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TiO2 has been reported to have considerable capacity through appropriate surface modification. Previous studies of TiO2-based supercapacitors mainly focused on anodized TiO2 nanotubes and TiO2 powder, even though the capacitance still lags behind that of carbon-base materials. In this work, a three-dimensional porous TiO2/Ti (PTT) network was constructed by anodic oxidation and its capacitance was boosted by subsequent aluminum-reduction process. Activated Ti3+ was proved to be being successfully introduced into the surface of pristine PTT, resulting in the prominent enhancement of supercapacitive performance. An areal capacitance of 81.75 mF cm−2 was achieved from Al-reduced PTT (Al-PTT) at 500 °C in 1 M H2SO4 electrolyte, which was among the highest value of pure TiO2-based electrodes. Good electrochemical stability was also confirmed by the 3.12% loss of the highest capacity after 5000 CV cycles. More importantly, the activated Ti3+/Ti4+ redox couple in modified TiO2 is solidly confirmed by being directly observed in CV curves. The capacitive mechanism of the redox reaction is also studied by electrochemical tests. The construction of a 3D porous network structure and efficient Ti3+ introduction provide an effective method to boost the supercapacitive performance of TiO2-based materials for energy storage applications.

Crystalline organic semiconducting materials are much in demand for multiple electronic and optoelectronic device applications. Here, solution grown ultrathin rhombic crystals of a trimethine carbocyanine anionic dye are used to establish relationships between structural and optical properties. The dye crystallized in the monoclinic space group P21/c featuring alternating layers of molecules in two different herringbone type patterns, with perchlorate counterions located mostly within one of the two layers. Micro transmittance spectroscopy revealed a broadened spectrum compared to those obtained in solution and in an amorphous thin film. Using polarized light, transmission spectroscopy revealed strong low-energy and weak high-energy bands polarized along the crystallographic b- and c-axis, respectively. Using the extended dipole approximation, significant exciton couplings are predicted between neighboring molecules in the crystal, of the order of the intrinsic monomer reorganization energies associated with nuclear relaxation after excitation, depicting a complex spectral scenario. The exciton coupling pattern explains the relative energies of the b- and c-polarized components but the observed intensities are opposite to expectations based on chromophore alignment within the crystal.

Five effects of correction of the asymptotic potential error in density functionals are identified that significantly improve calculated properties of molecular excited states involving charge-transfer character. Newly developed materials-science computational methods are used to demonstrate how these effects manifest in materials spectroscopy. Connection is made considering chlorophyll-a as a paradigm for molecular spectroscopy, 22 iconic materials as paradigms for 3D materials spectroscopy, and the VN- defect in hexagonal boron nitride as an example of the spectroscopy of defects in 2D materials pertaining to nanophotonics. Defects can equally be thought of as being "molecular" and "materials" in nature and hence bridge the realms of molecular and materials spectroscopies. It is concluded that the density functional HSE06, currently considered as the standard for accurate calculations of materials spectroscopy, should be replaced, in most instances, by the computationally similar but asymptotically corrected CAM-B3LYP functional, with some specific functionals for materials use only providing further improvements.

International audience; Drug loaded hydrogels have proven to be versatile controlled-release systems. We report here on heat active hydrogel formation by mixing graphene oxide (GO) or carboxyl enriched reduced graphene oxide (rGO-COOH) with metformin hydrochloride, an insulin sensitizer drug currently used as the first line therapy to treat patients with type 2 diabetes. The driving forces of the gelation process between the graphene-based nanomaterial and metformin are hydrogen bonding and electrostatic interactions, weakened at elevated temperature. Using the excellent photothermal properties of the graphene matrixes, we demonstrate that these supramolecular drug reservoirs can be photothermally activated for transdermal metformin delivery. A sustained delivery of metformin was achieved using a laser power of 1 W cm−2. In vitro assessment of the key target Glucose-6 Phosphatase (G6P) gene expression using a human hepatocyte model confirmed that metformin activity was unaffected by photothermal activation. In vivo, metformin was detected in mice plasma at 1 h post-activation of the metformin loaded rGO-COOH gel.

