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Fully aromatic helicenes are attractive building blocks for the construction of inherently chiral π-conjugated macrocyclic nanocarbons. These hitherto rare molecular architectures are envisaged to exhibit remarkable (chir)optical properties, self-assembly, charge/spin transport, induced ring current or a fascinating Möbius topology. Here the synthesis of helically chiral macrocycles that combine angular dibenzo[5]helicene units as corners and linear

Electron emission plays an important role in diverse applications, from cold cathodes to chemical processes (solvated electrons, water purification), energy generation (thermionic or dye-sensitized solar cells), and even cancer treatment. Here we show that by surface treatment using electrochemically grown polypyrrole the secondary-electron emission and photoelectron emission from boron-doped diamond is enhanced even above the intensity of electron emission from the hydrogen-terminated surface with negative electron affinity. This enhancement is stable in air for at least one month and it persists also in vacuum after thermal annealing. Scanning electron microscopy, Kelvin probe force microscopy, total photoelectron yield spectroscopy as well as surface mapping by Auger and secondary ion mass spectroscopies are used to characterize and correlate the surface electronic and chemical properties. A model of the electron emission enhancement is provided.

ZnO biointerfaces with serum albumin have attracted noticeable attention due to the increasing interest in developing ZnO-based materials for biomedical applications. ZnO surface morphology and chemistry are expected to play a critical role on the structural, optical, and electronic properties of albumin-ZnO complexes. Yet there are still large gaps in the understanding of these biological interfaces. Herein we comprehensively elucidate the interactions at such interfaces by using atomic force microscopy and nanoshaving experiments to determine roughness, thickness, and adhesion properties of BSA layers adsorbed on the most typical polar and non-polar ZnO single-crystal facets. These experiments are corroborated by force field (FF) and density-functional tight-binding (DFTB) calculations on ZnO-BSA interfaces. We show that BSA adsorbs on all the studied ZnO surfaces while interactions of BSA with ZnO are found to be considerably affected by the atomic surface structure of ZnO. BSA layers on the (0001‾) surface have the highest roughness and thickness, hinting at a specific upright BSA arrangement. BSA layers on (101‾0) surface have the strongest binding, which is well correlated with DFTB simulations showing atomic rearrangement and bonding between specific amino acids (AAs) and ZnO. Besides the structural properties, the ZnO interaction with these AAs also controls the charge transfer and HOMO-LUMO energy positions in the BSA-ZnO complexes. This ZnO facet-specific protein binding and related structural and electronic effects can be useful for improving the design and functionality of ZnO-based materials and devices.

Boron derivatives have great potential in cancer diagnostics and treatment. Borocaptates are used in boron neutron capture therapy and potentially in proton boron fusion therapy. This work examines modulation effects of two borocaptate compounds on radiation-induced DNA damage. Aqueous solutions of pBR322 plasmid containing increasing concentrations of borocaptates were irradiated with 60Co gamma rays or 30 MeV protons. Induction of single and double DNA strand breaks was investigated using agarose gel electrophoresis. In this model system, representing DNA without the intervention of cellular repair mechanisms, the boron derivatives acted as antioxidants. Clinically relevant boron concentrations of 40 ppm reduced the DNA single strand breakage seven-fold. Possible mechanisms of the observed effect are discussed.

Nanocrystalline diamond (NCD) layers functionalized with amine-containing functional groups have generated considerable interest as biocompatible substrates for attachment of biomolecules and cells with a view to biosensor and tissue engineering applications. Here we prepare nanoporous diamond layers with the surfaces modified by hydrogen plasma, oxygen plasma, and conformal 7 nm amine-containing plasma polymer (PP). Immobilization of bovine serum albumin (BSA) molecules is characterized on such surfaces. Grazing angle reflectance infrared spectroscopy as well as X-ray photoelectron spectroscopy show that concentration of amine-containing bonds after BSA exposure depends on the type of NCD surface modification. AFM measurements reveal that BSA proteins are physisorbed on H- and O-terminated diamond surfaces in different thicknesses and morphology. When the diamond layers are coated with the amine-containing PP, BSA molecules assume similar thickness and morphology, and their adhesion is significantly increased on both types of the diamond surfaces.

