Unmodified Nanodiamonds Research Articles

Biomolecular Adsorption to Interfacial Single Particle Layer of Organo-Modified Nanodiamond and Its Second-Order Structure.

Modifying the surface of nanodiamonds, which have antibacterial properties, with organic molecular chains enables biomolecular adsorption on a single particle layer on the water surface. For organo-modification, long-chain fatty acids act on the terminal hydroxyl groups present on the nanodiamond surface, and cytochrome C protein and trypsin enzyme are used as biomolecules. Cytochrome C and trypsin introduced into the subphase were electrostatically adsorbed onto the unmodified hydrophilic surface of the organo-modified nanodiamond monolayers on the water surface. The ampholyte protein is thought to exhibit Coulomb interactions with the positively charged unmodified nanodiamond surface. The protein adsorption was supported by morphological observations and spectroscopic properties; circular dichroism spectra suggested denaturation of the adsorbed proteins. However, the biopolymers could maintain their second-order structure even under a high-temperature environment, after being slightly denatured and adsorbed to the template. The nanodiamonds form excellent templates for structural retention in the atmosphere while yielding minor denaturation corresponding to the chirality of biomolecules upon adsorption.

Efficient removal of heavy metal ions from aqueous media by unmodified and modified nanodiamonds

This article deals with the adsorption performances of the unmodified nanodiamond (ND) and thermally oxidized nanodiamond (Ox-ND) for the removal of different heavy metal ions such as Fe (III), Cu (II), Cr (VI), and Cd (II) from wastewater. The adsorption capacities of the ions onto adsorbents are higher and follow the order: Ox-ND-3 > Ox-ND-1.5 > ND, which is consistent with their surface areas, zeta potentials, and the presence of carboxyl groups, suggesting that electrostatic attractions between the positive metal ions and the negatively charged adsorbents are the predominant adsorption mechanisms. Adsorption capacities of these adsorbents were found to be 26.8, 31.3, and 45.7 mg/g for Fe (III), 25.2, 30.5, and 44.5 mg/g for Cu (II), 33.6, 44.1, and 55.9 mg/g for Cr (VI), and 40.9, 52.9, and 67.9 mg/g for Cd (II) over ND, Ox-ND-1.5, and Ox-ND-3, respectively. The impact of various operating parameters such as agitation time, initial metal ion concentration, temperature, pH solution, adsorbent dosage, and coexistence of the metal ions on the adsorption performance of Ox-ND-3 towards Cd (II) ions along with the batch adsorption experiments were performed. The equilibrium was reached in 120 min and adsorption data were fitted well with the pseudo-second-order kinetic as well as the Freundlich isotherm models. Adsorption process was spontaneous and exothermic, while the maximum removal efficiency of Cd (II) ions occurred at pH of 6.9 and at 4 g/L dosage. These findings demonstrated that thermally oxidized nanodiamond (Ox-ND) can be a versatile adsorbent to remove the Cd (II) ions from wastewater.

Icariin-Functionalized Nanodiamonds to Enhance Osteogenic Capacity In Vitro.

Nanodiamonds (NDs) have been used as drug delivery vehicles due to their low toxicity and biocompatibility. Recently, it has been reported that NDs have also osteogenic differentiation capacity. However, their capacity using NDs alone is not enough. To significantly improve their osteogenic activity, we developed icariin (ICA)-functionalized NDs (ICA-NDs) and evaluated whether ICA-NDs enhance their in vitro osteogenic capacity. Unmodified NDs and ICA-NDs showed nanosized particles that were spherical in shape. The ICA-NDs achieved a prolonged ICA release for up to 4 weeks. The osteogenic capacities of NDs, ICA (10 μg)-NDs, and ICA (50 μg)-NDs were demonstrated by alkaline phosphatase (ALP) activity; calcium content; and mRNA gene levels of osteogenic-related markers, including ALP, runt-related transcript factor 2 (RUNX2), collagen type I alpha 1 (COL1A1), and osteopontin (OPN). In vitro cell studies revealed that ICA (50 μg)-ND-treated MC3T3-E1 cells greatly increased osteogenic markers, including ALP, calcium content, and mRNA gene levels of osteogenic-related markers, including ALP, RUNX2, COL1A1, and OPN compared to ICA (10 μg)-NDs or ND-treated cells. These our data suggest that ICA-NDs can promote osteogenic capacity.

