Nanocrystals of Zn(Fe)O-based diluted magnetic semi-conductor as potential luminescent and magnetic bimodal bioimaging probes

Abstract

Nanocrystals of Zn(Fe)O-based diluted magnetic semi-conductor (nanoDMS) have been prepared by forced hydrolysis in polyol medium, using zinc and iron salts, and coated with carboxymethylpullulan (CMP). TEM studies revealed that CMP-nanoDMS are spherical, with average diameters on the order of 20 nm. Hydrodynamic diameters of about 75 nm were found in a physiological medium. NanoDMS were superparamagnetic at body temperature, and exhibited high saturation magnetization values (3.25 emu g⁻¹). In aqueous suspensions, the colloids revealed high transverse proton relaxivities (T₂) with an r₂ value of 203 mM⁻¹ s⁻¹ (300 K, 1.41 T). Visible photoluminescent properties were evidenced with an excitation wavelength of 366 nm. No evidence of cell toxicity was found for human endothelial cells incubated with CMP-nanoDMS, at concentrations up to 100 μg mL⁻¹ and for 48 h. No modification to the cytoskeleton was found up to 6 days of exposure. These hybrid nanomaterials could be considered as novel potential MR and luminescent bioimaging agents.