Electrophoretic deposition (EPD) of reduced graphene oxide nanosheets (rGO) offers several advantages over other surface coating approaches, including process simplicity, uniformity of the deposited films, and good control of the film thickness. The EPD conditions might also be of interest for the reduction of diazonium salts, which upon the release of N2 molecules and generation of radicals, can form covalent bonds with the sp2 hybridized carbon lattice atoms of rGO films. In this work, we report on the coating of gold electrodes in one step with rGO/polyethylenimine (PEI) thin films and their simultaneous modification using different phenyl (Ph) diazonium salt precursors bearing various functionalities such as −B(OH)2, −COOH, and −C≡CH. We show further the interest of such interfaces for designing highly sensitive sensing platforms. Azide-terminated lysozyme aptamers were clicked onto the rGO/PEI/Ph-alkynyl matrix and used for the sensing of lysozyme levels in patients suffering from inflammatory bowel ...

Lysozyme is an enzyme found in biological fluids, which is upregulated in leukemia, renal diseases as well as in a number of inflammatory gastrointestinal diseases. We present here the development of a novel lysozyme sensing concept based on the use of Micrococcus lysodeikticus whole cells adsorbed on graphene oxide (GO)-coated Surface Plasmon Resonance (SPR) interfaces. M. lysodeikticus is a typical enzymatic substrate for lysozyme. Unlike previously reported sensors which are based on the detection of lysozyme through bioaffinity interactions, the bioactivity of lysozyme will be used here for sensing purposes. Upon exposure to lysozyme containing serum, the integrity of the bacterial cell wall is affected and the cells detach from the GO based interfaces, causing a characteristic decrease in the SPR signal. This allows sensing the presence of clinically relevant concentrations of lysozyme in undiluted serum samples.

Boron-based two-dimensional materials have extremely rich structures and excellent physical properties. Using a particle-swarm optimization (PSO) method and first-principles calculations, we performed a comprehensive search for the structure of a two-dimensional BeB2 monolayer. We found new configurations with lower energy compared with the previously reported α phase, namely the β, γ, and δ structures. Among those structures, the δ phase is found to have the lowest energy and we examined its dynamic as well as its thermodynamic stabilities. Then through strain engineering, we found a metal–semimetal transition in the α phase (under about 5% biaxial compressive strain) and in the δ phase (under about 3.2% and 7% biaxial tensile strain). As the compressive strain increases to 7%, the BeB2 sheets of the β phase and γ phase strongly twist, becoming more stable than the δ system. More interestingly, we found that Be atoms could penetrate the B atomic layer in the γ system under 2.5% tensile strain. All the predicted effects demonstrate the rich physical properties of the two-dimensional BeB2 monolayer.

Li-rich layered metal oxides (LNMO) receive significant attention as cathode materials of lithium-ion batteries owing to their higher specific energy density and lower cost compared with current commercial cathode materials. However, the stability of the structure during the cycle becomes a fatal weakness. In order to reduce the collapse of the structure during the cycle, previous researchers usually use cationic doping means, but all reported works have ignored the adverse effects from the destruction of the oxide layers that damages the structural integrity of the materials. In this work, from the perspective of a stable oxygen layer structure, we first dope sulfur into the oxygen layers of a lithium-rich cathode material to improve the structural stability and cycling performance. The preliminary calculation results of VASP prove that a small amount of sulfur doping is beneficial to stabilize the crystal structure of the material and balance the energy of the embedding and deintercalation of lithium ions, which provides theoretical guidance for our study. Further electrochemical results show that the sulfur-doped lithium-rich material released a higher initial efficiency of 96%, a specific capacity of 293.3 mA h g−1, and better cycling stability and rate performance (a capacity of 117 mA h g−1 is maintained at a current density of 5C). This work provides a new manner of doping for developing Li-rich layered metal oxide cathode materials that evade structural change.

The number of patients suffering from inflammatory bowel disease (IBD) is increasing worldwide. The development of noninvasive tests that are rapid, sensitive, specific, and simple would allow preventing patient discomfort, delay in diagnosis, and the follow-up of the status of the disease. Herein, we show the interest of vertically aligned nitrogen-doped carbon nanotube (VA-NCNT) electrodes for the required sensitive electrochemical detection of lysozyme in serum, a protein that is up-regulated in IBD. To achieve selective lysozyme detection, biotinylated lysozyme aptamers were covalently immobilized onto the VA-NCNTs. Detection of lysozyme in serum was achieved by measuring the decrease in the peak current of the Fe(CN)6(3-/4-) redox couple by differential pulse voltammetry upon addition of the analyte. We achieved a detection limit as low as 100 fM with a linear range up to 7 pM, in line with the required demands for the determination of lysozyme level in patients suffering from IBD. We attained the sensitive detection of biomarkers in clinical samples of healthy patients and individuals suffering from IBD and compared the results to a classical turbidimetric assay. The results clearly indicate that the newly developed sensor allows for a reliable and efficient analysis of lysozyme in serum.