Cинтез сверхтвердых материалов на основе сфалеритного нитрида бора с применением наночастиц углерода в качестве катализатора фазового превращения

Using modern ideas about the form of the phase diagram of boron nitride, the paper considers thermodynamic parameters and mechanisms of the synthesis of dense phases of boron nitride under equilibrium and nonequilibrium conditions. It has been verified that nanodiamonds, like fullerenes and carbon nanotubes, have catalytic properties and contribute to the solid-state conversion of graphite-like boron nitride to sphalerite modification at high pressures and temperatures. We propose a mechanism for the interaction of nanodiamond under high pressures with the surface of graphite-like boron nitride, which leads to a change in the type of electronic bond in its lattice from sp2 to sp3 with the formation of boron nitride with a wurtzite structure and its subsequent transformation into sphalerite boron nitride by the shear mechanism. The use of carbon-coated nanodiamonds resulted in an increase in the catalytically active centers of phase transformation in boron nitride in comparison with unmodified nanodiamonds, which was manifested in an increase in the content of sphalerite boron nitride in materials obtained under comparable technological synthesis conditions. Modified nanodiamonds also contribute to the intensification of the synthesis of superhard polycrystals as compared to uncoated nanodiamond additives, both due to the diffusion of carbon atoms along the grain boundaries of sphalerite boron nitride and due to the rearrangement of graphite microgroups into a diamond structure and sintering of the obtained diamond blocks with grains of sphalerite boron nitride. The process parameters of obtaining superhard polycrystals based on sphalerite boron nitride with the addition of detonation nanodiamond powders after chemical cleaning and surface modification with non-diamond forms of carbon were found.

Material‐related losses of natural rubber composites with surface‐modified nanodiamonds

ABSTRACTDielectric elastomer generators (DEGs) offer a solution for the growing sustainable energy needs. Despite the active research on DEGs, currently used materials do not possess the required properties to achieve the full potential performance of such generators, thus, limiting an economical attractiveness of DEGs. Therefore, tailor‐made materials for DEGs are in demand. Customizing the natural rubber recipe allows both dielectric and mechanical loss reduction, while the addition of nanodiamonds lowers the stress relaxation and hysteresis loss even further. The effect is most pronounced after chemical modification of nanodiamonds with silane coupling agents. Moreover, such modified nanodiamonds show less dielectric losses compared to unmodified nanodiamonds and allow reducing the dynamic loss tangent of the compound. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48629.

Correlation between the catalytic and electrocatalytic properties of nitrogen-doped carbon nanoonions and the polarity of the carbon surface: Experimental and theoretical investigations

Nitrogen atoms were introduced into carbon nanoonion (CNO) cages by annealing aminated nanodiamonds (AM-NDs) under an inert helium atmosphere and reduced pressure. This procedure provided a convenient tool to control the surface properties, such as polarity, and to make CNOs suitable for various applications. Two series of CNOs were produced using different temperatures (1150, 1450 and 1650 °C) and starting materials, unmodified nanodiamonds (NDs) and AM-NDs. Nitrogen-doped CNOs (NCNOs) were prepared by annealing AM-NDs at 1150 °C via a procedure previously reported by our group. Herein, the surface polarity of the NCNOs and their catalytic and electrocatalytic properties were compared with those of the pristine CNOs obtained from non-functionalized NDs under the same experimental conditions. For these purposes, we used several experimental and theoretical methods, such as X-ray photoelectron spectroscopy, water adsorption-desorption measurements supported by the model proposed by Dubinin and Serpinsky, catalytic tests with a gasometric method and electrochemical studies, including cyclic voltammetry and amperometry. All of the CNOs and NCNOs were evaluated for use as biocompatible mediator-free substrates for horseradish peroxidase in hydrogen peroxide detection.

Characterization of Nanodiamond-based anti-HIV drug Delivery to the Brain

Human Immunodeficiency Virus Type 1 (HIV-1) remains one of the leading causes of death worldwide. Present combination antiretroviral therapy has substantially improved HIV-1 related pathology. However, delivery of therapeutic agents to the HIV reservoir organ like Central nervous system (CNS) remains a major challenge primarily due to the ineffective transmigration of drugs through Blood Brain Barrier (BBB). The recent advent of nanomedicine-based drug delivery has stimulated the development of innovative systems for drug delivery. In this regard, particular focus has been given to nanodiamond due to its natural biocompatibility and non-toxic nature–making it a more efficient drug carrier than other carbon-based materials. Considering its potential and importance, we have characterized unmodified and surface-modified (-COOH and -NH2) nanodiamond for its capacity to load the anti-HIV-1 drug efavirenz and cytotoxicity, in vitro. Overall, our study has established that unmodified nanodiamond conjugated drug formulation has significantly higher drug loading capacity than surface-modified nanodiamond with minimum toxicity. Further, this nanodrug formulation was characterized by its drug dissolution profile, transmigration through the BBB, and its therapeutic efficacy. The present biological characterizations provide a foundation for further study of in-vivo pharmacokinetics and pharmacodynamics of nanodiamond-based anti-HIV drugs.

