Elucidation of the Physicochemical Properties Ruling the Colloidal Stability of Iron Oxide Nanoparticles under Physiological Conditions

Abstract

Nanotechnology has brought countless novel applications regarding therapeutic, diagnostic, and sensing innovations. In particular, nanoparticle engineering enables the synthesis of nanocrystals with customized physical, chemical, and biological activities, which are generally well validated in vitro. However, when nanoparticles are tested in vivo they often show a disappointing loss of efficacy or increase of toxicity. These phenomena are related to the interaction of the nanoparticle surface with proteins, lipids, and ions present in the blood stream. Herein, we assess the physicochemical properties of an array of iron oxide nanoparticles coated with 15 different biocompatible materials dispersed in physiological aqueous media and human blood plasma. Our findings establish valid criteria for the prediction of the colloidal stability of nanoparticles dispersed in physiological aqueous media and human blood plasma. The criteria are based on the hydrophilicity and the net surface charge of the pristine nanoparticle coating in water dispersion. Hence, the methodology to select the most adequate nanoparticle coating for in vivo studies will be improved.

Controlling human platelet activation with calcium-binding nanoparticles

“…As expected, the zeta potential (ζ) of these IONPs varies strongly depending on the IONPs coating, with citrate-coated IONPs being highly negatively charged (Cit/1-IO = –51.8 ± 0.4 mV and Cit/2-IO = –50.5 ± 0.2 mV), whereas the PEG-IO showed positive charge (+37.6 ± 0.5 mV). These values are in agreement with previously reported ζ values of particles coated with similar compounds and obtained from similar sources [ 17 – 19 ].…”

Whither Magnetic Hyperthermia? A Tentative Roadmap

“…These are generally characterized under random conditions, namely pure water, buffers (often phosphate solutions), etc. A priori well-qualified samples, however, often end up failing in vivo due to a significant loss of efficacy and/or the onset of toxicity [35]. The reasons behind this observation can be diverse: sample contamination, MNPs aggregation, and interfacial interactions with cell membranes or blood components, among others [36].…”

“…The main source of uncertainty here is polydispersity, but in the literature, the "DLS size" is often provided without reporting some relevant measurement conditions like pH or ionic strength, making it difficult to establish the source of polydispersity. The latter could reside in the primary particles and their aggregation due to weak colloidal stability [35], and it has a major impact both on the sample's shelf life and its subsequent use. For example, appropriate and inappropriate MNP manufacturing has been illustrated in the literature by human blood smear tests [36].…”

Alternating current (AC) susceptibility as a particle-focused probe of coating and clustering behaviour in magnetic nanoparticle suspensions

“…To avoid agglomeration, the MNP coating should prevent particle interactions such as magnetic forces between particles, and Van der Waals forces 3 . To promote colloidal stability, particles can be surface-modified with surfactants 4 , natural and synthetic polymers 5 , or biomolecules 6,7 . In addition surface functionalization is used to facilitate binding and internalization of MNPs into cells for cell receptor targeting, or for gene or drug delivery for therapeutic purposes 8,9 .…”