A compromised detection of radiation-induced plasmid DNA fragments results in underestimation of calculated damage yields. Electrophoretic methods are easy and cheap, but they can only detect a part of the fragments, neglecting the shortest ones. These can be detected with atomic force microscopy, but at the expense of time and price. Both methods were used to investigate their capabilities to detect the DNA fragments induced by high-energetic heavy ions. The results were taken into account in calculations of radiation-induced yields of single and double strand breaks. It was estimated that the double strand break yield is twice as high when the fragments are at least partially detected with the agarose electrophoresis, compared to when they were completely omitted. Further increase by 13% was observed when the measured fragments were corrected for the fraction of the shortest fragments up to 300 base pairs, as detected with the atomic force microscopy. The effect of fragment detection on the single strand break yield was diminished.

Recent interest in industrial and medical usage of carbon nanomaterials arises the need for approved testing protocols for characterizing their interaction with living systems. Nanocrystalline diamond (NCD) films were chosen as a promising material for such investigation due to their unique mechanical properties, chemical stability and biocompatibility. In this study, we examined the anti-adhesive properties of differently terminated NCD films deposited by plasma-enhanced CVD on glass or silicon against Escherichia coli bacterium. We focused on the influence of cultivation medium in this process and compared bacterial adhesion to H-, O- and F-terminated NCD films in complex Luria-Bertani (LB) and mineral (M9) cultivation media that substantially differ in the content of organic molecules and thus in the potential of conditioning film formation. We found the properties of NCD films to be independent of the base substrate, as the amount of biofilm was comparable for both NCD films deposited on glass and on silicon. The anti-adhesive effect was observed only in the mineral medium where hydrogen and fluorine terminated NCD films reduced bacterial adhesion by ca. 50%. In complex medium we did not observe the reduction of bacterial adhesion. These differences are attributed to the passivation of the H- or F-terminated NCD films by organic molecules adsorbed from the complex medium. For O-terminated NCD films, no anti-adhesive effect was observed, regardless of the cultivation medium. Our results show that the growth of Escherichia coli in mineral cultivation medium can be affected by the diamond atomic termination.

Samples of a palladium catalyst for direct formic acid fuel cell (DFAFC) applications were prepared on the Elat ® carbon cloth by magnetron sputtering. The quantity of Pd was equal to 3.6, 120 and 720 μg/cm 2 . The samples were tested in a fuel cell for electro-oxidation of formic acid, and were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The XPS measurements revealed a high contribution of PdC x phase formed at the Pd/Elat ® surface interface, with carbon concentration in PdC x from x = 9.9–14.6 at.%, resulting from the C substrate and CO residual gases. Oxygen groups, e.g. hydroxyl (–OH), carbonyl (C O) and carboxyl (COOH), resulted from the synthesis conditions due to the presence of residual gases, electro-oxidation during the reaction and oxidation in the atmosphere. Because of the formation of CO and CO 2 on the catalysts during the reaction, or because of poisoning by impurities containing the –CH 3 group, together with the risk of Pd losses due to dissolution in formic acid, there was a negative effect of catalyst degradation on the active area surface. The effect of different loadings of Pd layers led to increasing catalyst efficiency. Current–voltage curves showed that different amounts of catalyst did not increase the DFAFC power to a great extent. One reason for this was the catalyst structure formed on the carbon cloth. AFM and SEM measurements showed a layer-by-layer growth with no significant variations in morphology. The results for electric power recalculated for the Pd loading per 1 mg of catalyst layers in comparison to carbon substrates decorated by Pd nanoparticles showed that there is potential for applying anodes for formic acid fuel cells prepared by magnetron sputtering.

