Assessing cell-nanoparticle interactions by high content imaging of biocompatible iron oxide nanoparticles as potential contrast agents for magnetic resonance imaging.

Stem cell tracking in cellular therapy and regenerative medicine is an urgent need, superparamagnetic iron oxide nanoparticles (IONPs) could be used as contrast agents in magnetic resonance imaging (MRI) that allows visualization of the implanted cells ensuring they reach the desired sites in vivo. Herein, we report the study of the interaction of 3,4-dihydroxyhydrocinnamic acid (DHCA) functionalized IONPs that have desirable properties for T2 - weighted MRI, with bone marrow-derived primary human mesenchymal stem cells (hMSCs). Using the multiparametric high-content imaging method, we evaluate cell viability, formation of reactive oxygen species, mitochondrial health, as well as cell morphology and determine that the hMSCs are minimally affected after labelling with IONPs. Their cellular uptake is visualized by transmission electron microscopy (TEM) and Prussian Blue staining, and quantified using an iron specific colourimetric method. In vitro and in vivo studies demonstrate that these IONPs are biocompatible and can produce significant contrast enhancement in T2-weighted MRI. Iron oxide nanoparticles are detected in vivo as hypointense regions in the liver up to two weeks post injection using 9.4 T MRI. These DHCA functionalized IONPs are promising contrast agents for stem cell tracking by T2-weighted MRI as they are biocompatible and show no evidence of cytotoxic effects on hMSCs.

Correction: High magnetisation, monodisperse and water-dispersible CoFe@Pt core/shell nanoparticles.

Correction for 'High magnetisation, monodisperse and water-dispersible CoFe@Pt core/shell nanoparticles' by Ngo T. Dung et al., Nanoscale, 2017, DOI: 10.1039/c6nr09325f.

High magnetisation, monodisperse and water-dispersible CoFe@Pt core/shell nanoparticles.

High magnetisation and monodisperse CoFe alloy nanoparticles are desired for a wide range of biomedical applications. However, these CoFe nanoparticles are prone to oxidation, resulting in the deterioration of their magnetic properties. In the current work, CoFe alloy nanoparticles were prepared by thermal decomposition of cobalt and iron carbonyls in organic solvents at high temperatures. Using a seeded growth method, we successfully synthesised chemically stable CoFe@Pt core/shell nanostructures. The obtained core/shell nanoparticles have high saturation magnetisation up to 135 emu g-1. The magnetisation value of the core/shell nanoparticles remains 93 emu g-1 after being exposed to air for 12 weeks. Hydrophobic CoFe@Pt nanoparticles were rendered water-dispersible by encapsulating with poly(maleic anhydride-alt-1-octadecene) (PMAO). These nanoparticles were stable in water for at least 3 months and in a wide range of pH from 2 to 11.

Synthesis of magnetic cobalt ferrite nanoparticles with controlled morphology, monodispersity and composition: the influence of solvent, surfactant, reductant and synthetic conditions.

In our present work, magnetic cobalt ferrite (CoFe2O4) nanoparticles have been successfully synthesised by thermal decomposition of Fe(III) and Co(II) acetylacetonate compounds in organic solvents in the presence of oleic acid (OA)/ oleylamine (OLA) as surfactants and 1,2-hexadecanediol (HDD) or octadecanol (OCD-ol) as an accelerating agent. As a result, CoFe2O4 nanoparticles of different shapes were tightly controlled in size (range of 4-30 nm) and monodispersity (standard deviation only at ca. 5%). Experimental parameters, such as reaction time, temperature, surfactant concentration, solvent, precursor ratio, and accelerating agent, in particular, the role of HDD, OCD-ol, and OA/OLA have been intensively investigated in detail to discover the best conditions for the synthesis of the above magnetic nanoparticles. The obtained nanoparticles have been successfully applied for producing oriented carbon nanotubes (CNTs), and they have potential to be used in biomedical applications.

Synthesis of core-shell gold coated magnetic nanoparticles and their interaction with thiolated DNA.

Core-shell magnetic nanoparticles have received significant attention recently and are actively investigated owing to their large potential for a variety of applications. Here, the synthesis and characterization of bimetallic nanoparticles containing a magnetic core and a gold shell are discussed. The gold shell facilitates, for example, the conjugation of thiolated biological molecules to the surface of the nanoparticles. The composite nanoparticles were produced by the reduction of a gold salt on the surface of pre-formed cobalt or magnetite nanoparticles. The synthesized nanoparticles were characterized using ultraviolet-visible absorption spectroscopy, transmission electron microscopy, energy dispersion X-ray spectroscopy, X-ray diffraction and super-conducting quantum interference device magnetometry. The spectrographic data revealed the simultaneous presence of cobalt and gold in 5.6±0.8 nm alloy nanoparticles, and demonstrated the presence of distinct magnetite and gold phases in 9.2±1.3 nm core-shell magnetic nanoparticles. The cobalt-gold nanoparticles were of similar size to the cobalt seed, while the magnetite-gold nanoparticles were significantly larger than the magnetic seeds, indicating that different processes are responsible for the addition of the gold shell. The effect on the magnetic properties by adding a layer of gold to the cobalt and magnetite nanoparticles was studied. The functionalization of the magnetic nanoparticles is demonstrated through the conjugation of thiolated DNA to the gold shell.

Cobalt nanoparticles as a novel magnetic resonance contrast agent--relaxivities at 1.5 and 3 Tesla.

Two samples of polymer-coated cobalt nanoparticles were synthesized and dispersed in agarose gel and water. The relaxivities r1 and r2 of the two samples were obtained at different temperatures (25, 37 and 40 degrees C) and magnetic field strengths (1.5 and 3 T). The average cobalt core diameters of the two samples were 3.3 and 3.9 nm (measured by transmission electron microscopy); the corresponding average total diameters (cobalt core + polymer coating) were 13 and 28 nm (measured by dynamic light scattering). The larger particles had the higher r1 relaxivity, whilst r2 was similar for the two samples. There was no significant change in r1 or r2 relaxivities with temperature but r1 at 1.5 T was approximately double the value at 3 T. The highest relaxivities were obtained at 1.5 T with values for r1 and r2 of 7.4 and 88 mM(-1) s(-1), respectively. These values are similar to those reported for iron oxide with larger core size, suggesting the potential of the cobalt nanoparticles for development and future use as a negative contrast agent.

One-step synthesis of monodisperse water-soluble 'dual-responsive' magnetic nanoparticles.

Monodisperse water-soluble Co and gamma-Fe(2)O(3) nanoparticles have been prepared in a single-step method using stimuli-sensitive polymers.