I. I. Kulakova

Surface chemistry of nanodiamonds

The experimental data available in the literature and the results obtained by the author in research into the structure of nanodiamonds and the physicochemical and chemical properties of their surface are generalized. An account is given of the problems concerning the chemical state and modification of the nanodiamond surface in gaseous and liquid media and the infiuence of modification on the sorption and catalytic properties of nanodiamonds, their compactibility, and sintering. The similarity and difference in the behavior of nanodiamonds and diamond macrocrystals in oxidation processes are discussed. The activation energies of oxidation of nanodiamonds by different reagents are determined in the absence and presence of catalysts.

Giant dielectric permittivity of detonation-produced nanodiamond is caused by water

We show that small (≤4%) amounts of water which detonation-produced nano-diamond powder always adsorbs spontaneously from air can increase its dielectric permittivity (e) at low frequencies from single digits to over 1019, by far the highest value observed for any system including ferroelectrics. Conversely, traces of DND drastically affect the physical properties of water, increasing its e from ∼80 to over 106 and altering sound velocity. The effect is due to proton-releasing functional groups on the diamond surface interacting with the adsorbed water monolayer, hence it does not occur in hydrogen-free DND. The observed giant dielectric permittivity makes DND a prospective material for high-performance capacitors for use in microelectronics, and for the development of large-scale capacitance-based energy-storage devices urgently demanded in the quest for green energy technology. The results are also relevant for biomedical applications of DND and for understanding the enigmatic surface conductivity of diamond and electrical spectroscopy of porous rocks, which is important in geology.

Effect of detonation nanodiamonds on phagocyte activity.

Detonation ND (nanodiamond) holds much promise for biological studies and medical applications. Properties like size of particles, inclination for modification of their surface and unambiguous biocompatibility are crucial. Of prime importance is interaction between ND and immune cells, which supervise foreign intrusion into an organism and eliminate it. Neutrophils are more reactive in inflammatory response implementing cytotoxical arsenal including ROS (reactive oxygen species). The aim of the work was to estimate the ability of two ND samples (produced by Diamond Center and PlasmaChem) to keep the vitality of neutrophils from the inflammatory site. The ability of cells to generate ROS in the presence of ND particles is considered as indicating their biocompatibility. IR spectra and size of particles in the samples were characterized. Acid modification of ND was carried out to get the luminescent form. In the biological aspect, ND demonstrated up or down action, depending on the concentration, time and conditions of activation of cells. Weak action of ND in whole blood was obtained possibly owing to the ND adsorbed plasma proteins, which mask active functional groups to interact with the cell membrane. ND did not influence the viability of isolated inflammatory neutrophils in low and moderate concentrations and suppressed it in high concentrations (≥1 g/l). Addition of ND to the cell suspension initiated concentration‐dependent reaction to produce ROS similar to respiratory burst. ND up‐regulated response to bacterial formylpeptide, but up‐ and down‐modified (low or high concentrations, accordingly) response to such bacterial agents as OZ (opsonized zymosan), which neutrophils swallow up by oxygen‐dependent phagocytosis. Localization of the particles on the cell surface as into the cells was identified by monitoring the intrinsic fluorescence of oxidized ND. The various mechanisms that could account for penetration of ND particles into the cell are discussed. Common conclusion concerns compatibility of ND with living neutrophils from inflammatory site and their normal functioning for infection safeguard.

The structure of chemically modified detonation-synthesized nanodiamond particles

The results of studies of the structure of chemically modified detonation-synthesized nanodiamond (ND) particles by a set of physical and chemical methods are reported. It is shown that the crystal structure, size, and the paramagnetic properties of the particles persist during chemical modification processes. No nondiamond sp2 carbon is observed in the composition of the particles. The first experimental evidence for the uniform distribution of nitrogen impurities in the detonation-synthesized nanodiamond particles is presented.