Cell fate modulation by adapting the surface of a biocompatible material is nowadays a challenge in implantology, tissue engineering as well as in construction of biosensors. Nanocrystalline diamond (NCD) thin films are considered promising in these fields due to their extraordinary physical and chemical properties and diverse ways in which they can be modified structurally and chemically. The initial cell distribution, the rate of cell adhesion, distance of cell migration and also the cell proliferation are influenced by the NCD surface termination. Here, we use real-time live-cell imaging to investigate the above-mentioned processes on oxidized NCD (NCD-O) and hydrogenated NCD (NCD-H) to elucidate cell preference to the NCD-O especially on surfaces with microscopic surface termination patterns. Cells adhere more slowly and migrate farther on NCD-H than on NCD-O. Cells seeded with a fetal bovine serum (FBS) supplement in the medium move across the surface prior to adhesion. In the absence of FBS, the cells adhere immediately, but still exhibit different migration and proliferation on NCD-O/H regions. We discuss the impact of these effects on the formation of cell arrays on micropatterned NCD. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1469-1478, 2017.

Study of friction and energy dissipation always relied on direct observations. Actual theories provide limited prediction on the frictional and dissipative properties if only the material chemistry and geometry are known. We here develop a framework to study intrinsic friction and energy dissipation based on the only knowledge of the normal modes of the system at equilibrium. We derive an approximated expression for the first anharmonic term in the potential energy expansion which does not require the computation of the third-order force constants. Moreover, we show how to characterize the frequency content of observed physical quantities and individuate the dissipative processes active during experimental measurements. As a case study, we consider the relative sliding motion of atomic layers in molybdenum disulfide dry lubricant, and we discuss how to extract information on the energetics of sliding from atomic force microscopy signals. The presented framework switches the investigation paradigm on friction and energy dissipation from dynamic to static studies, paving avenues to explore for the design of alternative anisotropic tribological and thermal materials.

Two profoundly different carbon allotropes - nanocrystalline diamond and graphene - are of considerable interest from the viewpoint of a wide range of biomedical applications including implant coating, drug and gene delivery, cancer therapy, and biosensing. Osteoblast adhesion and proliferation on nanocrystalline diamond and graphene are compared under various conditions such as differences in wettability, topography, and the presence or absence of protein interlayers between cells and the substrate. The materials are characterized in detail by means of scanning electron microscopy, atomic force microscopy, photoelectron spectroscopy, Raman spectroscopy, and contact angle measurements. In vitro experiments have revealed a significantly higher degree of cell proliferation on graphene than on nanocrystalline diamond and a tissue culture polystyrene control material. Proliferation is promoted, in particular, by hydrophobic graphene with a large number of nanoscale wrinkles independent of the presence of a protein interlayer, i.e., substrate fouling is not a problematic issue in this respect. Nanowrinkled hydrophobic graphene, thus, exhibits superior characteristics for those biomedical applications where high cell proliferation is required under differing conditions.

Diamond is considered as a promising tissue equivalent material in radiation therapies as well as for bio-electronic sensors due to its unique set of properties. These features are combined in this work where effects of gamma irradiation ( 60 Co, up to 300 Gy) on function and stability of microscopic (60 × 20 μm 2 ) hydrogen-terminated diamond (H-diamond) solution-gated field effect transistors (SG-FETs) are studied. The H-diamond SG-FETs were prepared using 300 nm thin diamond films deposited on glass from methane and hydrogen gas mixture by microwave plasma. Prior to gamma irradiation they were interfaced to proteins (fetal bovine serum) and cells (human sarcoma osteogenic cell line — SAOS2) in cell growth medium. Blank H-diamond SG-FETs did not degrade after the irradiation. With adsorbed proteins and cells they showed specific changes in gate current characteristics (about 100% increase) after the irradiation. These current changes are attributed to modified protein layer and cell morphology on the diamond surface. The presented results establish a first step towards real-time electronic monitoring of cell growth during the irradiation by therapeutically relevant doses.

The properties of nanocrystalline diamond (NCD) films offer great potential for the creation of various sensing and photonic devices. A great challenge in order to materialize such applications lies in achieving the micrometrically resolved functionalization of NCD surfaces. In the present work, we introduce a facile approach to meet this challenge employing the novel strain-promoted alkyne–azide cycloaddition “click” chemistry reaction, a catalyst-free ligation protocol compatible with biomolecules. The ability to achieve well-resolved multicomponent patterns with high reproducibility is demonstrated, paving the way for the fabrication of novel devices based on micropatterned NCD films.

