The construction of molecular machines has captured the imagination of scientists for decades. Despite significant progress in the synthesis and studies of the properties of small-molecule components (smaller than 2-5 kilo Dalton), challenges regarding the incorporation of molecular components into real devices are still eminent. Nano-sized molecular machines operate the complex biological machinery of life, and the idea of mimicking the amazing functions using artificial nano-structures is intriguing. Both in small-molecule molecular machine components and in many naturally occurring molecular machines, mechanically interlocked molecules and structures are key functional components. In this work, we describe our initial efforts to interface mechanically-interlocked molecules and gold-nanoparticles (AuNPs); the molecular wire connecting the AuNPs is covered in an insulating rotaxane-layer, thus mimicking the macroscopic design of a copper wire. Taking advantage of recent progress in the preparation of supramolecular complexes of the cucurbit[7]uril (CB[7]) macrocycle, we have prepared a bis-thiol functionalised pseudo-rotaxane that enables us to prepare a AuNP-stoppered [2]rotaxane in water. The pseudo-rotaxane is held together extremely tightly (Ka > 1013 M-1), Ka being the association constant. We have studied the solution and gas phase guest-host chemistry using NMR spectroscopy, mass spectroscopy, and electrochemistry. The bis-thiol functionalised pseudo-rotaxane holds further a ferrocene unit in the centre of the rotaxane; this ferrocene unit enables us to address the system in detail with and without CB[7] and AuNPs using electrochemical methods.

A novel nitrite (NO2-) sensor was fabricated by electrodepositing phosphotungstic acid (PW12O403-) on chitosan (CHIT)-graphene nanocomposites modified cysteamine/gold (Au) electrode. Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were used to study the CHIT-graphene nanocomposites and the PW12O403-/CHIT-graphene/cysteamine/Au electrode. Cyclic voltammograms and chronoamperometric were used to evaluate electrochemical and electrocatalytic properties of the PW12O403-/CHIT-graphene/cysteamine/Au electrode. Electrochemical results showed that the PW12O403-/CHIT-graphene/cysteamine/Au electrode exhibited good electrochemical behaviors and electrocatalytic performance toward the reduction of NO2-. Electrocatalytic performance can be ascribed to large specific surface area and good conductivity of the CHIT-graphene nanocomposites and good electrocatalytic activity of PW12O403-. The sensor showed quick amperometric response, low detection limit, wide linear range, high sensitivity, high stability, and good reproducibility. Analytical performance suggests that it is possible to be a potential candidate for routine NO2- analysis.

MOFs-derived micro/nanostructures have important potential applications. In this review, we describe the use of MOFs as templates in the synthesis of metal/metal oxide micro/nanostructures and composite materials. The applications of the derived materials are also reviewed.

This article highlights recent advances in the controlled self-assembly of nanoparticles to produce dimeric nanoparticle structures. The relevance of this emergent field is discussed in terms of recent applications in plasmonics and chemical catalysis. The concept of bond-valence applied to nanoparticles will be discussed, emphasizing some general approaches that have been successfully used to build these structures. Further, the asymmetric functionalization of nanoparticles surfaces as a path to drive selective aggregation, the use of biomolecules to self-assemble nanoparticles into dimers in solution, and the confinement of aggregates in small cavities are discussed.

A novel nonenzymatic hydrogen peroxide (H2O2) sensor was simply prepared by depositing Pt nanoparticles (Pt NPs) onto Ni foam using UV-irradiation. Scanning electron microscopy was applied to characterize the changes of morphologies with UV-irradiation time. Energy dispersive spectroscopy confirmed that the Pt NP-Ni foam was mainly composed of Pt and Ni. The Pt NP-Ni foam electrode shared the unique advantages of Pt NPs (such as the good electrocatalytic activity) and Ni foam (such as the high electric conductivity, large surface area and high porosity). Its application in H2O2 detection, surprisingly, showed the high sensitivity and low detection limit. The linear range was from 0.005 to 0.85 mM. The sensitivity was 829 mA cm(-2) mM(-1) and the detection limit was 0.3 mM (S/N = 3). The H2O2 sensor also showed long-term stability. Therefore, the sensor is more suitable for the detection of H2O2 concentration.

