A bioelectronic sensor based on canine olfactory nanovesicle-carbon nanotube hybrid structures for the fast assessment of food quality

We developed an olfactory-nanovesicle-fused carbon-nanotube-transistor biosensor (OCB) that mimics the responses of a canine nose for the sensitive and selective detection of hexanal, an indicator of the oxidation of food. OCBs allowed us to detect hexanal down to 1 fM concentration in real-time. Significantly, we demonstrated the detection of hexanal with an excellent selectivity capable of discriminating hexanal from analogous compounds such as pentanal, heptanal, and octanal. Furthermore, we successfully detected hexanal in spoiled milk without any pretreatment processes. Considering these results, our sensor platform should offer a new method for the assessment of food quality and contribute to the development of portable sensing devices.     

Controlled assembly of Ag nanoparticles and carbon nanotube hybrid structures for biosensing

Here we report a chemical-free, simple, and novel method in which a part from a silver-based anode is controllably used in a straightforward manner to produce silver nanoparticles (Ag NPs) in order to fabricate a controlled assembly of Ag NPs and single walled carbon nanotube (SWCNT) hybrid structures. The attachment and distribution of Ag NPs along SWCNTs have been investigated and characterized by field emission scanning electron microscopy (FESEM). We have achieved the decoration of SWCNTs with different densities of Ag NPs by changing the deposition time, the applied voltage, and the location of carbon nanotubes with respect to the anode. At low voltage, single silver nanoparticle is successfully attached at the open ends of SWCNTs whereas at high voltage, intermediate and full coverage densities of Ag NPs are observed. As voltage is further increased, fractals of Ag NPs along SWCNTs are observed. In addition, a device based on a Ag NPs-SWNT hybrid structure is used for the label-free detection of ssDNA molecules immobilized on it. We believe that the proposed method can be used to decorate and/or assemble metal nanoparticles or fractal patterns along SWCNTs with different novel metals such as gold, silver, and copper and can be exploited in various sensitive applications for fundamental research and nanotechnology.     

Flow injection based microfluidic device with carbon nanotube electrode for rapid salbutamol detection

A microfabicated flow injection device has been developed for in-channel electrochemical detection (ECD) of a β-agonist, namely salbutamol. The microfluidic system consists of PDMS (polydimethylsiloxane) microchannel and electrochemical electrodes formed on glass substrate. The carbon nanotube (CNT) on gold layer as working electrode, silver as reference electrode and platinum as auxiliary electrode were deposited on a glass substrate. Silver, platinum, gold and stainless steel catalyst layers were coated by DC-sputtering. CNTs were then grown on the glass substance by thermal chemical vapor deposition (CVD) with gravity effect and water-assisted etching. 100-μm-deep and 500-μm-wide PDMS microchannels fabricated by SU-8 molding and casting were then bonded on glass substrate by oxygen plasma treatment. Flow injection and ECD of salbutamol was performed with the amperometric detection mode for in-channel detection of salbutamol. The influences of flow rate, injection volume, and detection potential on the response of current signal were optimized. Analytical characteristics, such as sensitivity, repeatability and dynamic range have been evaluated. Fast and highly sensitive detection of salbutamol have been achieved. Thus, the proposed combination of the efficient CNT electrode and miniaturized lab-on-a-chip is a powerful platform for β-agonists detection.     

Liquid-crystalline hybrid materials based on [60]fullerene and bent-core structures

What a core-ker! By the appropriate combination of promesogenic bent-core structures and the C(60) unit, lamellar polar liquid-crystal phases were induced. The supramolecular organization of the functional fullerene-based assemblies, the temperature range of the soft phase, the stabilization of the mesophase-like order at room temperature, and the molecular switching under an electric field can be tuned, depending on the molecular structure.     

"Inosaminoacids": novel inositol-amino acid hybrid structures accessed by microbial arene oxidation

Microbial 1,2-dihydroxylation of sodium benzoate permits the rapid construction of novel inositol-amino acid hybrid structures. Both β- and γ-amino acids are accessible by means of an acylnitroso Diels-Alder cycloaddition.     

Facile strategy of fabricating multifunctional hydrogel with high performance based on hybrid graphene oxide and carbon nanotube

Here we report a facile strategy of fabricating multifunctional polyacrylamide(PAM) hydrogels based on hybrid graphene oxide (GO) sheets and carbon nanotubes (CNTs). Compared to original PAM hydrogels cross-linked chemically with N,N-methylenebisacrylamide (BIS), the hybrid hydrogels exhibit high mechanical strength (strength > 90?kPa and broken strain > 2000%), well adhesion, environmental stability, dye-loading capacity, and excellent self-healing property. This study provides a new insight for the preparation of functionalized hydrogels with carbon nano-materials, and the resultant material shows very promising performance for a range of applications.     