The study of the chemical composition of buried interfaces by X-ray photoelectron spectroscopy (XPS) is limited by the inelastic mean free path of emitted photoelectrons (PE). Soft X-ray sources (AlKα) are generally suitable for careful probing of surfaces or very thin films. Here we applied gas cluster ion beam sputtering in combination with in-situ XPS (GCIB-XPS) to analyze buried GaP/Si(0 0 1) heterointerfaces. The GCIB method was used to dig a crater into the 20 nm thick GaP(0 0 1) film. We found optimal parameters for GCIB sputtering and achieved interface layers without severe damage. Destructive effects, i.e. broadening of core level peaks, could not be completely avoided, however, and the formation of metallic Ga on the GaP surface was observed. PE spectra of the sputtered heterostructures were compared with corresponding reference spectra of sputtered bulk crystals. Interface contributions to the intensity of phosphorus and sillicon core level peaks were revealed: interface components are shifted to high binding energies of P 2p Si 2p core levels. Similar results were obtained on 4 nm thick GaP/Si(0 0 1) by XPS. Finally, a top-to-bottom concept for buried semiconductor interfaces studies by GCIB-XPS is demonstrated.

The work presented here aimed to synthesize the non-conducting form of PANI nanofibrils and to study their properties, which are determined by their chemical structure and morphology. Non-conducting PANI nanofibrils were synthesized by an alkali-based treatment process. Raman measurements revealed that synthesized PANI nanofibrils consist mainly of benzenoid units with a small number of quinoid units. Calculations based on Raman spectra show that ratio of benzenoid to quinoid units is 3:1. This ratio is 3 times higher than the characteristic/typical value for synthesized non-conducting PANI, as reported in the literature. Moreover, the photoluminescence of these non-conducting PANI nanofibrils (measured with excitation of 442 nm) possesses two maxima, with wavelengths of 550 nm and 1110 nm. These wavelengths correspond to photon energies of 2.25 eV and 1.12 eV, which resemble very long Stokes shifts of 108 nm and 658 nm, respectively. This finding has not been presented previously. However, when the excitation is performed with a 785 nm red laser, the emission spectra of non-conducting PANI nanofibrils exhibit numerous sharp emission peaks. We attribute these transitions to the chemical structure of the synthesized polymer chains and to its nanofibril morphology.

In this study, we examined dose-rate effects on strand break formation in plasmid DNA induced by pulsed extreme ultraviolet (XUV) radiation. Dose delivered to the target molecule was controlled by attenuating the incident photon flux using aluminum filters as well as by changing the DNA/buffer-salt ratio in the irradiated sample. Irradiated samples were examined using agarose gel electrophoresis. Yields of single- and double-strand breaks (SSBs and DSBs) were determined as a function of the incident photon fluence. In addition, electrophoresis also revealed DNA cross-linking. Damaged DNA was inspected by means of atomic force microscopy (AFM). Both SSB and DSB yields decreased with dose rate increase. Quantum yields of SSBs at the highest photon fluence were comparable to yields of DSBs found after synchrotron irradiation. The average SSB/DSB ratio decreased only slightly at elevated dose rates. In conclusion, complex and/or clustered damages other than cross-links do not appear to be induced under the radiation conditions applied in this study.

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.

Titanium, the gold standard for dental implant materials, is distinguished by its exceptional biocompatibility; however, from a long-term perspective, titanium still lacks sufficient loading strength. Commercially pure titanium with grain size 30 μm was processed by equal channel angular pressing, and two novel mechanically improved types of titanium material with grain size 4.6 and ≤1 µm were obtained. The surfaces of these ultra-fine grained titanium samples were further mechanically treated by grinding and polishing, and their surfaces were characterized by atomic force microscopy and contact angle measurement. Osteoblast-like cells and human mesenchymal stem cells were used to evaluate the cytocompatibility of these titanium samples. The cell metabolic activity, cell number, cell area, morphology, and cell adhesion quality during the early stage (2 h) and prolonged cultivation (48 h) were determined. Both cell types displayed increased initial attachment to all tested titanium materials in comparison to reference tissue culture plastic. Importantly, results revealed that the novel titanium materials with improved strength were equivalent to the original commercially pure titanium, thus confirming their suitability for osteoblast and mesenchymal stem cell growth and proliferation. The present study proved the cytocompatibility of the novel forms of titanium with superior mechanical properties and revealed their potential for manufacturing of long-term dental implants.

