Smart nanoparticles for medical applications have gathered considerable attention due to an improved biocompatibility and multifunctional properties useful in several applications, including advanced drug delivery systems, nanotheranostics and in vivo imaging. Among nanomaterials, zinc oxide nanoparticles (ZnO NPs) were deeply investigated due to their peculiar physical and chemical properties. The large surface to volume ratio, coupled with a reduced size, antimicrobial activity, photocatalytic and semiconducting properties, allowed the use of ZnO NPs as anticancer drugs in new generation physical therapies, nanoantibiotics and osteoinductive agents for bone tissue regeneration. However, ZnO NPs also show a limited stability in biological environments and unpredictable cytotoxic effects thereof. To overcome the abovementioned limitations and further extend the use of ZnO NPs in nanomedicine, doping seems to represent a promising solution. This review covers the main achievements in the use of doped ZnO NPs for nanomedicine applications. Sol-gel, as well as hydrothermal and combustion methods are largely employed to prepare ZnO NPs doped with rare earth and transition metal elements. For both dopant typologies, biomedical applications were demonstrated, such as enhanced antimicrobial activities and contrast imaging properties, along with an improved biocompatibility and stability of the colloidal ZnO NPs in biological media. The obtained results confirm that the doping of ZnO NPs represents a valuable tool to improve the corresponding biomedical properties with respect to the undoped counterpart, and also suggest that a new application of ZnO NPs in nanomedicine can be envisioned.

Doped Zinc Oxide Nanoparticles: Synthesis, Characterization and Potential Use in Nanomedicine.

Highly sensitive and selective ethanol and acetone gas sensors based on modified ZnO nanomaterials

The interplay between morphology and photocatalytic activity in ZnO and N-doped ZnO crystals

Structural, microstructural, optical and magnetic properties of Mn-doped ZnO nanostructures

Effect of Mn doping concentration on structural, vibrational and magnetic properties of NiO nanoparticles

Mn-doped ZnO nanocrystals were successfully prepared using a novel sol–gel method followed by drying in autoclave under supercritical conditions. The estimated crystallite size is in the range of 30–50 nm, in agreement with TEM analysis. Rietveld refinements confirm the formation of pure Mn-doped ZnO for lower Mn concentration. i.e. less than 5%. The lattice parameters increase with increasing Mn content according to Vegard's law due to the larger ionic radius of Mn2+ compared to that of Zn2+. Magnetic analysis reveals that increasing the doping level of Mn above 2% is not helping the long range ferromagnetic order in the sample but only enhancing the paramagnetic component. The paramagnetic susceptibility is found to increase linearly with increasing Mn concentration which suggests the formation of uncoupled magnetic moment. The estimated values for the magnetic moment per Mn atom are found to be in the range of 2–3.5 µB/Mn. Ab-initio calculations also have been performed which showed that doping diamagnetic bulk ZnO with Mn induces ferromagnetic at room temperature, the total magnetic momentum increases with increasing Mn content whereas the magnetic moment of Mn is predicted to be in the range of 3–3.5 μB/Mn atom which is consistent with the values obtained from magnetic measurements.

Structural and magnetic properties of Mn-doped ZnO nanocrystals

By ab-initio calculations on Zn0.95−x
 Co0.05Cu
 x
 O, we study the variations of magnetic moments versus Cu concentration. The electronic structure is calculated by using the Korringa–Kohn–Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that the total magnetic moment and magnetic moment of Co increase with increasing Cu content. From a density of state (DOS) analysis, we propose an explanation of the enhancement of the Co magnetic moment versus Cu concentration.

Explanation of Co Magnetic Moment Enhancement in (Co,Cu)-Doped ZnO by First-Principle Calculations

By ab-initio calculations, the possible source of ferromagnetism in N-doped ZnO compound was systematically studied. The electronic structure and magnetic properties of N-doped ZnO with/without ZnO host and N defects were investigated using the Korringa–Kohn–Rostoker method combined with coherent potential approximation. It was shown that Zn vacancy and the presence of N defects (substitutional, interstitial or combination of both) induce the ferromagnetism in N-doped ZnO. From density of state analysis, it was shown that p–p interaction between 2p-elements (N,O) is the mechanism of ferromagnetic coupling in N-doped ZnO.

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Explanation of ferromagnetism origin in N-doped ZnO by first-principle calculations

Using ab initio calculations on Zn0.975−
 x
 Fe0.025Cu
 x
 O (x = 0, 0.01, 0.02, 0.05), we study the variations of magnetic moments vs Cu concentration. The electronic structure is calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that the total magnetic moment and magnetic moment of Fe increase on increasing Cu content. From the density of state (DOS) analysis, we show that Cu-induced impurity bands can assure, by two mechanisms, the enhancement of Fe magnetic moment in Zn0.975−
 x
 Fe0.025Cu
 x
 O.

/pdf/study-of-cu-doping-effects-on-magnetic-properties-of-fe-3j147lx8jo.pdf

A. El Amiri

Papers

Structural and magnetic properties of Mn-doped ZnO nanocrystals

Explanation of Co Magnetic Moment Enhancement in (Co,Cu)-Doped ZnO by First-Principle Calculations

Explanation of ferromagnetism origin in N-doped ZnO by first-principle calculations

Study of Cu-doping effects on magnetic properties of Fe-doped ZnO by first principle calculations