Magnetic oriented microparticles preparation

Abstract

Generally speaking, reaction platforms involving ferromagnetic surfaces, with a specific magnetic direction, are limited to the two dimensional regime, due to the nature of the magnetic phenomena. Here we show a method for preparing partially coated ferromagnetic microparticles with a distinct magnetic pole. This simple preparation method was presented previously ^{[ 1 ]} to demonstrate an application for enantiomeric separation. In this method article we show;•A simple method to a-symmetrically manipulate particle surfaces.•A generic way to synchronize a bare pole of ferromagnetic microparticles.•A simple and generic enantiomer purification technique.

Keywords: CISS effect; Janus particles; Magnetic particles; Spin controlled enantiomer separation.

Graphical abstract

Fig. 1

Scheme of the entire process; A-B. deposition and drying of the microparticles on a glass substrate, C. 10 min treatment inside the plasma asher device, D. Magnetization under 2500 Oersted magnetic field (electromagnet), E. Washing and collecting of the microparticles into a filter paper.

Fig. 2

Scheme of the final particle after applying a magnetic field. The chart is not to scale; the ligands are represented in the purple layer. The spin direction is defined by the external induction of the electromagnetic field after the plasma operation.

Fig. 3

MagellanTM 400 L SEM images of the Chromium oxide rods, which comprise the shell of the microparticle, covering its polystyrene core, before A) and after B) the plasma asher process. C) A wide-angle perspective of whole microparticles. D) Magnetic hysteresis loop of the particles measured using a superconducting quantum interference device (SQUID), before and after the plasma asher process. In this measurement the sample was kept at room temperature.

Fig. 4

Anomalous Hall effect of the particles before (step 2) and after (step 3) palsma, at RT (blue) and at liquid N₂ temperature (green). Measurements of the Hall effect under 0.5 T give similar results.

Fig. 5

(A) A typical drop at the edge region of the microparticle film after the plasma treatment. (B) - A typical drop at the center region of the microparticle film before the plasma asher treatment. (C) - A typical drop at the edge region of the microparticle film before the plasma asher treatment. (D) - A typical drop at the center region of the microparticle film, following the plasma treatment and the mixing and redepositing of the particles. (E) - A typical drop at the edge region of the film, following the plasma treatment and the mixing and redepositing of the particles.