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Significance How the van der Waals dispersion interaction relates to chemical electron-correlation effects presents a critical challenge to density functional theory development. Here, recently observed screening of the dispersion force between two insulating objects caused by the insertion of an intermediary graphene layer is explained in terms of Dobson’s general description of dispersion. This then provides a much-needed handle concerning how density functional approaches relate such long-range dispersion interactions to the subtleties of covalent bonding. Screening at intermediate distances appears to change the London expression from r−6 to r−7, an effect that becomes antiscreening (dispersion enhancement) at distances shorter than van der Waals contact. This provides basic insight into modern revelations that dispersion forces can outcompete covalent forces to control chemical structure., General properties of the recently observed screening of the van der Waals (vdW) attraction between a silica substrate and silica tip by insertion of graphene are predicted using basic theory and first-principles calculations. Results are then focused on possible practical applications, as well as an understanding of the nature of vdW attraction, considering recent discoveries showing it competing against covalent and ionic bonding. The traditional view of the vdW attraction as arising from pairwise-additive London dispersion forces is considered using Grimme’s “D3” method, comparing results to those from Tkatchenko’s more general many-body dispersion (MBD) approach, all interpreted in terms of Dobson’s general dispersion framework. Encompassing the experimental results, MBD screening of the vdW force between two silica bilayers is shown to scale up to medium separations as 1.25 de/d, where d is the bilayer separation and de is its equilibrium value, depicting antiscreening approaching and inside de. Means of unifying this correlation effect with those included in modern density functionals are urgently required.

Professional drivers have been characterized as experiencing heavy fatigue resulting from long driving time in their daily work. This study aimed to explore the potential demand of Fatigue Warning Systems (FWSs) among professional drivers as a means of reducing the danger of fatigue driving and to examine their opinions regarding the design of FWSs. Six focus groups with 35 participants and a questionnaire survey with 600 respondents were conducted among Chinese truck and taxi drivers to collect qualitative and quantitative data concerning the current situation of fatigue driving and opinions regarding the design of FWSs. The results revealed that both truck and taxi drivers had a positive attitude toward FWSs, and they hoped this system could not only monitor and warn them regarding their fatigue but also somewhat relieve their fatigue before they could stop and rest. As for warning signals, participants preferred auditory warnings, as opposed to visual, vibrotactile or electric stimuli. Interestingly, it was proposed that verbal warnings involving the information regarding consequences of fatigue driving or the wishes of drivers' family members would be more effective. Additionally, different warning patterns, including graded, single and continuous warnings, were discussed in the focus group. Finally, the participants proposed many other suggestions, as well as their concerns regarding FWSs, which will provide valuable information for companies who wish to develop FWSs for professional drivers.

In order to attain the distribution of hardness and austenite volume fraction in the induction hardening by the numerical simulation, the dilatometric curves of phase-transformation for 55CrMo steel were tested by the Gleeble-1500D thermal–mechanical simulator at the different heating rates. The volume fraction of austenite was evaluated using the level principle according to these curves. The regression analysis is performed to evaluate some parameters in the non-isothermal Johnson–Mehl–Avrami (JMA) equation. For 55CrMo steel, the phase-transformation activation energy Q = 7.264 × 105 J/mol, the phase-transformation kinetic parameters n = 1.2303, lnk0 = 78.7087. Using the JMA equation and the user subroutine developed in the paper, the distribution of austenite volume fraction and the hardness in the surface of the ball screw were obtained by the numerical simulation. The comparison of the calculation results and the experiment results shows that, the simulation results are consistent with the experiment results, the JMA equation and the user subroutine are valid, and the JMA equation can well describe the austenitization of 55CrMo steel. Keywords: Johnson–Mehl–Avrami equation, Dilatometric curves, Level principle, Numerical simulation, Induction hardening

Carbon/carbon composites, solely composed of pure carbon, are typical fiber fabric reinforced porous composites. They have been widely studied due to their excellent bio-inert performance and mechanical properties. However, their applications are restricted by two problems, i.e., easy dissociation of surface carbon particles and poor wettability of common bioactive coatings on their surface. To overcome these problems, we have adopted a biomimetic mineralization method, where Mg-doped hydroxyapatite particles were successfully prepared on hydroxyl-modified C/C surfaces, prepared via HNO3 oxidation. In this way, the original porous morphology of C/C, which is conducive to cell proliferation, is well-preserved. In the meanwhile, the introduction of electrochemical methods sped up the process of bio-mineralization and facilitated the construction of bone-like surface layers. In vivo tests revealed that 90 days after implantation for bone defect repair, the resulting C/C displayed unprecedented surface chemical stability and biocompatibility.