Novel electroactive and photoactive molecular materials based on conjugated donor-acceptor structures for optoelectronic device applications

Four donor-acceptor functionalized molecular materials with symmetrical structures have been synthesized and investigated for their use in optoelectronic applications. These pi-conjugated molecules consist of one electron-donating moiety, for instance, carbazole, triphenylamine, or phenothiazine at the center, and two acceptors at each side. Introduction of different donor moieties decreases the band gaps allowing a fine-tuning of the optical and electrical properties. These materials exhibit multifunctional properties, such as a red light-emitting behavior and a large photovoltaic effect. Red organic light-emitting diodes were fabricated in a facile nondoping configuration based on these materials. Saturated red-emission is observed with a CIE of x = 0.64 and y = 0.33, and an external quantum efficiency of 0.19%. In addition, our first observation of photovoltaic response in the pi-conjugated molecule with donor-acceptor-donor structure is reported. The organic single-component photovoltaic cells were fabricated and characterized. Their open-circuit voltage and short-circuit current density are 1.1 V and 0.07 mA cm(-2), respectively. The photovoltaic effect corresponds to the absorption characteristics of the compound and depends on the nature of the electron-donating group.     

Self-assembled hybrid polymer-TiO2 nanotube array heterojunction solar cells

Films comprised of 4 microm long titanium dioxide nanotube arrays were fabricated by anodizing Ti foils in an ethylene glycol based electrolyte. A carboxylated polythiophene derivative was self-assembled onto the TiO2 nanotube arrays by immersing them in a solution of the polymer. The binding sites of the carboxylate moiety along the polymer chain provide multiple anchoring sites to the substrate, making for a stable rugged film. Backside illuminated liquid junction solar cells based on TiO2 nanotube films sensitized by the self-assembled polymeric layer showed a short-circuit current density of 5.5 mA cm-2, a 0.7 V open circuit potential, and a 0.55 fill factor yielding power conversion efficiencies of 2.1% under AM 1.5 sun. A backside illuminated single heterojunction solid state solar cell using the same self-assembled polymer was demonstrated and yielded a photocurrent density as high as 2.0 mA cm-2. When a double heterojunction was formed by infiltrating a blend of poly(3-hexylthiophene) (P3HT) and C60-methanofullerene into the self-assembled polymer coated nanotube arrays, a photocurrent as high as 6.5 mA cm-2 was obtained under AM 1.5 sun with a corresponding efficiency of 1%. The photocurrent action spectra showed a maximum incident photon-to-electron conversion efficiency (IPCE) of 53% for the liquid junction cells and 25% for the single heterojunction solid state solar cells.     

Synthesis and structures of two three-dimensional hybrid materials based on vanadium polyoxoanions and macrocyclic metal complexes

Transition Metal Chemistry - The reactions of transition metal macrocyclic complexes [ML](ClO4)2 (L?=?1,8-diethyl-1,3,6,8,10,13-hexaazacyclotetradecane, M=Ni, Cu) with NH4VO3 gave two...     

Modelling carbon nanotube based biosensor

This paper presents a two-dimensional-in-space mathematical model of an amperometric biosensor based on an enzyme-loaded carbon nanotubes layer deposited on a perforated membrane. The developed model is based on non-linear non-stationary reaction-diffusion equations. By changing input parameters the output results are numerically analysed with a special emphasis to the influence of the geometry and the catalytic activity of the biosensor to its response. The numerical simulation at transition and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and experimental data was admissible at different concentrations of the substrate and the mediator.     

Growth of well-aligned carbon nanotube structures in successive layers

Layered structures of well-aligned carbon nanotubes were grown using three variations of vapor-phase chemical vapor deposition growth processes. The reactants (typically ferrocene and benzene) were introduced either directly to a heated furnace or carried into the furnace by evaporation or spray pyrolysis in an argon flow. Thick mats of densely packed, well-aligned nanotubes were produced when the reactants were continuously introduced to the reaction; however, when the reactant flow was interrupted, the pauses allowed growth to stop and then restart as a new layer. These pauses were achieved by either completely stopping the reactant flow for a given time or by modifying the dispensing system to introduce the reactants in discrete drops. Time intervals between drops were varied between 20 s and 120 s, with distinct layers observed for pauses of 30 s or greater. The best results were achieved when drops of a catalyst-rich solution were alternated with drops of pure benzene. Layers were grown with thicknesses ranging from several microns to several hundred microns, and structures were grown with well over 100 layers.     

