Abstract
Externally controlled microswimmers offer prospects for transport in biological research and medical applications. This requires biocompatibility of the swimmers and the possibility to tailor their propulsion mechanisms to the respective low Reynolds number environment. Here, we incorporate low amounts of the biocompatible alloy of iron and platinum (FePt) in its hbox {L1}_{{0}} phase in microstructures by a versatile one-step physical vapor deposition process. We show that the hard magnetic properties of hbox {L1}_{{0}} FePt are beneficial for the propulsion of helical micropropellers with rotating magnetic fields. Finally, we find that the FePt coatings are catalytically active and also make for Janus microswimmers that can be light-actuated and magnetically guided.
Highlights
Biomedical applications of micro- and nanoparticulate carriers based on liposomes and viruses or virus-like particles mostly rely on passive diffusion to reach their target site [1,2]
The samples grown at 18◦ with a nominal FePt thickness of 50 nm still exhibit an almost twofold increase in magnetic remanence (19 μemu mm−2) compared with the helices that have previously been grown at 83◦
High coercivities in the range of ∼ 1.5 T make them hard to re-magnetize while their high magnetic remanence (333 emu cm3) allows for their actuation through biologically relevant fluids such as cell media via the application of relatively weak ∼1–4 mT magnetic fields
Summary
Biomedical applications of micro- and nanoparticulate carriers based on liposomes and viruses or virus-like particles mostly rely on passive diffusion to reach their target site [1,2]. Such systemic applications require larger doses and are generally wasteful as most carriers do not reach their intended target [2]. We show that the FePt coating is catalytically active This opens the possibility to realize light-actuated iron–platinum microswimmers that are propelled by self-phoresis (see Fig. 1b) [15]
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