Purification and Functionalization of Nanodiamond

This paper briefly discusses the advantages of commercial nanodiamond and analyses its structural and chemical impurities, polyfunctional surface termination, agglomeration, and other features that may restrict the ND application in academic research and industrial practice. We have designed and tested a novel approach to detonation nanodiamond purification and surface functionalization, using a high temperature treatment in gaseous media containing hydrogen and chlorine. A drastic change in the hydrophily (by a factor of 20) due to thermal treatment at 450’C in a CC14/Ar mixture is demonstrated. The characterization techniques employed (chemical analyses; Raman, FTIR, and ESR spectroscopy; chromatomass spectrometry) can provide a profound nanodiamond modification and its prescribed functionalization.

Catalytic conversion of C(2)-C(3) alcohols on detonation nanodiamond and its modifications

The catalytic activity of detonation nanodiamond and its modifications obtained through treatment with hydrogen or air at elevated temperatures is studied in the conversion of C2-C3 alcohols. The catalysts were characterized by means of electron microscopy, optical (FTIR) spectroscopy, elemental analysis and pulse microcatalytic method. It has been established that nanodiamond exhibits high catalytic activity in the conversion of alcohols. The oxidizing and reducing treatment of nanodiamond changes its activity and selectivity, and the activity of oxidized nanodiamond is considerably higher than that of reduced nanodiamond.

Comparative X-ray absorption investigation of fluorinated single-walled carbon nanotubes

The C 1s and F 1s X-ray absorption spectra of pristine and fluorinated single-walled carbon nanotubes with different fluorine contents and nanodiamond as a reference compound have been measured with the aim of characterizing single-walled carbon nanotubes and their products formed upon treatment of the nanotubes with molecular fluorine at a temperature of 190°C. The spectra obtained have been analyzed by thoroughly comparing with the previously measured spectra of highly oriented pyrolytic graphite and fluorinated multiwalled carbon nanotubes and the spectrum of nanodiamond. It has been established that the fluorination of single-walled and multiwalled carbon nanotubes leads to similar results and is characterized by the attachment of fluorine atoms to carbon atoms on the lateral surface of the nanotube with the formation of the σ(C-F) bonds due to the covalent mixing of F 2p and C 2pz π valence electron states.

Detonation diamond—A perspective carrier for drug delivery systems

Analysis of published and author’s own experimental data provides convincing evidence for the theoretical possibility to create drug delivery systems on the basis of detonation nanodiamonds and for the promise such systems hold for commercialization and practical application.

IR spectra of detonation nanodiamonds modified during the synthesis

IR-spectra of a great number of samples of detonation nanodiamonds (DND) obtained under different conditions (with dopants added or with the use of reducing agents) have been analyzed for the first time. The quantity and type of incombustible impurities have been found to have no effect on the pattern of IR spectra. It is shown that in the IR-spectral range there exist some narrow frequency ranges where the majority of DND exhibit absorption regardless of the synthesis conditions (829, 1365, 1558, 1628, 1732, 2341, 2858, 2928 cm−1). IR-spectra confirm the presence of nitrogen impurity centers in new DNDs and of the functional groups NO2, CH, NO3, CH2, OH, C=O on the DND surface.

Effect of the Detonation Nanodiamond Surface on the Catalytic Activity of Deposited Nickel Catalysts in the Hydrogenation of Acetylene

A comparative study is performed of the catalytic activity of nanosized nickel deposited on detonation synthesis nanodiamond (DND) and coal (CSUG) produced by burning sugar and crystalline quartz in the hydrogenation of acetylene. Nanosized nickel is obtained through the thermal decomposition of nickel formate under a dynamic vacuum. The catalysts are studied by means of scanning electron and transmission electron microscopy, X-ray fluorescence, IR-spectroscopy, X-ray diffraction, and pulse microcatalytic method. It is shown that Ni/DND is an active catalyst of acetylene hydrogenation, considerably surpassing Ni/quartz and Ni/CSUG. The apparent activation energy of the hydrogenation of acetylene is calculated, and the region of the reaction are determined for all catalysts. It is found that the influence of the structure and nature of a functional coating of nanodiamond on the catalytic activity of Ni/DND deposited catalyst in the hydrogenation of acetylene. The ability of Ni/DND to hold active hydrogen is detected.