The detection of disease markers is considered an important step for early diagnosis of cancer. We design in this work a novel electrochemical sensing platform for the sensitive and selective detection of folic acid protein (FP). The platform is fabricated by electrophoretic deposition (EPD) of reduced graphene oxide (rGO) onto a gold electrode and post-functionalization of rGO with folic acid. Upon FP binding, a significant current decrease can be measured using differential pulse voltammetry (DPV). Using this scheme, a detection limit of 1pM is achieved. Importantly, the method also allows the detection of FP in serum being thus an appealing approach for the sensitive detection of biomarkers in clinical samples.

An easy and environmentally friendly method is described for the in situ synthesis of a reduced graphene oxide/gold nanoparticle (rGO/Au NPs) nanocomposite through the simultaneous reduction of GO and HAuCl4 using tyrosine in water. The rGO/Au NPs/Tyr nanocomposite has been characterized using different techniques such as UV-vis spectrometry, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurements. The electrocatalytic and catalytic activities of the resulting hybrid nanomaterial have been investigated for the nonenzymatic electrochemical detection of hydrogen peroxide (H2O2) and nitrophenol reduction, respectively. The sensor displayed a detection limit of 20 μM over a wide linear range from 0.02 to 25 mM with a sensitivity of 46.46 μM mM−1 cm−2. In addition, the sensor also showed good selectivity for H2O2 detection, long-term stability and reproducibility. Furthermore, the rGO/Au NPs/Tyr nanocomposite exhibited good catalytic activity toward 4-nitrophenol reduction.

To improve the distribution of the hardened layer and avoid potential defects, the effects of induction hardening parameters on the hardened layer were researched using the finite element method (FEM). A FEM model of single coil induction hardening was built, and temperature curves on the surface region of a ball screw were attained by numerical simulation. The hardenability and phase transformation of 55CrMo steel were researched by experiment. The simulation and experimental results show that the temperatures Ac1 and Ac3 rise with increasing heating rate. Non-uniformity of temperature at the groove region can lead to non-uniformity of austenitization and hardness. High temperature can result in cracks, coarse grain size and overheating defects at the groove tip. Martensite produced during cooling transforms into tempered martensite due to the residual heat, and the remaining austenite transforms into martensite at a low cooling rate. A 5010-type ball screw cannot attain a hardened layer with the thickness of 2.5 mm at the groove bottom without defects at the groove tip by single coil induction hardening. Multiple induction coils with a certain gap would be helpful to improve the uniformity of temperature and hardness. Keywords: Induction hardening, Austenitization, Hardness, Ball screw

The synthesis of carbon nanofibers (CNFS)/Co(OH)2 nanocomposites for non-enzymatic electrochemical sensing of glucose is presented. The sensing matrix was fabricated by electrophoretic deposition of a mixture of Co(NO3)2 and CNFS in ethanol at 50 V for 2 min onto gold electrodes. The formed CNFS/Co(OH)2 matrix was characterised by X-ray photoelectron spectroscopy, scanning electron microscopy and cyclic voltammetry. Its electrocatalytic properties towards the oxidation of glucose in 0.1 M NaOH were tested. A detection limit of 5 µM with linearity of 10 µM to 0.12 mM was obtained. The current response was selective towards glucose and stable over time. The good analytical performance of the nanocomposite allowed for sensing glucose in real human serum samples.

