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Chemical modifications and stability of diamond nanoparticles resolved by infrared spectroscopy and Kelvin force microscopy Nanostructured Materials 2012. Special Issue Editors: Juan Manuel Rojo, Vasileios Koutsos
Abstract and Figures
Chemically modified 5-nm detonation diamond nanoparticles (DNPs) are characterized by grazing angle reflectance (GAR) Fourier transform infrared spectroscopy (FTIR), Kelvin force microscopy (KFM), and X-ray photoelectron spectroscopy (XPS). Using GAR-FTIR we discuss the surface chemistry and stability of the as-received DNPs, and compare them with DNPs modified by annealing in air or by oxygen plasma treatment. Infrared spectra of the as-received DNPs are dominated by C–H bonds and carboxylic groups (COOH), probably related to the wet chemical treatment in acids. Annealing in air and oxygen plasma lead to a significant enhancement of C=O groups and vanishing C–H groups. After short-term (10 min) oxygen plasma treatment, infrared peaks change in intensity and position indicating a spontaneous reactivity of DNPs, probably due to the partial erosion of the graphitic shell. Prolonged oxygen plasma treatment (40 min) or annealing in air at 450 °C for 30 min provides a stable DNPs surface. Surface potentials of DNPs obtained by KFM are well correlated with the GAR-FTIR measurements. XPS characterization corroborates DNPs compositional changes after the modification procedures.
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... There were a few SP 2 C atom bondings on the surface of the ordinary diamonds [27][28][29]. There were more SP 2 C atom bondings on the surface of the porous diamonds. ...
Ordinary diamond presents the disadvantages of poor self-sharpening and concentrated grinding stress when it is used as an abrasive. Moreover, this kind of diamond cannot be well wetted by the vitrified bond, resulting in a lower holding force of the binder to the abrasives (i.e., the diamond is easy to detach from the binder matrix during grinding). These comprehensive factors not only reduce the surface quality of the processed workpiece, but also hinder the processing efficiency. In order to solve these problems, a new type of porous diamond with high self-sharpening properties was prepared using a thermochemical corrosion method in this study. Our results showed a great improvement in pore volume and specific surface area of the porous diamond compared with ordinary diamond abrasive particles, and the holding force and wettability of vitrified bond to the porous diamond abrasive particles were also improved. Compared with ordinary diamond abrasive tools, porous diamond abrasive tools showed a 29.6% increase in grinding efficiency, a 15.5% decreased in grinding ratio, a 27.5% reduction in workpiece surface roughness, and the scratches on the silicon wafer surface were reduced and refined.
... Additionally, some published studies have shown that NDs could allow charge transfer (CT) processes to organic molecules [8], which might have great importance in the design of the future organic solar cells (OSCs). Compared with other materials NDs would provide great advantages for energy conversion [9][10][11], as they are stable [12], nontoxic [13,14], easy to dispose of, readily available and cheap. ...
In this article 15 DFT functionals were evaluated in order to find a good description of the electronic features and geometries of the nanodiamonds. With this in mind, two sets of molecules were designed, one of them composed by well-known organic molecules and other by diamondoids. The main parameters considered for comparison in this work are the excitation energies, ionization potentials, and the energies of the frontier orbitals. Moreover, absorption distances and binding energies were also considered to assess the quality of the description of the physisorption process. The best overall performance was found on hybrid functionals and more specifically on those with low HF percentage (TPSSH and O3LYP), despite reasonable results with lower computational cost can be obtained with GGA or LDA methods. The use of a correction for the dispersion interaction is mandatory except when a Truhlar functional, LDA or ωB97X functional is used. An augmented triple zeta basis set is recommended, especially for the description of the nanodiamond model, while an augmented double zeta is enough to yield a converged geometry.
... As-received NDs produced by detonation process are labelled as HND due to their numerous C-H bonds and positive zeta potential [16]. NDs that were annealed in air at 450 • C for 30 min to oxidize their structure [17], are labelled as OND. The nominal diameter of both types of NDs is 5 nm. ...