A novel nonenzymatic glucose sensor was constructed based on anthill-like Cu@carbon nanocomposites which were derived from a Cu-based metal organic framework by a simple thermolysis method. The final nanocomposites were characterized by scanning electron microscopy, thermogravimetric analysis, X-ray powder diffraction and electrochemical techniques. The results showed that the derived nanocomposites maintained the morphology of the original materials upon thermolysis, while the produced Cu nanoclusters were embedded in three-dimensional carbon frameworks and presented an anthill-like structure. Since the final products gave a sufficiently large specific surface area, good catalytic activity towards the oxidation of glucose and appropriate pores for electrolyte transfer, the resultant glucose sensor based on the anthill-like Cu@carbon nanocomposites showed a wide linear range of 0.2-8.0 mM and a low detection limit of 29.8 mu M. The low cost, simple preparation and good catalytic activity of anthill-like Cu@carbon nanocomposites render them promising candidates as electrode materials for the construction of novel nonenzymatic sensors.

A simple and industrially scalable approach to prepare porous carbon (PC) with high surface areas as well as abundant nitrogen element as anode supporting materials for lithium-ion batteries (LIBs) was developed. Herein, the N-doped PC was prepared by carbonizing crawfish shell, which is a kind of food waste with abundant marine chitin as well as a naturally porous structure. The porous structure can be kept to form the N-doped PC in the pyrolysis process. The N-doped PC-Co3O4 nanocomposites were synthesized by loading Co3O4 on the N-doped PC as anode materials for LIBs. The resulting N-doped PC-Co3O4 nanocomposites release an initial discharge of 1223 mA h g(-1) at a current density of 100 mA g(-1) and still maintain a high reversible capacity of 1060 mA h g(-1) after 100 cycles, which is higher than that of individual N-doped PC or Co3O4. Particularly, the N-doped PC-Co3O4 nanocomposites can be prepared in a large yield with a low cost because the N-doped PC is derived from abundant natural waste resources, which makes it a promising anode material for LIBs.

A novel nonenzymatic glucose sensor was developed by electrodepositing dendritic copper-cobalt nanostructures (Cu-Co NSs) on glassy carbon electrode (GCE) which was modified by reduced grapheme oxide-chitosan (RGO-CHIT) nanocomposites. The electrochemical behaviors and electrocatalytic performances of the sensor towards oxidation of glucose were evaluated by cyclic voltammograms, chronoamperometry and amperometric method. Compared to sensors based on monometal Cu or Co NSs, the sensor based on bimetal Cu-Co NSs exhibits good electrocatalytic activity towards oxidation of glucose. The effects of electrodeposition time and the ratio of Cu2+ and Co2+ in an electrodeposition solution on the electrocatalytic performance of the Cu-Co NSs sensor were explored in detail. The best catalytic activity towards oxidation of glucose can be achieved under an optimized condition: electrodepositing time of 2600 s and the Cu2+/Co2+ molar ratio of 2:1. The catalytic current density is linear to the glucose concentration in the range of 0.015-6.95 mM (r = 0.9947) with a sensitivity of 1921 mu A cm(-2) mM(-1), and a detection limit of 10 mu M. The good catalytic activity, high sensitivity and good stability indicate that the newly developed sensor based on the dendritic Cu-Co NSs/RGO-CHIT/GCE is a promising sensor for application in real samples. (C) 2014 Elsevier B.V. All rights reserved.

The use of single molecules in electronics represents the next limit of miniaturisation of electronic devices, which would enable us to continue the trend of aggressive downscaling of silicon-based electronic devices. More significantly, the fabrication, understanding and control of fully functional circuits at the single-molecule level could also open up the possibility of using molecules as devices with novel, not-foreseen functionalities beyond complementary metal-oxide semiconductor technology (CMOS). This review aims at highlighting the chemical design and synthesis of single molecule devices as well as their electrical and structural characterization, including a historical overview and the developments during the last 5 years. We discuss experimental techniques for fabrication of single-molecule junctions, the potential application of single-molecule junctions as molecular switches, and general physical phenomena in single-molecule electronic devices.

Under 980 nm excitation, enhanced ultraviolet (UV) upconversion (UC) emissions at 242.4 nm, 276.1 nm, 289.7 nm, 296.4 nm, 303.6 nm, 357.7 nm and 387.8 nm of Ho3+ ions were observed in beta-NaYF4:20%Yb3+, 1.5%Ho3+ microcrystals (MC) which were synthesized through a hydrothermal method. The results indicated that these UV emissions came from five- and four-photon UC processes. Dynamical analysis on Ho3+ excited states suggests that, for excited Ho3+ ions, the higher the energy level is, the shorter the lifetime is.