Fatigue among truck drivers has been studied extensively; however, less is known regarding the fatigue experience of taxi drivers in heavily populated metropolitan areas. This study aimed to compare the differences and similarities between truck and taxi driver fatigue to provide implications for the fatigue management and education of professional drivers.A sample of 274 truck drivers and 286 taxi drivers in Beijing was surveyed via a questionnaire, which included items regarding work characteristics, fatigue experience, accident information, attitude toward fatigue, and methods of counteracting fatigue.Driver fatigue was prevalent among professional drivers, and it was even more serious for taxi drivers. Taxi drivers reported more frequent fatigue experiences and were involved in more accidents. Among the contributing factors to fatigue, prolonged driving time was the most important factor identified by both driver groups. Importantly, the reason for the engagement in prolonged driving was neither due to the lack of awareness concerning the serious outcome of fatigue driving nor because of their poor detection of fatigue. The most probable reason was the optimism bias, as a result of which these professional drivers thought that fatigue was more serious for other drivers than for themselves, and they thought that they were effective in counteracting the effect of fatigue on their driving performance. Moreover, truck drivers tended to employ methods that require stopping to counteract fatigue, whereas taxi drivers preferred methods that were simultaneous with driving. Although both driver groups considered taking a nap as one of the most effective means to address fatigue, this method was not commonly used. Interestingly, these drivers were aware that the methods they frequently used were not the most effective means to counteract fatigue.This study provides knowledge on truck and taxi drivers' characteristics in fatigue experience, fatigue attitude, and fatigue countermeasures, and these findings have practical implications for the fatigue management and education of professional drivers.

The paper reports on the simultaneous reduction/deposition of reduced graphene oxide/copper nanoparticles (rGO/Cu NPs) on a glass/Ti/Au electrode using an electrophoretic deposition (EPD) technique from a colloidal suspension of graphene oxide (GO) and copper sulphate (CuSO4) in ethanol. The method allows controlling the nanoparticle density by adjusting the deposition time. Structural characterization and chemical composition analysis of the modified electrode showed the simultaneous reduction of GO with the concomitant deposition of metallic CuNPs with a Cu(OH)2 shell. The electrocatalytic activity of the modified electrode was evaluated for non-enzymatic glucose sensing in alkaline medium. While the Au electrode modified only with rGO did not show obvious electrocatalytic activity, the electrode coated with rGO/CuNPs exhibited excellent electrocatalytic behavior towards glucose oxidation with a high sensitivity of 447.65 μA mM−1 cm−2. The response current of the sensor is linear to glucose concentrations up to 1.2 mM with a detection limit of 3.4 μM. Furthermore, the interference from various oxidizable molecules such as dopamine, uric acid, ascorbic acid and carbohydrate molecules such as fructose, lactose and galactose was negligible, indicating a good selectivity of detection. The application of this glucose sensor in real samples has also been demonstrated successfully.

The quantification of peroxynitrite (ONOO−, PON) and hydrogen peroxide (H2O2) is intrinsically difficult as both species show similar oxidative features located within a narrow potential. The sub-second lifetime of ONOO− at neutral pH further complicates the analysis. In this paper, we examine the electrocatalytic activity of cobalt phthalocyanine tetracarboxylic acid (CoPc–COOH) loaded reduced graphene oxide (rGO) films towards peroxynitrite and hydrogen peroxide detection. The rGO/CoPc–COOH matrix is synthesized by the reaction of graphene oxide (GO) and CoPc–COOH at 90 °C for 5 h under ultrasonication. The integration of CoPc–COOH and the reduction of GO to rGO was confirmed by X-ray photoelectron spectroscopy, FTIR, Raman, UV-vis spectroscopy and electrochemistry. The rGO/CoPc–COOH film showed high electrocatalytic activity and specificity for ONOO− at anodic potential with a sensitivity of ≈11.5 ± 1 nA nM−1 and a peroxynitrite detection limit of ≈1.7 nM. The rGO/CoPc–COOH films further exhibited electrocatalytic reduction of H2O2 with a sensitivity of 14.5 μA mM−1 and a detection limit of ≈60 μM for H2O2.

Acute lung injury (ALI) is a serious respiratory syndrome featured with uncontrolled inflammatory response. Biochanin A has been showed to possess and anti-inflammatory effect. This study intended to explore the suppression of biochanin A on lipopolysaccharide (LPS)-induced ALI in mice. Seven hours later LPS-induced ALI model established, the indexes including, pathological changes, MPO activity, wet/dry ratio, proinflammatory cytokines TNF-α, IL-1β, and IL-6, production, as well as and TLR4/NF-κB and PPAR-γ signaling pathway expression were compared bwtween different groups. In addition, bronchoalveolar lavage fluid (BALF) was collected and the levels of total protein, inflammatory cells and TNF-α, IL-1β, and IL-6 were detected. The results revealed that LPS lead to significantly lung pathological injury, and damage of lung vascular permeability showing by higher lung wet/dry ratio and total protein levels in the BALF when compared to the control group mice. However, these changes significantly reversed by biochanin A. Moreover, the levels of inflammatory cells in BALF, proinflammatory cytokines TNF-α, IL-1β, and IL-6, in both lung and BALF were also dose-dependently reduced by biochanin A during ALI process. To investigate the anti-inflammatory mechanisms of biochanin A, we found that biochanin A significantly inhibited the activation of TLR4/NF-κB signaling pathway induced by LPS. Furthermore, the expression of PPAR-γ also markedly increased in the mice after treated with biochanin A. In conclusion, biochanin A alleviated LPS-induced ALI by inhibiting the inflammatory response, which was mediated via down-regulating the activation of TLR4/NF-κB signaling pathway and enhancing the expression of PPAR-γ.

