Continuous size fractionation of magnetic nanoparticles by using simulated moving bed chromatography

Abstract

The size fractionation of magnetic nanoparticles is a technical problem, which until today can only be solved with great effort. Nevertheless, there is an important demand for nanoparticles with sharp size distributions, for example for medical technology or sensor technology. Using magnetic chromatography, we show a promising method for fractionation of magnetic nanoparticles with respect to their size and/or magnetic properties. This was achieved by passing magnetic nanoparticles through a packed bed of fine steel spheres with which they interact magnetically because single domain ferro-/ferrimagnetic nanoparticles show a spontaneous magnetization. Since the strength of this interaction is related to particle size, the principle is suitable for size fractionation. This concept was transferred into a continuous process in this work using a so-called simulated moving bed chromatography. Applying a suspension of magnetic nanoparticles within a size range from 20 to 120 nm, the process showed a separation sharpness of up to 0.52 with recovery rates of 100%. The continuous feed stream of magnetic nanoparticles could be fractionated with a space-time-yield of up to 5 mg/(L·min). Due to the easy scalability of continuous chromatography, the process is a promising approach for the efficient fractionation of industrially relevant amounts of magnetic nanoparticles.

Magnetic/flow controlled continuous size fractionation of magnetic nanoparticles using simulated moving bed chromatography

“…Jungbauer et al were successful in using classical size exclusion SMB for the separation of protein loaded silica nanoparticles with a size of about 70 nm from unbound protein [41] In another approach, a SMB method for nanoparticle separation could be demonstrated in one of our works by separating two nanoparticle types with different susceptibilities from each other [42]. In a recent work, we were able to use such a SMB process for size fractionation of MNPs for the first time [43]. Fractionation was obtained based on the spontaneous magnetization of single domain MNPs without the application of external magnetic fields.…”

“…Therefore, in contrast to the work reported in Ref. [43], here an external magnetic field is applied in order to enhance and align the magnetization of the MNPs. In this case, the magnetic force acting onto the MNPs is a volume force, increasing with the cubic of the MNP diameter assuming an ideal spherical shape:…”

Isolation and Purification of Single Gold Nanoclusters by Alternate Pumping Chromatography

“…Several process concepts exist that provide enhanced performance in preparative applications; for overviews, see [21][22][23]. These include gradients, multi-column schemes, such as the simulated moving bed concept [24,25], as well as recycling processes. The latter are particularly interesting for the problem at hand.…”

Aufreinigung von Nano‐ und Submikronpartikeln durch präparative Gelelektrophorese

“…Die kleineren Partikel diffundieren dabei sta ¨rker in die Porenstrukturen hinein, was zu einer verla ¨ngerten Retentionszeit und somit zu einer gro ¨ßenabha ¨ngigen Trennung fu ¨hrt. Magnetische NP ko ¨nnen durch eine magnetische Chromatographiesa ¨ule geleitet werden, wo sie aufgrund ihrer unterschiedlichen Partikelgro ¨ßen unterschiedlich starke magnetische Anziehungskra ¨fte zu dem stationa ¨ren Sa ¨ulenmaterial erfahren und sich somit u ¨ber ungleiche Verweilzeiten in der Trennsa ¨ule auftrennen [8]. Des Weiteren ko ¨nnen Nano-und Submikronpartikel durch mikrofluidische Kana ¨le geleitet werden, wobei die Trennung in Kana ¨len mit definierten Stro ¨mungen (Asymmetrische Fluss-Feldflussfraktionierung, AFFFF) oder besonderen Formen (multi-orifice flow fractionation, MOFF oder Serpentinenkanal), durch Hindernisse im Kanal (deterministic lateral displacement, DLD), durch akustische Wellen oder durch Anlegen eines inhomogenen elektrischen Feldes (Dielektrophorese) herbeigefu ¨hrt wird [9][10][11].…”