Possible dose-rate effects in a plasmid DNA exposed to pulsed extreme ultraviolet (XUV) and soft x-ray (SXR) water window radiation from two different table-top plasma-based sources was studied. Dose delivered to the target molecule was controlled by attenuating the incident photon flux with aluminum thin foils as well as varying the DNA/buffer-salt ratio in the irradiated sample. Irradiated samples were analyzed using the agarose gel electrophoresis. Some additional bands were identified in gel electrophoretograms as results of a DNA cross-linking. They were inspected by atomic force microscopy (AFM). Yields of single- and double-strand breaks (Gy-1 Da-1) were determined as a function of incident dose rate. Both yields decreased with a dose rate increasing. The ratio of single- and double-strand breaks exhibited only a slight increase at elevated dose rates. In conclusion, complex and/or clustered damages do not seem to be initiated under these irradiation conditions.

Tailorable surface termination of nanocrystalline diamond (NCD) and diamond-like carbon (DLC) films significantly contribute to their wide potential applications in biomedicine which require defined and stable surface towards aging. Here, we present a comparative study on the surface termination stability of NCD and DLC films in terms of XPS and water contact angle (WCA) measurements. The samples were plasma-treated with hydrogen, oxygen or nitrogen containing functional groups employing low temperature radio frequency (RF) or high temperature microwave (MW) plasma. The samples were exposed to air up to 30 days, during which the termination stability was analyzed by XPS, WCA, AFM, Raman spectroscopy and SEM measurements. It was shown that NCD films were more efficiently hydrogenated in the high temperature MW plasma than in RF plasma, and also the surface stability was better. However, the MW plasma deteriorated the surface of the DLC film. In RF plasma treatment, a contrast between WCA and XPS data was observed. Surprisingly, while the XPS measurements showed relatively stable surface termination for all cases (H-, O- and NH2-terminated surfaces), the WCA values for O- and NH2-treated samples increased by ~200 ÷ 300%. Generally, the NCD film showed more stable surface termination than DLC. The possible reasons of the different behavior of WCA and XPS results, as well as complex characterization of the surface properties of H-, O- and NH2-terminated NCD and DLC film regarding to the aging and surface termination stability are discussed in the article.

Diamond exhibits good biocompatibility and a large electrochemical potential window, and thus, it is particularly suitable for bio-functionalization and bio-sensing. Modification of the diamond surface can be achieved through mussel-inspired surface chemistry based on polydopamine (PDA) while maintaining the intrinsic properties of the surface. We present a comparative study on the polymerization/deposition of PDA from an aqueous solution of dopamine on hydrogen- (H) and oxygen- (O) terminated nanocrystalline diamond films (NCD). The dopamine polymerization/deposition was performed under mild conditions, which resulted in a confluent PDA layer. A detailed investigation of the growth kinetics of the PDA film on H- and O-terminated NCD substrates was performed using spectroscopic ellipsometry. The chemical composition, the functional group distribution, the surface topography and the wetting properties of the adherent PDA films were evaluated using X-ray photoelectron spectroscopy, atomic force microscopy and water contact angle goniometry, respectively. According to the results, a PDA layer can be used as a platform for future bio-functionalization and/or optical bio-sensing applications.

Cell fate modulation by adapting the surface of a biocompatible material is nowadays a challenge in implantology, tissue engineering as well as in construction of biosensors. Nanocrystalline diamond (NCD) thin films are considered promising in these fields due to their extraordinary physical and chemical properties and diverse ways in which they can be modified structurally and chemically. The initial cell distribution, the rate of cell adhesion, distance of cell migration and also the cell proliferation are influenced by the NCD surface termination. Here, we use real-time live-cell imaging to investigate the above-mentioned processes on oxidized NCD (NCD-O) and hydrogenated NCD (NCD-H) to elucidate cell preference to the NCD-O especially on surfaces with microscopic surface termination patterns. Cells adhere more slowly and migrate farther on NCD-H than on NCD-O. Cells seeded with a fetal bovine serum (FBS) supplement in the medium move across the surface prior to adhesion. In the absence of FBS, the cells adhere immediately, but still exhibit different migration and proliferation on NCD-O/H regions. We discuss the impact of these effects on the formation of cell arrays on micropatterned NCD. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1469-1478, 2017.