Nanodiamonds (NDs) and graphene oxide (GO) are modern carbon-based nanomaterials with promising features for the inhibition of microorganism growth ability. Here we compare the effects of nanodiamond and graphene oxide in both annealed (oxidized) and reduced (hydrogenated) forms in two types of cultivation media-Luria-Bertani (LB) and Mueller-Hinton (MH) broths. The comparison shows that the number of colony forming unit (CFU) ofEscherichia coliis significantly lowered (45%) by all the nanomaterials in LB medium for at least 24 h against control. On the contrary, a significant long-term inhibition ofE. coligrowth (by 45%) in the MH medium is provided only by hydrogenated NDs terminated with C-H
X
groups. The use of salty agars did not enhance the inhibition effects of nanomaterials used, i.e. disruption of bacterial membrane or differences in ionic concentrations do not play any role in bactericidal effects of nanomaterials used. The specific role of the ND and GO on the enhancement of the oxidative stress of bacteria or possible wrapping bacteria by GO nanosheets, therefore isolating them from both the environment and nutrition was suggested. Analyses by infrared spectroscopy, photoelectron spectroscopy, scanning electron microscopy and dynamic light scattering corroborate these conclusions.
The present study investigates the effect of an oxidized nanocrystalline diamond (O-NCD) coating functionalized with bone morphogenetic protein 7 (BMP-7) on human osteoblast maturation and extracellular matrix mineralization in vitro and on new bone formation in vivo. The chemical structure and the morphology of the NCD coating and the adhesion, thickness and morphology of the superimposed BMP-7 layer have also been assessed. The material analysis proved synthesis of a conformal diamond coating with a fine nanostructured morphology on the Ti6Al4V samples. The homogeneous nanostructured layer of BMP-7 on the NCD coating created by a physisorption method was confirmed by AFM. The osteogenic maturation of hFOB 1.19 cells in vitro was only slightly enhanced by the O-NCD coating alone without any increase in the mineralization of the matrix. Functionalization of the coating with BMP-7 resulted in more pronounced cell osteogenic maturation and increased extracellular matrix mineralization. Similar results were obtained in vivo from micro-CT and histological analyses of rabbit distal femurs with screws implanted for 4 or 12 weeks. While the O-NCD-coated implants alone promoted greater thickness of newly-formed bone in direct contact with the implant surface than the bare material, a further increase was induced by BMP-7. It can be therefore concluded that O-NCD coating functionalized with BMP-7 is a promising surface modification of metallic bone implants in order to improve their osseointegration.
Ordinary diamond presents the disadvantages of poor self-sharpening and concentrated grinding stress when it is used as an abrasive. Moreover, this kind of diamond cannot be well wetted by the vitrified bond, resulting in a lower holding force of the binder to the abrasives (i.e., the diamond is easy to detach from the binder matrix during grinding). These comprehensive factors not only reduce the surface quality of the processed workpiece, but also hinder the processing efficiency. In order to solve these problems, a new type of porous diamond with high self-sharpening properties was prepared using a thermochemical corrosion method in this study. Our results showed a great improvement in pore volume and specific surface area of the porous diamond compared with ordinary diamond abrasive particles, and the holding force and wettability of vitrified bond to the porous diamond abrasive particles were also improved. Compared with ordinary diamond abrasive tools, porous diamond abrasive tools showed a 29.6% increase in grinding efficiency, a 15.5% decreased in grinding ratio, a 27.5% reduction in workpiece surface roughness, and the scratches on the silicon wafer surface were reduced and refined.
Nanodiamonds, commonly described as fragments of diamond, have been theoretically found to have lower HOMO-LUMO energy splitting compared to the bandgap of bulk diamond. This apparent lack of correlation between theory and experiment is caused by the position of the LUMO, which is placed in the surface of the ND. An eventual enlargement of the ND towards a macroscopic size will turn the LUMO into the unoccupied surface states, which are not accounted if the bandgap of a bulk material is measured. Here, the electron structure of the nanodiamonds is evaluated, demonstrating that due their nature they should be described as discrete systems instead of bulk materials. Hence, the word bandgap should be avoided in the case of the nanodiamonds, using HOMO-LUMO gap instead. Additionally, our obtained ionization potentials show a satisfactory degree of correlation with the experiment, while the electron affinities are found to be positive. Although this feature fits the estimation performed from experimental data, it opposes the generally accepted idea of a negative electron affinity for hydrogenated nanodiamonds. The present article clarifies common misunderstandings regarding the electronic nature of the NDs, and provides some guidelines for the correct computation of this systems. Finally, as a helpful tool, an estimation of the content of carbon atoms and its surface to volume ratio is provided starting from the diamond unit cell.
