Alginate‐coated magnetic nanoparticles for noninvasive MRI of extracellular calcium. (25th April 2014)

• Record Type: Journal Article
• Authors: Bar‐Shir, Amnon; Avram, Liat; Yariv‐Shoushan, Shani; Anaby, Debbie; Cohen, Smadar; Segev‐Amzaleg, Niva; Frenkel, Dan; Sadan, Ofer; Offen, Daniel; Cohen, Yoram
• Is Part Of: NMR in biomedicine. Volume 27:Number 7(2014:Jul.)
• Page Start: 774
• Page End: 783
• Publication Date: 2014-04-25
• Subjects: Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.3117
• Languages: English
• ISSNs: 0952-3480

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Nanoparticles (NPs) have great potential to increase the diagnostic capacity of many imaging modalities. MRI is currently regarded as the method of choice for the imaging of deep tissues, and metal ions, such as calcium ions (Ca<sup>2+</sup>), are essential ingredients for life. Despite the tremendous importance of Ca<sup>2+</sup> for the well‐being of living systems, the noninvasive determination of the changes in Ca<sup>2+</sup> levels in general, and extracellular Ca<sup>2+</sup> levels in particular, in deep tissues remains a challenge. Here, we describe the preparation and contrast mechanism of a flexible easy to prepare and selective superparamagnetic iron oxide (SPIO) NPs for the noninvasive determination of changes in extracellular Ca<sup>2+</sup> levels using conventional MRI. We show that SPIO NPs coated with monodisperse and purified alginate, having a specific molecular weight, provide a tool to selectively determine Ca<sup>2+</sup> concentrations in the range of 250 µ<sc>m</sc> to 2.5 m<sc>m</sc>, even in the presence of competitive ions. The alginate‐coated magnetic NPs (MNPs) aggregate in the presence of Ca<sup>2+</sup>, which, in turn, affects the <italic>T</italic><sub>2</sub> relaxation of the water protons in their vicinity. The new alginate‐coated SPIO NP formulations, which have no effect on cell viability for 24 h, allow the detection of Ca<sup>2+</sup> levels secreted from ischemic cell cultures and the qualitative examination of the change in extracellular Ca<sup>2+</sup> levels <italic>in vivo</italic>. These results demonstrate that alginate‐coated MNPs can be used, at least qualitatively, as a platform for the noninvasive MRI determination of extracellular Ca<sup>2+</sup> levels in myriad <italic>in vitro</italic> and <italic>in vivo</italic> biomedical applications. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>