of silica particles with FePt alloy (L1 0 phase, 60‐nm thickness) was performed in a molecular beam epitaxy chamber under ultrahigh vacuum conditions (≈2–5 × 10 −9 mbar) as described and characterized previously. [ 15a ] The deposition of FePt is followed by an annealing step at 680 °C for 1 h. After deposition, the FePt‐coated silica particles were collected in ethanol by sonication for further experiments.…”

Ultrasound‐Controlled Swarmbots Under Physiological Flow Conditions

“…demonstrated upstream navigation of magnetic micro rollers on various 3D surface micro topographies. [ 34,35 ] Finally, Wang et al. used magnetic swarms that could assemble in stagnant conditions and subsequently be manipulated upstream.…”