Hierarchical Cu-Co-Ni nanostructures (Cu-Co-Ni NSs) attached to carbon nanofibers (CNFs) modified glassy carbon electrode (GCE) was prepared by electrodeposition. Scanning electron microscopy results indicated that many hierarchical Cu-Co-Ni NSs were formed and uniformly dispersed on the CNFs/GCE surface. The electrochemical behavior and electrocatalytic performance of the Cu-Co-Ni NSs/CNFs/GCE towards the oxidation of glucose were evaluated by cyclic voltammograms, chronoamperometry and amperometric methods. The results revealed that Cu-Co-Ni NSs/CNFs/GCE has a good electrocatalytic activity for glucose oxidation and could be used as a nonenzymatic glucose sensor. The sensor showed an acceptable linear range from 0.01 to 4.30 mM with a sensitivity of 104.68 mu A mM cm(-2), and a detection limit of 3.05 mM (S/N = 3). The good catalytic activity, high sensitivity, good selectivity and stability rendered the Cu-Co-Ni NSs/CNFs/GCE to be a promising electrode for constructing a nonenzymatic glucose sensor.

Nickel-cobalt nanostructures (Ni-Co NSs) electrodeposited on reduced graphene oxide (RGO)-modified glassy carbon electrode (GCE) was prepared and used for highly sensitive glucose detection. RGO nanosheets were firstly assembled onto GCE surface by pi-pi interaction and then Ni-Co NSs were constructed on RGO/GCE by dynamic potential scan. The electrochemical and electrocatalytic behaviors of the Ni-Co NSs/RGO/GCE toward glucose oxidation were evaluated by cyclic voltammograms, chronoamperometry and amperometric method. The effects of some factors related to the fabrication of Ni-Co NSs/RGO/GCE, such as potential scan number and the molar ratio of Ni2+/Co2+ in a solution, on the catalytic performance of the Ni-Co NSs/RGO/GCE were also explored. The results showed that the Ni-Co NSs/RGO/GCE exhibited the best catalytic activity at the potential scan number of 20 and the Ni2+/Co2+ molar ratio of 1:1. The glucose concentration in the range of 10 mu M to 2.65 mM linearly depended on the catalytic current (r = 0.9967, n=17). The sensitivity was 1773.61 mu A cm(-2) mM(-1), and the detection limit was 3.79 mu M (S/N = 3). This high catalytic activity, good sensitivity and stability of the Ni-Co NSs/RGO/GCE sensor opened up a new kind of hybrid materials in electrochemical detection of glucose. (C) 2013 Elsevier Ltd. All rights reserved.

Detection of H2O2 is very important in biological analysis, clinical diagnosis, food industry, etc. This work presents an electrochemical approach for the detection of H2O2 based on Prussian blue (PB) nanocubes-nitrobenzene-reduced graphene oxide (RGO) nanocomposites (PB nanocubes-nitrobenzene-RGO). The hybrid nanocomposites were constructed by growing PB nanocubes onto the nitrobenzene-RGO composites which were prepared by spontaneous grafting nitrophenyl groups to the basal carbon atoms of RGO based on chemical bonding. The obtained PB nanocubes-nitrobenzene-RGO nanocomposites were characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The formation mechanism of PB nanocubes-nitrobenzene-RGO nanocomposites was investigated and discussed in detail. The PB nanocubes-nitrobenzene-RGO modified glassy carbon electrode shows good electrocatalysis toward the reduction of H2O2. The resulted H2O2 biosensor exhibited a rapid response of 2 s, a low detection limit of 0.4 mu M, a wide linear range of 1.2 mu M to 15.25 mM and high sensitivity of 300.16 mu A cm(-2) mM(-1), as well as good stability, repeatability and selectivity. Further immobilizing glucose oxidase on the PB nanocubes-nitrobenzene-RGO nanocomposites/GCE, an amperometric glucose biosensor was achieved by monitoring the generated H2O2 under a relatively negative potential. The sensors might be used as a promising one for practical application. (C) 2013 Elsevier Ltd. All rights reserved.

