CVD Nanocrystalline Diamond Film Doped with Eu.

This paper submits experimental results of a study directed towards the formation of Eu ions' luminescent centers in CVD diamond films. A new approach is based on use of diamond nanoparticles with a surface modified with Eu ions for seeding at CVD growth. Nanocrystalline diamond films (NCD) doped with Eu have been grown from the gas phase on silicon substrates by microwave plasma-assisted CVD at a frequency of 2.45 GHz. The photoluminescence spectra clearly show several electronic transitions of the Eu3+ ions, which confirm the incorporation of Eu ions into the NCD film.

Development of Submicrocapsules Based on Co-Assembled Like-Charged Silica Nanoparticles and Detonation Nanodiamonds and Polyelectrolyte Layers.

Capsules with shells based on nanoparticles of different nature co-assembled at the interface of liquid phases of emulsion are promising carriers of lipophilic drugs. To obtain such capsules, theoretically using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and experimentally using dynamic light-scattering (DLS) and transmission electron microscopy (TEM) methods, the interaction of like-charged silica nanoparticles and detonation nanodiamonds in an aqueous solution was studied and their ratios selected for the formation of submicron-sized colloidosomes. The resulting colloidosomes were modified with additional layers of nanoparticles and polyelectrolytes, applying LbL technology. As a model anti-cancer drug, thymoquinone was loaded into the developed capsules, demonstrating a significant delay of the release as a result of colloidosome surface modification. Fluorescence flow cytometry and confocal laser scanning microscopy showed efficient internalization of the capsules by MCF7 cancer cells. The obtained results demonstrated a high potential for nanomedicine application in the field of the drug-delivery system development.

PVP-coated Gd-grafted nanodiamonds as a novel and potentially safer contrast agent for in vivo MRI.

PURPOSE: Testing the potential use of saline suspension of polyvinylpyrrolidone (PVP)-coated gadolinium(Gd)-grafted detonation nanodiamonds (DND) as a novel contrast agent in MRI. METHODS: Stable saline suspensions of highly purified de-agglomerated Gd-grafted DND particles coated by a PVP protective shell were prepared. T1 and T2 proton relaxivities of the suspensions with varying gadolinium concentration were measured at 8 Tesla. A series of ex vivo (phantom) and in vivo dynamic scans were obtained in 3 Tesla MRI using PVP-coated Gd-grafted DND and gadoterate meglumin in equal concentrations of gadolinium, and then T1 -weighted hyperintensity was compared. RESULTS: The proton relaxivities of PVP-coated Gd-grafted DND were found to be r1 = 15.9 ± 0.8 s-1 mM-1 and r2 = 262 ± 15 s-1 mM-1 , respectively, which are somewhat less than those for uncoated Gd-grafted DND but still high enough. Ex vivo MRI evaluation of PVP-coated Gd-grafted DND results with a dose-dependent T1 -weighted hyperintensity with a significant advantage over the same for gadoterate meglumin. The same was found when the 2 contrast agents were tested in vivo. CONCLUSION: The novel MRI contrast agent - saline suspensions of PVP-coated Gd-grafted DND - provides significantly higher signal intensities than the common tracer gadoterate meglumin, therefore increasing its potential for a safer use in clinics.

Examining relaxivities in suspensions of nanodiamonds grafted by magnetic entities: comparison of two approaches.

OBJECTIVES: Detonation nanodiamonds (DND) with Gd3+ ions directly grafted to the DND surface have recently demonstrated enhanced relaxivity for protons in aqueous suspensions. Herewith, the relaxivity measurements were done on a series of suspensions with the gadolinium content varied by changing number of Gd3+ ions grafted per each DND particle whereas the DND content in each suspension was kept the same. Such an approach to vary the contrast agent content differs from that commonly used in the relaxivity measurements. In the common approach, contrast agents are directly dissolved/suspended in media. Aiming to test validity of the unconventional approach, in the present study we follow the common way of measurement relaxivity: using variable concentrations of carriers (DND particles) in aqueous suspension keeping the number of Gd3+ ions per each carrier fixed. MATERIALS AND METHODS: 1H NMR relaxation measurements of aqueous suspensions of DND with Gd3+ ions directly grafted to the DND surface were carried out at room temperature (293 K or 20 °C) in the external magnetic field B0 = 8.0 T. RESULTS AND CONCLUSIONS: Comparative study of two approaches for measuring relaxivity in suspensions containing DND as magnetic entities' carriers reveals complete identity of techniques in use.