Degradability of superparamagnetic nanoparticles in a model of intracellular environment: follow-up of magnetic, structural and chemical properties

Abstract

The unique magnetic properties of iron oxide nanoparticles have paved the way for various biomedical applications, such as magnetic resonance cellular imaging or magnetically induced therapeutic hyperthermia. Living cells interact with nanoparticles by internalizing them within intracellular acidic compartments. Although no acute toxicity of iron oxide nanoparticles has been reported up to now, the mechanisms of nanoparticle degradation by the cellular environment are still unknown. In the organism, the long term integrity and physical state of iron-based nanoparticles are challenged by iron homeostasis. In this study, we monitored the degradation of 7 nm sized maghemite nanoparticles in a medium mimicking the intracellular environment. Magnetic nanoparticles with three distinct surface coatings, currently evaluated as MRI contrast agents, were shown to exhibit different kinetics of dissolution at an acidic pH in the presence of a citrate chelating agent. Our assessment of the physical state of the nanoparticles during degradation revealed that the magnetic properties, size distribution and structure of the remaining nanocrystals were identical to those of the initial suspension. This result suggests a model for nanoparticle degradation with rapidly dissolved nanocrystals and a reservoir of intact nanoparticles.

Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers

“…Once internalized, lyzosome-mediated degradation is generally considered to be the main intracellular metabolic mechanism involved in the degradation of SPIONs. 70,71 In order to evaluate the degradation rate of SPIONs internalized within acidic intracellular components, Arbab et al utilized an in vitro lyzosomal environment containing appropriate and/or specific chelates, such as citrates and phosphates, at an acidic pH. They demonstrated that sodium citrate at pH 4.5 rapidly dissolved ferumoxide, a dextran-coated SPION.…”

Colloidal stability of carboxylated iron oxide nanomagnets for biomedical use

“…The excellent biocompatibility of GA@MNPs explains the necessity of further experiments in the direction of increasing colloidal stability of GA-coated particles, which can be based on the surface catalysed polymerization of GA in the adsorbed state. Some indication can be found in literature regarding the insufficient biocompatibility of citrate-coated MNPs [31,32]. It is likely that some cell toxicity concerns lie behind stopping -at least for the moment -of the clinical trials of VSOP-C184, the only CA@MNP product tested up-to-date.…”

Paracrine signalling of inflammatory cytokines from an in vitro blood brain barrier model upon exposure to polymeric nanoparticles

“…However, polystyrene has been shown to be resistant to thermal oxidation below 200°C, which is far above the viability limit of in vitro biological conditions. [37][38][39] A high level of lysosomal accumulation was associated with a low level of cytokine signalling 24 h post exposure of the BBB monolayer to 100 nm PS COOH NPs. Inflammasome activation due to lysosome signalling is associated with an increase in activated IL1-beta levels, which were not found in this study.…”