Nanoscale composite of detonation nanodiamond (DND) and polypyrrole (PPy) as a representative of organic light-harvesting polymers is explored for energy generation, using nanodiamond as an inorganic electron acceptor. We present a technology for the composite layer-by-layer synthesis that is suitable for solar cell fabrication. The formation, pronounced material interaction, and photovoltaic properties of DND-PPy composites are characterized down to nanoscale by atomic force microscopy, infrared spectroscopy, Kelvin probe, and electronic transport measurements. The data show that DNDs with different surface terminations (hydrogenated, oxidized, poly-functional) assemble PPy oligomers in different ways. This leads to composites with different optoelectronic properties. Tight material interaction results in significantly enhanced photovoltage and broadband (1–3.5 eV) optical absorption in DND/PPy composites compared to pristine materials. Combination of both oxygen and hydrogen functional groups on the nanodiamond surface appears to be the most favorable for the optoelectronic effects. Theoretical DFT calculations corroborate the experimental data. Test solar cells demonstrate the functionality of the concept.
Plasma chemical surface modification of nanoparticles in gas–liquid type reactors enables a controllable, specific, low-cost, and environmentally friendly alternative to wet chemistry methods or thermal and dry plasma treatments. Here the atmospheric pressure radio-frequency microplasma jet (µ-APPJ) operating with 0.6% O2 in He is used to deliver aqueous oxygen radicals (AOR) to the surface of ∼3 nm hydrogenated detonation nanodiamonds (H-DNDs) suspended in water. The AOR-treated H-DND samples are characterized by FTIR and XPS spectroscopies and by AFM and SEM imaging. The main chemical reaction mechanism is identified as the abstraction of surface hydrogen atoms by O or OH radicals and a consequent attachment of the OH group, thereby increasing concentration of alcohols, carboxyls, and aldehydes on the DND's surface. FTIR spectra reveal also a structural re-arrangement of the surface water on the AOR-treated H-DNDs. Yet zeta-potential of AOR-treated H-DNDs still remains positive (decreases from +45 mV to +30 mV). The chemical modification gives rise to formation of nanoscale chain-like aggregates when AOR-treated H-DNDs are deposited on Si substrate.
Diamond nanoparticles (DNPs) of various types have been recently reported to possess antibacterial properties. Studies have shown a decrease of the colony forming ability on agar plates of the bacteria that had been previously co-incubated with DNPs in the suspension. Before plating, bacteria with DNPs were adequately diluted in order to obtain a suitable number of colony forming units. However, residual DNPs were still present on an agar plate, concentrated on the surface during the plating process; this introduces a potential artifact which might affect colony growth. The effect of DNPs remaining on the surface, alongside growing bacteria, has not been previously investigated. In this work, we present the experiments designed to investigate the effect of DNPs on bacterial survival and on the growth of the bacterial colony on a solid media. We employed Escherichia coli and Bacillus subtilis as models of Gram-negative and Gram-positive bacteria, respectively, and Proteus mirabilis as a model of bacterium exhibiting swarming motility on the surfaces. We analyzed the number, area, and weight of bacterial colonies grown on the agar surface covered with DNPs. We did not observe any bactericidal effect of such applied DNPs. However, in all bacterial species used in this work, we observed the appreciable reduction of colony area, which suggests that DNPs obstruct either bacterial growth or motility. The most obvious effect on colony growth was observed in the case of motile P. mirabilis. We show that DNPs act as the mechanical barrier blocking the lateral colony growth.
Metal materials have been used as implants, due to their excellent mechanical properties and corrosion resistance. However, in order to better bind to living bone they need an interfacial inorganic layer. Biological apatite is a bioactive and biocompatible inorganic material, and the main structural component of human bones. However, it has weak mechanical properties and adhesion to metal implant surfaces. Combination of the good mechanical properties of metals with the bioactive properties of apatite has fostered the application of apatite coatings on metal implants. On the other hand, carbonbased materials (diamond-like carbon, detonational nanodiamond, carbon nanotubes, amorphous carbon, etc.) significantly improve the mechanical properties of AP, increase its adhesion, and prevent metal ion release from metal implants. Our goal was to create a new advanced composite material that is to serve as a coating of metal implants. Stainless steel was used for the electrodeposition of the apatite-nanodiamond coatings in simulated body fluid. The results revealed the formation of dense and homogeneous apatite-nanodiamond composite coatings, with better ductility, hardness, cohesion and adhesion to stainless steel, in comparison to pure apatite coatings. We consider that the nanodiamond-reinforced apatite coatings can be considered as advanced materials for the surface modification of metal implants.
