A CE-ICP-MS/MS method for the determination of superparamagnetic iron oxide nanoparticles under simulated physiological conditions.

Over the past few years, superparamagnetic iron oxide nanoparticles (SPIONs) have attracted much attention due to their medicinally attractive properties and their possible application in cancer diagnosis and therapy. However, there is still a lack of appropriate methods to enable quantitative monitoring of the particle changes in a physiological environment, which could be beneficial for evaluating their in vitro and in vivo behavior. For this reason, the main goal of this study was the development of a novel capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS/MS) method for the determination of SPIONs suitable for the future examination of their changes upon incubation with proteins under simulated physiological conditions. The type and flow rate of the collision/reaction gas were chosen with the aim of simultaneous monitoring of Fe and S. The type and concentration of the background electrolyte, applied voltage, and sample loading were optimized to obtain SPION signals of the highest intensity and minimum half-width of the peak. Analytical parameters were at a satisfactory level: reproducibility (intra- and inter-day) of migration times and peak areas (presented as RSD) in the range of 0.23-4.98%, recovery: 96.7% and 93.3%, the limit of detection (for monitoring FeO by mass-shift approach) 54 ng mL Fe (0.97 μM) and 101 ng mL Fe (1.82 μM) for SPIONs with carboxyl and amino terminal groups, respectively. To the best of our knowledge, this is the first reported use of CE-ICP-MS/MS for the quantification of SPIONs and monitoring of interactions with proteins.