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

Carsten-Rene Arlt,Dominik Brekel,Stefan Neumann,David Rafaja,Matthias Franzreb

doi:10.1007/s11705-021-2040-3

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.

Highlights

Magnetic nanoparticles (MNPs) are becoming increasinglyReceived November 24, 2020; accepted January 14, 2021Carsten-Rene Arlt et al Continuous size fractionation of magnetic nanoparticles for MNPs is the use of so-called high gradient magnetic separators [31,32]
The fractionation effect could be explained by the fact that MNPs, due to their size, only consist of single-domain magnetic systems, which show a spontaneous magnetization [41]
These advantages were enhanced in this study by converting the system from a batch mode to a continuous process by applying the principle of simulating moving bed chromatography (SMB)

Summary

Introduction

Magnetic nanoparticles (MNPs) are becoming increasinglyReceived November 24, 2020; accepted January 14, 2021Carsten-Rene Arlt et al Continuous size fractionation of magnetic nanoparticles for MNPs is the use of so-called high gradient magnetic separators [31,32]. In a previous work we already observed size fractionation effects for MNPs in a magnetically responsive matrix without the use of an external magnetic field [40] For this purpose, a chromatography column was filled with a steel matrix, which showed good suitability due to its high saturation magnetization and low remanence. A further advantage is the increased durability of the fractionation matrix materials, since the variation in the magnetic field could lead to a remanence of the same and to a loss of MNP and a reduction in fractionation performance These advantages were enhanced in this study by converting the system from a batch mode to a continuous process by applying the principle of simulating moving bed chromatography (SMB). To the best of our knowledge, we are the first to show a continuous size fractionation process based on a SMB combined with magnetic chromatography, which features good scalability

Methods

Results

Conclusion