A sensitive and stable non-enzymatic sensing platform for D-glucose based on a reduced graphene oxide (rGO) matrix modified with Ni(OH)2 nanostructures was established. The sensing matrix was fabricated in one-step through an electrophoretic deposition approach. It is based on the mixing of negatively charged graphene oxide (GO) with nickel ions resulting in a positively charged composite making cathodic electrophoretic deposition possible. The thickness of the resulting rGO/Ni(OH)2 matrix deposited on Au could be controlled by varying the time of electrophoretic deposition. The rGO/Ni(OH)2 matrix was characterized by X-ray photoelectron spectroscopy, Raman spectroscopy and cyclic voltammetry. The rGO/Ni(OH)2 electrodes exhibited excellent electrocatalytic behaviour towards glucose oxidation in alkaline medium. The response current of the sensor is linear to glucose concentrations from 15 μM to 30 mM with a sensitivity of 11.4 ± 0 mA cm−2 mM−1. The interface was much more stable than drop-cast films. These results pave the way for electrophoretic deposition as a competitive alternative over drop-casting for the fabrication of rGO modified interfaces.

A sensitive electrochemical active interface for sugar sensing based on the specific boronic acid-diol binding was established. The sensing matrix was formed by stirring a suspension of graphene oxide (GO) with 4-aminophenylboronic acid (APBA). The resulting composite consists of a water insoluble precipitate of reduced graphene oxide (rGO) with APBA incorporated into the rGO matrix. Differential pulse voltammetry (DPV) on glassy carbon electrodes modified with rGO/APBA was used for the detection of fructose, mannose and glucose. The fabricated sensor exhibited a wide linear range with detection limits of 100 nM for fructose, and around 800 nM for mannose and glucose.

The diamond single crystal, synthesized with Fe–Ni–C–B system of catalyst under high temperature and high pressure, had been observed by field emission scanning electron microscope and transmission electron microscope. The presence of a cellular structure suggested that the diamond grew from melted catalyst solution and there existed a zone of component supercooling zone in front of the solid–liquid interface. The main impurities in the diamond crystal was (FeNi) 23 C 6 . The triangle screw pit revealed on the (111) plane was generated by the screw dislocation meeting the diamond (111) plane at the points of emergence of dislocations. A narrow twin plane was formed between the two (111) plane.

The simultaneous detection of tryptophan and tyrosine by electrochemical means is not trivial as both amino acids display comparable oxidation potentials. Here, we show that simultaneous detection of both amino acids can be achieved on boron-doped diamond (BDD) electrodes and wires when the ratio of tryptophan/tyrosine is ≤0.5. The possibility to detect quantitatively tryptophan and tyrosine in human blood serum samples was investigated. Keywords: Boron-doped diamond electrodes (BDD), BDD nanowires, Tryptophan, Tyrosine, Differential pulse voltammetry, Human blood serum

Herein, we report on the simultaneous reduction and functionalization of graphene oxide (GO) with environmentally friendly tyrosine through the direct reaction of GO with tyrosine (Tyr) at 100 °C for 24 h. The resultant material (rGO/Tyr) has been characterized using UV-vis spectrometry, FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. The rGO/Tyr nanomaterial displayed good electrocatalytic activity for the detection of hydrogen peroxide (H2O2) with a wide linear range from 100 µM to 2.1 mM, a detection limit of 80 µM and a sensitivity of 69.07 µA mM−1 cm−2. In addition, the rGO/Tyr electrode showed good selectivity for H2O2 detection in the presence of uric acid, ascorbic acid, dopamine and glucose.