A microfabricated hybrid device for DNA sequencing

We have created a hybrid device of a microfabricated round-channel twin-T injector incorporated with a separation capillary in order to extend the straight separation distance for high speed and long readlength DNA sequencing. Semicircular grooves on glass wafers are obtained using a photomask with a narrow line-width and a standard isotropic photolithographic etching process. Round channels are made when two etched wafers are face-to-face aligned and bonded. A two-mask fabrication process has been developed to make channels of two different diameters. The twin-T injector is formed by the smaller channels whose diameter matches the bore of the separation capillary, and the "usual" separation channel, now called the connection channel, is formed by the larger ones whose diameter matches the outer diameter of the separation capillary. The separation capillary is inserted through the connection channel all the way to the twin-T injector to allow the capillary bore flush with the twin-T injector channels. The total dead-volume of the connection is estimated to be approximately 5 pL. To demonstrate the efficiency of this hybrid device, we have performed four-color DNA sequencing on it. Using a 200 microm twin-T injector coupled with a separation capillary of 20 cm effective separation distance, we have obtained readlengths of 800 plus bases at an accuracy of 98.5% in 56 min, compared to about 650 bases in 100 min on a conventional 40 cm long capillary sequencing machine under similar conditions. At an increased separation field strength and using a diluted sieving matrix, the separation time has been reduced to 20 min with a readlength of 700 bases at 98.5% base-calling accuracy.     

Solar-microbial hybrid device based on oxygen-deficient niobium pentoxide anodes for sustainable hydrogen production

Hydrogen gas is emerging as an attractive fuel with high energy density for the direction of energy resources in the future. Designing integrated devices based on a photoelectrochemical (PEC) cell and a microbial fuel cell (MFC) represents a promising strategy to produce hydrogen fuel at a low price. In this work, we demonstrate a new solar-microbial (PEC–MFC) hybrid device based on the oxygen-deficient Nb₂O₅ nanoporous (Nb₂O_5–x NPs) anodes for sustainable hydrogen generation without external bias for the first time. Owing to the improved conductivity and porous structure, the as-prepared Nb₂O_5–x NPs film yields a remarkable photocurrent density of 0.9 mA cm^–2 at 0.6 V (vs. SCE) in 1 M KOH aqueous solution under light irradiation, and can achieve a maximum power density of 1196 mW m^–2 when used as an anode in a MFC device. More importantly, a solar-microbial hybrid system by combining a PEC cell with a MFC is designed, in which the Nb₂O_5–x NPs electrodes function as both anodes. The as-fabricated PEC–MFC hybrid device can simultaneously realize electricity and hydrogen using organic matter and solar light at zero external bias. This novel design and attempt might provide guidance for other materials to convert and store energy.     

Evaluating the effect of addition of nanodiamond on the synergistic effect of graphene-carbon nanotube hybrid on the mechanical properties of epoxy based composites

Addition of carbon nanotubes (CNT) to Graphene (Gr) is seen to have synergistic effect as reinforcement to polymer matrix. This is possible as CNTs inhibit stacking of Gr sheets, thus providing larger surface area nanophase to get bonded with polymer matrix and providing mechanical support through load sharing and crack growth inhibition. However, tube like morphology and high aspect ratio of CNT often lead to entanglement, which restricts their effect in exfoliating Gr. The aim of the present study is to investigate the potential of ND in improving the synergistic effect of Gr-CNT hybrid as a reinforcement to epoxy matrix. This study utilizes the power of ultrasonication technique, which is very simple and scalable, for dispersing and incorporating nanofillers into epoxy matrix. Addition of ND to Gr-CNT epoxy composite improved the tensile strength from ~46% with 0.5 wt% (75Gr:25ND) to ~51% with 0.8 wt% (25Gr:25CNT:50ND) as compared to neat epoxy. While the fracture toughness improved from ~140% with 0.5 wt% (25Gr:75CNT) to 165% with 0.8 wt% (25Gr:50CNT:25ND). Fractured surfaces of composites revealed improved dispersion and strong interfacial interaction with addition of ND to Gr-CNT hybrid. NDs attaches to the surface of Gr inhibit the stacking of Gr sheets by restricting π-π stabilization. NDs also help in bridging the ends of CNTs together into long chains, thereby increasing the aspect ratio of the fiber like reinforcement. This increases the total available surface area of CNTs and Gr, to interact with epoxy matrix, improves the overall efficiency of Gr-CNT hybrid as a reinforcement, resulting into improvement in mechanical properties of the composite structure.     