We employ nanocrystalline diamond (NCD) thin films with average grain sizes of 250 and 80 nm to resolve influence of grain boundaries and sp 2 phase on protein adsorption and electronic function of solution-gated field-effect transistors (SGFET). Microscopic (20 μm × 60 μm) SGFETs are fabricated without gate oxides based on hydrogen-terminated NCD films on glass substrates. We show that NCD with grain sizes down to 80 nm and film thickness of 100 nm is fully operational as SGFET. We find that inherent hysteresis of SGFET transfer characteristics, their reaction time, their negative shift after protein adsorption and cell culturing process, low gate leakage currents and no influence of UV sterilization or rinsing are all independent of the NCD grain size. Thus we propose a microscopic model where the function of NCD SGFET is determined by the H-terminated surface of diamond nanocrystals and its interaction with proteins, not by grain boundaries or sp 2 phase in general.

The nanocrystalline diamond (NCD) layers were grown by the large area (linear plasma) MWCVD on polished silicon substrates with and without intermediate mirror-like metallic coatings. The optical reflectance and Raman spectroscopy in the ultraviolet, visible and near infrared region (UV–VIS–NIR) reveals the thickness and the optical quality of NCD layers. The modified grazing angle reflectance (GAR) spectroscopy is applied in the mid infrared region 800–4000/cm to detect the molecular vibrations (functional groups) at the functionalized NCD surface. The optical absorbance of functionalized NCD surface is evaluated from p-polarized reflectance spectra measured at Brewster angle of incidence (BAR) to eliminate the interference fringes. We report a significant enhancement of sensitivity of BAR using NCD growth on metal mirrors.

Compromised detection of short DNA fragments can result in underestimation of radiation-induced clustered DNA damage. The fragments can be detected with atomic force microscopy (AFM), followed by image analysis to compute the length of plasmid molecules. Plasmid molecules imaged with AFM are represented by open or closed curves, possibly with crossings. For the analysis of such objects, a dedicated algorithm was developed, and its usability was demonstrated on the AFM images of plasmid pBR322 irradiated with 60Co gamma rays. The analysis of the set of the acquired AFM images revealed the presence of DNA fragments with lengths shorter than 300 base pairs that would have been neglected by a conventional detection method.

Several technological approaches of applying photoresistive polymer for patterning the diamond seeding layer while minimizing damage of substrate surface is reported. Reactive ion etching (i.e., dry process) and wet photolithographical processing using two polymer layers are compared and combined as treatment techniques. Subsequently, diamond structures are deposited by microwave plasma enhanced chemical vapor deposition from a gas mixture of methane diluted in hydrogen. The highest efficiency for selected-area deposition, with the parasitic density as low as the technological limit of 105 cm−2, was achieved by combining the two treatment techniques. Technological advantages and limitation of dry and wet treatment process are pointed out.

We investigate the role of fetal bovine serum (FBS) proteins in the assembly of osteoblastic cells (SAOS-2) in McCoy's 5A medium on synthetic monocrystalline and nanocrystalline diamonds having H- and O-terminated array patterns. We characterize i) adhesion of proteins and cells to diamond by shaking experiments (1000 rpm), fluorescence, and atomic force microscopy, ii) distribution of FBS proteins by micro-Raman spectroscopy, and iii) influence of pre-adsorbed specific FBS proteins (albumin, fibronectin, vitronectin) on the cell assembly. There is 40% lower adhesion of cells on H-terminated diamond with adsorbed FBS compared to this surface without FBS as well as to O-terminated surfaces. Spatially resolved Raman spectroscopy of C―H stretching bands around 2900 cm− 1 showed uniform coverage of H/O-diamond by the albumin in more than 50 nm thick FBS layers. The other FBS proteins were not detectable by Raman. Pre-adsorption of the specific proteins prior to cell plating indicated that the cell preference to O-terminated diamond is controlled by the fibronectin rather than by the albumin. We discuss the data with a view to the cell preferential assembly on H/O-diamond micro-arrays.