In this paper the fabrication of micrometer long boron-doped diamond nanowire (L-BDD NWs) electrodes is reported. The diamond nanowires were obtained by a maskless reactive ion etching process with oxygen plasma using 15 μm thick polycrystalline boron-doped diamond (BDD) films as starting material. The resulting nanowire interfaces showed enhanced electrochemical activity towards the direct electrochemical detection of glucose under strong basic (pH 12) condition when compared to flat BDD and short nanowires (S-BDD NWs). The robust response of these nanostructures with a detection limit of 60 μM and a linear range up to 8 mM and the ease of formation make L-BDD NWs a promising platform for real time applications. Keywords: Boron-doped diamond, Nanowires, Glucose, Non-enzymatic, Sensing

© 2017 Elsevier Inc. All rights reserved. Practical aspects are considered that users need to know in choosing computational methods and conceptual ideas for understanding surface adsorption embodying some degree of van der Waals dispersive attractions. Emphasized is the unique chemistry that results when these forces are strong and mix with traditional covalent or ionic bonding mechanisms to control chemical outcomes. Indeed, many methods are being developed to provide accurate descriptions of surface adsorption, including those based on ab initio and density-functional-theory (DFT) approaches. Accurate methods like coupled-cluster theory (CC), the random-phase approximation (RPA), and time-dependent DFT (TDDFT) are demanded when the critical interactions are weak, but these methods are computationally expensive, scaling formally at least as order n6 in system size (though efficient modern algorithms can reduce that to, e.g., order n4logn or even to linear scaling). How such methods can be applied to large systems is discussed, but more focus is given to more approximate, faster approaches, especially: the empirical pairwise additive D3 correction of Grimme et al., the van der Waals density functional approach of Dion et al. (vdW-DF), and the new semiempirical many-body dispersion (MBD) method of Tkatchenko et al. Fundamental understanding of all methods is provided by describing the way they behave in the very short range (unified atom) and very long range asymptotic limits, using Dobson's classification scheme. How simple computational methods can give realistic adsorption energies and structures for close-contact interactions whilst providing very poor descriptions of these asymptotic limits is examined. Four strong-interaction test systems are considered: the adsorption of benzene on coinage metals, the adsorption of 1,10-phenanthroline (PHEN) on Au(111), the adsorption of large tetraalkylporphyrin molecules on graphite from organic solution, and the nature of the Au-S bonds found on gold surfaces and nanoparticles protected by sulfur compounds. For adsorption energies, the vdW-DF method is found to be cumbersome and unreliable, the MBD method to be accurate but often prohibitively expensive, and the D3 method to be computationally efficient and, for the considered examples, highly reliable. Alternatively, neglect of dispersion interactions is found to lead to poor understanding of all important chemical properties.

International audience; The fast and efficient elimination of pathogenic bacteria from water, food or biological samples such as blood remains a challenging task. Magnetic isolation of bacteria from complex media holds particular promise for water disinfection and other biotechnological applications employing bacteria. When it comes to infectious diseases such as urinary tract infections, the selective removal of the pathogenic species in complex media such as human serum is also of importance. This issue can only be accomplished by adding pathogen specific targeting sites onto the magnetic nanostructures. In this work, we investigate the potential of 2-nitrodopamine modified magnetic particles anchored on reduced graphene oxide (rGO) nanocomposites for rapid capture and efficient elimination of E. coli associated with urinary tract infections (UTIs) from water and serum samples. An optimized magnetic nanocarrier achieves a 99.9% capture efficiency even at E. coli concentrations of 1 × 10 1 cfu mL −1 in 30 min. In addition, functionalization of the nanostructures with poly(ethylene glycol) modified pyrene units and anti-fimbrial E. coli antibodies allowed specific elimination of E. coli UTI89 from serum samples. Irradiation of the E. coli loaded nanocomposite with a near-infrared laser results in the total ablation of the captured pathogens. This method can be flexibly modified for any other pathogenic bacteria, depending on the antibodies used, and might be an interesting alternative material for a magnetic-based body fluid purification approach.

The halogenated boron-doped diamond (BDD) surfaces were reacted with sodium azide through a nucleophilic substitution reaction. The resulting azide-terminated BDD surfaces were used to trigger the “click” reaction. Because of the attractive electrochemical properties of ferrocene-containing molecules, such as fast electron transfer rates, reversible redox activities, and favorable redox potentials, we show that ferrocene derivatives can be grafted onto non-oxidized diamond surfaces by “click chemistry”. These redox-active ferrocene-containing layers on a BDD surface, because of their ability to store and release charges reversibly, have the potential to be used as hybrid molecular/semiconductor memory devices. The halogenated boron-doped diamond surfaces were reacted with sodium azide through a nucleophilic substitution reaction. The resulting azide-terminated boron-doped diamond surfaces (N3-BDD) were used to trigger the “click” reaction. We show here that ferrocene derivatives can be grafted onto non-oxidized diamond surfaces by “click chemistry”. These redox-active ferrocene-containing layers on a boron-doped diamond (BDD) surface, because of their ability to store and release charges reversibly, have the potential to be used as hybrid molecular/semiconductor memory devices.