A biomimetic "polysoap" for single-walled carbon nanotube dispersion

As-synthesized single-walled carbon nanotubes (SWNTs) are bundled mixtures of different species. The current challenge in the field of carbon nanotube research lies in the processing and separation of SWNTs, which first require efficient dispersion of individual SWNTs in solvents. We report DNA-mimicking polysoap surfactants that disperse SWNTs in aqueous solutions more effectively than DNA. The polysoaps are synthesized by functionalizing the side chain of poly(styrene-alt-maleic acid) with aminopyrene. The synthetic nature of the polysoap opens a new approach to further optimization of not only SWNT dispersion efficiency but also multi-functional SWNT dispersing surfactant.     

Construction of a carbon nanotube/diamond hybrid functionalized electrode surface

Multiwalled carbon nanotubes were attached to the surface of boron-doped diamond by electropolymerization using a bridge of polyaniline. A carbon nanotube/diamond hybrid functionalized surface was obtained and testified by field emission scanning electron microscopy. The electrochemical impedance spectroscopy and cyclic voltammetry measurements revealed that this carbon hybrid surface possessed low electron-transfer resistance, large double-capacitance value, and high electrocatalytic ability. This indicated that this functionalized surface had a variety of potential sustainable technology applications such as in supercapacitors, biomolecule-sensing devices.     

Synthesis and crystal structures of four three-dimensional hybrid materials based on polyoxovanadate bridging macrocyclic copper/nickel complexes

Transition Metal Chemistry - In this research, four hybrid materials, namely [Ni(MC)]3[VO3]6·12.25H2O (1), [Cu(MC)]3[VO3]6 (2), [Ni(PC)]3[VO3]6·2H2O (3), and [Cu(PC)]3[VO3]6·2H2O (4)...     

Inorganic-organic hybrid compounds based on octamolybdates and multidentate N-donor ligand: syntheses, structures, photoluminescence and photocatalysis

Six inorganic-organic hybrid compounds, namely, [Cu(2)(2,4'-tmbpt)(2)(β-Mo(8)O(26))(H(2)O)(2)]·7H(2)O (), [Cu(2,4'-tmbpt)(γ-Mo(8)O(26))(0.5)(H(2)O)]·H(2)O (), [Co(2,4'-Htmbpt)(2)(γ-Mo(8)O(26))(H(2)O)(2)] (), [Zn(2,4'-Htmbpt)(2)(γ-Mo(8)O(26))(H(2)O)(2)] (), [Ni(2,4'-tmbpt)(α-Mo(8)O(26))(0.5)(H(2)O)]·2.5H(2)O () and [Ag(2,4'-Htmbpt)(β-Mo(8)O(26))(0.5)] (), have been synthesized under hydrothermal conditions (2,4'-tmbpt = 1-((1H-1,2,4-triazol-1-yl)methyl)-3-(2-pyridyl)-5-(4-pyridyl)-1,2,4-triazole). The structures of compounds have been determined by single-crystal X-ray diffraction analyses and characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD) analyses and thermogravimetric analyses (TGA). Compound shows a 3D (3,4)-connected framework constructed by the 2D Cu(ii)-organic fragments and [β-Mo(8)O(26)](4-) anions. Compound exhibits a 2D layer structure based on Cu(ii)-organic chains and [γ-Mo(8)O(26)] chains. The layers are extended into a 3D supramolecular framework by hydrogen-bonding interactions. Compounds and are isostructural, and display 1D chain structures. The chains are further interlinked by hydrogen-bonding interactions to form 3D supramolecular architectures. Compound shows a 3D framework based on the 2D Ni(ii)-organic fragments and [α-Mo(8)O(26)](4-) anions. In compound , the 1D chains constructed by the Ag(i) ions, 2,4'-Htmbpt ligands and [β-Mo(8)O(26)](4-) anions are extended by hydrogen-bonding interactions into a 2D supramolecular layer. Each layer threads into the adjacent layers, yielding a 2D → 3D interdigitated structure. Moreover, the photoluminescent properties of and , the optical band gaps of , and the photocatalytic properties of have also been investigated.