Direct surface PEGylation of nanodiamond via RAFT polymerization

Nanodiamond (ND) is a novel class of carbon nanomaterials, which has been extensively investigated for biomedical applications because of its small size, high surface area and excellent biocompatibility. However, the biomedical applications of unmodified ND are still largely restricted because of their poor dispersibility in both aqueous and organic medium. In this work, we reported a novel strategy for the surface modification of ND via reversible addition fragmentation chain transfer (RAFT) polymerization. For preparation of the PEGylated ND (pPEGMA-ND), chain transfer agent (CTA) was immobilized onto ND through reaction between the hydroxyl group of ND and the carboxyl group of CTA, which was used as the initiator for surface-initiated RAFT polymerization. The successful preparation of pPEGMA-ND was characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectra and thermal gravimetric analysis in detail. Results demonstrated that pPEGMA-ND exhibited enhanced water dispersibility and desirable biocompatibility, making it promising for biomedical applications.

Effect of functionalized and non-functionalized nanodiamond on the morphology and activities of antioxidant enzymes of lung epithelial cells (A549)

The development of nanotechnology opens up new ways for biomedical applications of unmodified and modified diamond nanoparticles which are one of the most popular nanomaterials used in biology, biotechnology, medicine, cosmetics and engineering. They have been applied as diagnostic and therapeutic agents because they can be targeted to and localized in cells causing apoptosis and necrosis. The problem of biocompatibility of nanodiamonds at higher concentrations is thus of primary importance. The first step in the modification of DNPs is usually the introduction of hydrogen groups, which can bind other functional groups. The basic method to introduce –OH groups onto nanoparticles is the Fenton reaction. The aim of this study was to compare the effect of unmodified nanodiamond particles and nanoparticles modified by introduction of –OH groups and etoposide onto their surface reaction on human non-small lung cancer cells. A549 cells were incubated with 2–100μg/ml nanopowders and at 0.6–24μg/ml etoposide in the DMEM medium. We observed a decrease of cells viability and generation of reactive oxygen/ nitrogen species in the cells after incubation, estimated by oxidation of H2DCF-DA and DAF-FM-DA. Modified detonation nanoparticles affected also the cellular content of glutathione and activities of main antioxidant enzymes (glutathione peroxidase, glutathione reductase, glutathione S-transferase, superoxide dismutase and catalase). The results of TEM microscopy show changes in cell morphology. These data demonstrate that modified nanoparticles induce oxidative stress in the target cells.

Enhanced gas-sensing by diamond nanoneedle arrays formed by reactive ion etching

Vertically aligned diamond nanoneedles were fabricated on nanocrystalline diamond (NCD) films by reactive ion etching (RIE), in which diamond nanoparticles ∼10nm in diameter seeded on the nanodiamond film to serve as an etching mask. The sensing ability of the elaborated diamond nanoneedle arrays was measured at room temperature with NH3 and NO2 diluted in air. The results showed that the diamond nanoneedle arrays had a greatly enhanced chemical sensing ability compared with the unmodified nanodiamond films, mainly due to the increased surface area-to-volume ratio and nanotip effect of the diamond nanoneedles. In addition, the diamond nanoneedle arrays evidenced different gas sensing processes when exposed to reducing and oxidizing gases, in which the direction of electron transport plays an important role.

Resorcinarene amine stabilized nanodiamond dispersions in organic solvents: applications in diamond film growth

Nanodiamonds of widely differing sizes (4 to >100 nm), shapes, and origin could be extracted from aqueous dispersions into toluene by a multidentate resorcinarene amine surfactant, in the absence of any elaborate covalent functionalization or extreme conditions. Resorcinarene amine encapsulated nanodiamonds displayed excellent dispersion stability in non-polar organic solvents for several months. The IR spectral analysis of these extracted and further precipitated nanodiamonds suggests that the carboxylic acid groups present on the nanodiamond surfaces are electrostatically stabilized by the resorcinarene amine surfactant. Such nanodiamond dispersions can also act as nucleation sources for the fabrication of continuous diamond films by CVD growth. Notably, this process resulted in diamond films with better uniformity, smaller grain size and reduced surface roughness when compared to the films prepared with unmodified nanodiamonds as nucleating agents.