Kinetic and Parametric Analysis of the Separation of Ultra-Small, Aqueous Superparamagnetic Iron Oxide Nanoparticle Suspensions under Quadrupole Magnetic Fields

Abstract

Superparamagnetic iron oxide nanoparticles (SPIONs) have gathered tremendous scientific interest, especially in the biomedical field, for multiple applications, including bioseparation, drug delivery, etc. Nevertheless, their manipulation and separation with magnetic fields are challenging due to their small size. We recently reported the coupling of cooperative magnetophoresis and sedimentation using quadrupole magnets as a promising strategy to successfully promote SPION recovery from media. However, previous studies involved SPIONs dispersed in organic solvents (non-biocompatible) at high concentrations, which is detrimental to the process economy. In this work, we investigate, for the first time, the magnetic separation of 20 nm and 30 nm SPIONs dispersed in an aqueous medium at relatively low concentrations (as low as 0.5 g·L−1) using our custom, permanent magnet-based quadrupole magnetic sorter (QMS). By monitoring the SPION concentrations along the vessel within the QMS, we estimated the influence of several variables in the separation and analyzed the kinetics of the process. The results obtained can be used to shed light on the dynamics and interplay of variables that govern the fast separation of SPIONs using inexpensive permanent magnets.

SPIONs Magnetophoresis and Separation via Permanent Magnets: Biomedical and Environmental Applications

“…This reduction in interparticle distance causes an augment in magnetic dipole-dipole interactions, leading to potential particle aggregation when highly concentrated SPION solutions are used. Indeed, it has been recently shown that, through batch separation experiments of 20 nm and 30 nm SPIONs at various initial concentration values of the particle dispersion, higher initial concentrations of SPIONs enhanced the magnetophoretic separation time [63]. However, for an optimal operation of this principle, one must consider the economic viability of the process, since highly concentrated solutions can be detrimental to the process economy and become environmentally non-friendly.…”