Gold nanoparticles (NPs) of various shapes were synthesized by a one-step method at ambient temperature in the presence of NaCl. 2-mercaptosuccinic acid (MSA) was used as both reducing agent and stabilizing agent. The shapes of gold NPs were controllable by simply tuning S/Au ratio (S is from MSA molecule, and S/Au ratio is controlled by tuning the volume of added MSA solution), and triangle, polygonal and spherical nanoparticles were obtained. This result suggested a new way to consider the effects of MSA on the growth of nanoparticles, which showed that MSA is a strong capping agent and facilitates more uniform growth of nanoparticles in every dimension. And other important factors on nanoparticles growth including NaCl and temperature were discussed. Furthermore, a typical probe molecule, 4-aminothiophenol (4-ATP) was used to test the surface-enhanced Raman scattering (SERS) activity of these gold NPs and the results indicated good Raman activity on these substrates. And the enhancement factor (EF) at 1078 cm (1) (a(1)) was estimated to be as large as 6.3 x 10(4) and 5.5 x 10(4) for triangular plates and truncated particles, respectively.

Better understanding of the interaction between nanoparticles (NPs) and protein is the basis for biological and biomedical applications of NPs. Water-soluble fluorescent CdS NPs have been widely used in the biological and biomedical fields and the study on effect of CdS NPs size on conformation and enzymatic activity of protein might be very important in its application. In this work, the interaction of CdS NPs with different size with type II restriction endonuclease (EcoRI) were investigated by atomic force microscopy, transmission electron microscopy, UV-vis spectroscopy, fluorescence quenching method, CD spectra, laser scanning confocal microscopy and gel electrophoresis. It was found that the equilibrium constant (kD) as well as the cooperativity degree of CdS NPs-EcoRI binding (Hill constant, n) strongly depended on the CdS NPs size. The different curvature of CdS NPs surface could result in different changes of EcoRI conformation. The gel electrophoresis indicated that the decrease in α-helix content more or less affected the activity of EcoRI.

A low-cost and effective method to fabricate hexagonally patterned urchin-like ZnO nanowire arrays was demonstrated.The ordered monolayer of polystyrene(PS) spheres is obtained by self-assembly,and the monolayer is used as a template to grow ZnO nanowires with complex hierarchical structures via hydrothermal method.The urchin-like ZnO nanowire arrays are composed of PS sphere and ZnO nanowires.The nanowires have uniform diameter,and the length of the nanowires can be controlled by the growth time.This method provides a promising way to fabricate ZnO one-dimensional nanostructures for applications as sensor arrays,solar cells and photocatalysis.

We reported a simple method to synthesize ZnO–Au nanocomposites (hybrid A) by combining hydrothermal and electric beam evaporation deposition method. It was found that Au deposition time takes an important role in the generation of Au nanoparticles. Changing Au deposition time makes the thickness of Au formed on ZnO nanorods increase from 10nm to 70nm. On the other hand, white-emitting ZnO–Au nanocomposites (hybrid B) were obtained after treating hybrid A with HCl solution. Thanks to the covering of Au film and acid etching, it induces many defects on the surface of ZnO NRs, and largely enhances the visible emission of surviving ZnO and finally generates white emission on Au mesocrystals (hybrid B). Both of the ZnO–Au hybrids (A and B) can be applied as substrates in surface-enhanced Raman scattering (SERS) measurement. A typical probe molecule, 4-ATP was used to test the SERS activity of the ZnO–Au composites and the results indicated good Raman activity on the substrates.

用一种低成本的方法制备出了树形结构Si/ZnO纳米线阵列.首先在室温条件下用金属辅助化学腐蚀法在Si(100)衬底上制备了Si纳米线阵列,Si纳米线的直径尺寸及分布都很均匀,通过改变腐蚀时间,能够得到高度不同的Si纳米线阵列.利用磁控溅射在Si纳米线表面制备一层ZnO薄膜,然后利用水热法在Si纳米线阵列上生长了ZnO纳米线.通过扫描电子显微镜(SEM)、能谱分析仪(EDS)和光致发光(PL)测试对样品进行了表征.通过这种方法制备的Si/ZnO复合结构在太阳能电池、光催化等领域有潜在应用价值.

ZnO nanowire arrays with controlled diameter,density and orientation were prepared on the ZnO film coated substrates via hydrothermal method.The ZnO film were fabricated by atomic layer deposition(ALD) method and annealed at different temperatures.The annealing temperature has strong influences on the grain size,crystalline structure and defect property of the ZnO film.The diameter,density and orientation of ZnO nanowires depended on the features of the ZnO film.Field-emission scanning electron microscopy(SEM),X-ray diffraction(XRD) and photoluminescence(PL) were applied to analyze the ZnO film and ZnO nanowire arrays.The as-prepared vertical aligned ZnO nanowires are highly suitable for use in nanodevices,such as light-emitting diodes and solar cells.