We investigate adhesion of fetal bovine serum (FBS) on diamond surfaces which have alternating H/O-terminated surface patterns of 30 μm width prepared by hydrogen and oxygen plasma. The samples are immersed into 15% FBS in McCoy's 5A supporting medium and characterized by in situ atomic force microscopy (AFM) during 6 days of adsorption. Within the first day, 2-4 nm primary layer is formed on both H-/O-terminated surfaces. After 6 days, we observe 17 ± 5 nm FBS layer on O-terminated surface and 35 ± 5 nm layer on H-terminated surface. Adhesion of the primary and secondary layer is weaker on H-terminated surface. We present a model of FBS protein layers on H-/O-terminated diamond and we discuss implications for a preferential cell growth on O-terminated diamond. We also show that the preferential cell growth is not affected by the long-term FBS pre-adsorption.

article i nfo We investigate adsorption of fetal bovine serum (FBS), a crucial component for cell growth, on intrinsic CVD mono-crystalline diamond with hydrogen and oxygen surface terminations. The surface terminations are prepared by oxygen and hydrogen plasma process. The FBS adsorption is done by immersing diamond into McCoy's 5A medium supplemented with 15% FBS for 10 s-24 h. After rinsing the samples are characterized in the McCoy's medium and for comparison also in air by atomic force microscopy (AFM). By optimized measurements of AFM topography in oscillating regime and by using advanced AFM regimes such as phase imaging, nanoshaving, and force spectroscopy we characterize FBS thickness, adhesion, conformation and selectivity on the H/O-diamond surfaces. We find that FBS is adsorbed in about the same monolayer thickness (2-4 nm) on both H/O-diamond surfaces, yet the protein conformation is different. We present a schematic model.

We show correlation of microscopic surface quality and morphology of nanocrystalline diamond films as a function of deposition temperature and post-growth acid treatment detected by atomic force microscopy in phase detection regime, X-ray photoelectron spectroscopy, X-ray induced Auger electron spectroscopy, Scanning Electron Microscopy, Raman spectroscopy, and the electrical conductivity of H-terminated diamond surfaces. The correlation reflects the decrease in sp 2 amount and enhanced surface conductivity of the diamond surface after the chemical treatment. These results indicate that the AFM phase can detect clearly and microscopically carbon sp 2 phase on facets and grain boundaries of nanocrystalline diamond films.

We report on the fabrication and practical use of high-quality optical elements based on Au mirrors coated with diamond layers with flat, nanocolumnar, and nanoporous morphologies. Diamond layers (100 nm thickness) are grown at low temperatures (about 300 °C) from a methane, carbon dioxide, and hydrogen gas mixture by a pulsed microwave plasma system with linear antennas. Using grazing angle reflectance (GAR) Fourier transform infrared spectroscopy with p-polarized light, we compare the IR spectra of fetal bovine serum proteins adsorbed on diamond layers with oxidized (hydrophilic) surfaces. We show that the nanoporous diamond layers provide IR spectra with a signal gain of about 600% and a significantly improved sensitivity limit. This is attributed to its enhanced internal surface area. The improved sensitivity enabled us to distinguish weak infrared absorption peaks of

International audience; Linear antenna microwave chemical vapor deposition process was used to homogeneously coat a 7 cm long silicon prism by 85 nm thin nanocrystalline diamond (NCD) layer. To show the advantages of the NCD-coated prism for attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) of nanoparticles, we apply diamond nanoparticles (DNPs) of 5 nm nominal size with various surface modifications by a drop-casting of their methanol dispersions. ATR-FTIR spectra of as-received, air-annealed, plasma-oxidized, and plasma-hydrogenated DNPs were measured in the 4000–1500 cm$^{−1}$ spectral range. The spectra show high spectral resolution, high sensitivity to specific DNP surface moieties, and repeatability. The NCD coating provides mechanical protection against scratching and chemical stability of the surface. Moreover, unlike on bare Si surface, NCD hydrophilic properties enable optically homogeneous coverage by DNPs with some aggregation on submicron scale as evidenced by scanning electron microscopy and atomic force microscopy. Compared to transmission FTIR regime with KBr pellets, direct and uniform deposition of DNPs on NCD-ATR prism significantly simplifies and speeds up the analysis (from days to minutes). We discuss prospects for in situ monitoring of surface modifications and molecular grafting.

