Magnetic particle spectroscopy for monitoring the cellular uptake of magnetic nanoparticles: Impact of the excitation field amplitude

Abstract

Magnetic particle spectroscopy (MPS) is a sensitive method for the quantification of magnetic nanoparticles (MNP). MPS is based on the detection of nonlinear magnetic AC susceptibility and has been established as a rapid and straightforward method for tracer characterization. MPS is also excellent for monitoring the uptake of MNP by cells. The magnetic excitation fields of several millitesla used in MPS measurement raises the possibility of field-induced changes in the MNP sample (e.g., chain formation, aggregation, etc.). In this work, we aim to investigate the field-induced changes in monitoring the uptake of different MNP by THP-1 cells. By using different excitation field amplitudes and measurement scripts, the influence of dynamic magnetic fields on the MPS signal of MNP is investigated and recommendations for continuous MPS measurements of MNP in biological environment are given. We found that the excitation field amplitude and field exposure time can impact the uptake kinetics and influences the temporal resolution. In addition, high SNR can be achieved with a field strength of 12 mT, while at the same time reducing excitation field changes occurring at higher field strengths (such as 25 mT).