The controlled release of biomolecules from a substrate surface is a challenging task. Photocleavable linkers appear as attractive candidates for light-triggered delivery. We show here the possibility of creating photoactivable diamond nanowire interfaces, from which molecules can be photochemically released upon irradiation at 365 nm for several minutes. The approach is based on the covalent modification of boron-doped diamond nanowires (BDD NWs) with o-nitrobenzyl containing ligands, to which different biomolecules can be attached via amide bond formation. The photodecomposition reaction and the subsequent release of small proteins such as lysozyme or enzymes such as horseradish peroxidase (HRP) are investigated using electrochemical impedance spectroscopy. Using a colorimetric assay, we demonstrate that, while complete cleavage of HRP was achieved upon irradiation for 10 min at 1 W cm(-2), this exposure time resulted in a partial loss of enzymatic activity.

H-terminated DLC layers were synthesized on SiO2 substrate by radio frequency (RF) magnetron plasma-enhanced chemical vapor deposition (PECVD) in a conventional reactor using C4H10 as carbon source. As-deposited DLC films were characterized by Raman spectroscopy, scanning electron microscopy (SEM) as well as atomic force microscopy (AFM). The chemical reactivity of the obtained DLC surface was further investigated by exposing the photochemically oxidized DLC surface to a silane reagent. The course of the reaction was followed using water contact angle and X-ray photoelectron spectroscopy.

Diamond-like carbon (DLC) films have excellent mechanical and chemical properties similar to those of crystalline diamond giving them wide applications as protective coatings. So far, a variety of methods are employed to deposit DLC films. In this study, DLC films with different thicknesses were deposited on Si and glass substrates using RF magnetron PECVD method with C4H10 as carbon source. The bonding microstructure, surface morphology and tribological properties at different growing stages of the DLC films were tested. Raman spectra were deconvoluted into D peak at about 1370 cm−1 and G peak around 1590 cm−1, indicating typical features of the DLC films. A linear relationship between the film thickness and the deposition time was found, revealing that the required film thickness may be obtained by the appropriate tune of the deposition time. The concentration of sp3 and sp2 carbon atoms in the DLC films was measured by XPS spectra. As the films grew, the sp3 carbon atoms decreased while sp2 atoms increased. Surface morphology of the DLC films clearly showed that the films were composed of spherical carbon clusters, which tended to congregate as the deposition time increased. The friction coefficient of the films was very low and an increase was also found with the increase of film thickness corresponding to the results of XPS spectra. The scratch test proved that there was good bonding between the DLC films and the substrates.

In this article, we report on the low-level detection of hydrogen peroxide, a key player in the redox signaling pathway and a toxic product in the cellular system, using a colorimetric solution assay. Amine-terminated undoped nanocrystalline diamond thin films were grown on glass using a linear-antenna microwave plasma CVD process. The diamond surface consists mainly of -NH(2) termination. The aminated diamond surface was decorated with horseradish peroxidase (HRP) enzyme using carbodiimide coupling chemistry. The success of the HRP immobilization was confirmed by X-ray photoelectron spectroscopy (XPS). The enzymatic activity of immobilized HRP was determined with a colorimetric test based on the HRP-catalyzed oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sufonic acid (ABTS) in the presence of hydrogen peroxide. The surface coverage of active HRP was estimated to be Γ = 7.3 × 10(13) molecules cm(-2). The use of the functionalized diamond surface as an optical sensor for the detection of hydrogen peroxide with a detection limit of 35 nM was demonstrated.

While it is clearly established that oxidation of as-grown boron-doped diamond (BDD) interfaces results in the introduction of different surface oxygen functions such as ether, carbonyl and hydroxyl groups, there is no reported approach which can clearly distinguish between the different surface functions. For further surface functionalization, it is important to quantify the presence of each group on the diamond surface. In this paper, the presence and amount of surface hydroxyl groups is identified using esterification of the COH groups with trifluoroacetic acid. The presence of CF3 group in the acid allowed the identification and estimation of the amount of surface hydroxyl groups using X-ray photoelectron spectroscopy (XPS). Keywords: Boron-doped diamond, Oxidation, Hydroxyl groups, Esterification