Atomic force microscopy (AFM) is a frequently used method applicable also to biological studies due to its capability of measuring in native environment. Sharp Si, Si3N4 or C (carbon nanotubes, diamond, diamond coated) cantilevers repeatedly touching a sample are used in this method as sensitive probes. It is possible to control the interaction between the tip and the sample in order to make less invasive measurements or, conversely, to modify the sample. However, AFM images often contain features which are not present on the sample in reality, but are a direct result of the measurements itself. Such structures or features are denoted as artifacts. The artifacts arise from various reasons. Some of them can be avoided during measurements, other ones are inherent. The artifacts shown in this chapter are divided into several categories based on the part of AFM which is responsible for them. Examples of many artifacts are presented and their reasons are explained. This chapter will be helpful for AFM users who observe strange effects, presumably related to the AFM technique, but do not know their reason. This chapter can also answer questions about the validity of imaged features as well as their accuracy.

Understanding the interaction between the biological environment (tissues, cells, proteins, electrolytes, etc.) and a solid surface is crucial for biomedical applications such as bio-sensors, bio-electronics, tissue engineering and the optimization of implant materials. Cells, the cornerstones of living tissue, perceive their surroundings and subsequently modify it by producing extracellular matrix (ECM), which serves as a basis to simplify their adhesion, spreading and differentiation (Shakenraad & Busscher, 1989). This process is considerably complex, flexible and strongly depends on the cell cultivation conditions including the type of the substrate. Surface roughness of the substrate plays an important role (Babchenko et al., 2009; Kalbacova et al., 2009; Kromka et al., 2009; Zhao et al., 2006), other influential factors include both the porosity (Tanaka et al., 2007) and the wettability of the substrate, the latter influencing protein conformation (Browne et al., 2004; Rezek, Ukraintsev, Michalikova, Kromka, Zemek & Kalbacova, 2009) as well as the adsorption and viability of cells (Grausova et al., 2009; Kalbacova, Kalbac, Dunsch, Kromka, Vanecek, Rezek, Hempel & Kmoch, 2007). Materials which are commonly employed as substrates for in vitro testing are polystyrene and glass. In this context, diamond as a technological material can provide a relatively unique combination of excellent semiconducting, mechanical, chemical as well as biological properties (Nebel et al., 2007). Diamond also meets the basic requirements for large-scale industrial application, most notably, it can be prepared synthetically. Diamond can be synthesized either as a bulk material under high-pressure and high-temperature conditions, or in the form of thin films by chemical vapor deposition of methane and hydrogen on various substrates including glass and metal (Kromka et al., 2008; Potocky et al., 2007). Moreover, the application of selective nucleation makes it possible to directly grow conductive diamond microstructures, which operate e.g. as transistors or pH sensors (Kozak et al., 2010). Nowadays, it is possible to deposit diamond even on large areas (600 cm2 or more) using linear antennas (Kromka et al., 2011; Tsugawa et al., 2010). The excellent compatibility of diamond with biological materials and environment (Bajaj et al., 2007; Grausova et al., 2009; Diamond as Functional Material for Bioelectronics and Biotechnology

Cell migration plays an important role in many biological systems. A relatively simple stochastic model is developed and used to describe cell behavior on chemically patterned substrates. The model is based on three parameters: the speed of cell movement (own and external), the probability of cell adhesion, and the probability of cell division on the substrate. The model is calibrated and validated by experimental data obtained on hydrogen- and oxygen-terminated patterns on diamond. Thereby, the simulations reveal that: (1) the difference in the cell movement speed on these surfaces (about 1.5×) is the key factor behind the formation of cell arrays on the patterns, (2) this difference is provided by the presence of fetal bovine serum (validated by experiments), and (3) the directional cell flow promotes the array formation. The model also predicts that the array formation requires mean distance of cell travel at least 10% of intended stripe width. The model is generally applicable for biosensors using diverse cells, materials, and structures.