Nanoscale diamond has recently received considerable attention due to the various possible applications such as luminescence imaging, drug delivery, quantum engineering, surface coatings, seeding etc. For most of these fields a suitable surface termination and functionalization of the diamond materials are required. In this feature article we discuss recent achievements in the field of surface modification of nanoscale diamond including the establishment of a homogeneous initial surface termination, the covalent and non-covalent immobilization of different functional moieties as well as the subsequent grafting of larger (bio)molecules onto previously functionalized nanodiamond.
S olid-state nanoparticles hold great promises for biomedical applications, notably thanks to the possibility to combine biological and inorganic materials with the prospect to develop innovative di-agnostic and therapeutic tools. Among them, nanoparticles such as quantum dots, 1,2 gold nanobeads, 3 or silicon beads 4 are used to label a biomolecule with high specificity, to track their fate in cultured cells and in organisms, or even to deliver bioactive molecules or drugs. Organic dyes and fluorophores are nowadays the most widely used fluorescent labels of biomole-cules. However, they photobleach rapidly under continuous illumination, 5 which makes their quantification and long-term follow-up difficult. Interestingly, semicon-ductor nanocrystals, or quantum dots (QDs), have a better stability and a lower photo-bleaching yield than organic dyes. They also offer the possibility of multicolor staining by size tuning. 2 On the other hand, such nanoparticles present major drawbacks, such as a potential cytotoxicity on long-term scale due to the chemical composi-tion of their core 6 or the intermittency of their photoluminescence (photoblinking), which makes an efficient tracking of indi-vidual nanoparticles difficult. 7
The results, resolution and accuracy of Kelvin force microscopy (KFM) on highly conductive (hydrogenated) and highly resistive (oxidized) diamond surfaces are discussed in detail. Electronic properties of the interface between hydrogen and oxygen terminated surface regions are investigated using KFM profiles across in-plane gate transistor structures. Measurements under sub-band gap illumination are interpreted in terms of a surface photovoltage effect and are used to deduce information about surface and interface states.
The Prato reaction is a highly valued reaction for the functionalization of fullerenes and carbon nanotubes. It uses the generation of pyrrolidine rings from azomethine ylides in the formation of a covalent grafting of functional moieties. Here we present the first application of this reaction on thermally annealed nanodiamond as a way for the grafting of a multitude of functional moieties. We used two types of azomethine ylides (aliphatic and pyridine derived) to show the broad applicability of the reaction for the surface modification of nanodiamond. The possibility to attach glycol units or alkyl chains, both with or without reactive terminal groups opens the way to tune the surface properties of such “Prato-functionalized” diamond in a very flexible way.
Electrostatic charging of oxygen-terminated nanocrystalline diamond (NCD) thin films deposited on silicon in sub-100nm thickness and with intentionally high relative sp2 phase ratio (60%) is characterized on a microscopic level. By correlating Kelvin Force Microscopy, Current-Sensing Atomic Force Microscopy, micro-Raman spectroscopy and cross-sectional Scanning Electron Microscopy data we show that the charging is determined by both the surface topography (grains and grain boundaries) and complex sub-surface morphology (arrangement of grains and sp2 phase) on scales below 2×2μm2. These microscopic data and macroscopic I(V) characteristics evidence that sp2 phase dominates over diamond grains in local electrostatic charging of NCD thin films. Moreover, the tip-surface junction quality is identified as the main factor behind large variations (0.1 to 1V) of the overall induced electrostatic charge contrast.
Fourier-transform infrared photoacoustic spectroscopy (FTIR-PAS) is shown to be a useful tool for structural studies of hydrogen and/or oxygen chemisorption on the surface of diamond powders. As compared with the diffuse reflectance method or the KBr pellet method, it has become clear that PAS has an advantage in terms of surface sensitivity. The possibility of quantitative analysis of chemisorbed hydrogen has also been demonstrated.
Detonation diamond is a promising material for biological applications due to its biocompatibility and fluorescence from lattice defects. Here we report on the organic functionalisation method for small detonation diamond agglomerates. After surface homogenisation by reduction and grafting of a silane linker, amino acids have been coupled to the diamond surface and the formation of a small peptide has been achieved. These novel functionalised diamond materials are potentially useful for the synthesis of surface-bound peptides and for the attachment of biologically active building blocks, which could be used in drug delivery and fluorescence marker applications.