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Continuous-flow nanocatalysis based on metal nanoparticle catalyst-anchored flow reactors has recently provided an excellent platform for effective chemical manufacturing. However, there has been limited progress in porous structure design and recycling systems for metal nanoparticle-anchored flow reactors to create more efficient and sustainable catalytic processes. In this study, traditional paper is used for a highly efficient, recyclable, and even renewable flow reactor by tailoring the ultrastructures of wood pulp. The 'paper reactor' offers hierarchically interconnected micro- and nanoscale pores, which can act as convective-flow and rapid-diffusion channels, respectively, for efficient access of reactants to metal nanoparticle catalysts. In continuous-flow, aqueous, room-temperature catalytic reduction of 4-nitrophenol to 4-aminophenol, a gold nanoparticle (AuNP)-anchored paper reactor with hierarchical micro/nanopores provided higher reaction efficiency than state-of-the-art AuNP-anchored flow reactors. Inspired by traditional paper materials, successful recycling and renewal of AuNP-anchored paper reactors were also demonstrated while high reaction efficiency was maintained. [ABSTRACT FROM AUTHOR]

We report on random lasing from polymer films containing Rh6G laser dye and gold nanoparticles (AuNPs). Different sizes of AuNP, varying from 10 to 150 nm, were used in the different films, but all had the same mass concentration of gold. We found a strong dependence of the random lasing characteristics (threshold for lasing, the emission intensity, and the spectral narrowing) on the size of the AuNP. In particular, we show that the emission intensity and threshold for lasing versus the NP size qualitatively agree with the prediction of the Mie‐type calculation that considers both the scattering cross section and the absorption of the NP. The experimental spectral narrowing versus the pumping energy is in qualitative agreement with calculations based on diffusion equations (which include appropriate scattering and absorbing terms). This suggests that photon scattering, as enhanced by surface plasmons (SPs) originating on the AuNP, is the dominant underlying mechanism for random lasing of our polymers. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

N‐Heterocyclic carbenes (NHCs) have drawn considerable interest in the field of nanomaterials chemistry as highly stabilizing ligands enabling the formation of strong and covalent carbon–metal bonds. Applied to gold nanoparticles synthesis, the most common strategy consists of the reduction of a preformed NHC‐AuI complex with a large excess of a reducing agent that makes the particle size difficult to control. In this paper, we report the straightforward synthesis of NHC‐coated gold nanoparticles (NHC‐AuNPs) by treating a commercially available gold(I) precursor with an easy‐to‐synthesize NHC‐BH3 reagent. The latter acts as both the reducing agent and the source of surface ligands operating under mild conditions. Mechanistic studies including NMR spectroscopy and mass spectrometry demonstrate that the reduction of gold(I) generates NHC‐BH2Cl as a by‐product. This strategy gives efficient control over the nucleation and growth of gold particles by varying the NHC‐borane/gold(I) ratio, allowing unparalleled particle size variation over the range of 4.9±0.9 to 10.0±2.7 nm. Our strategy also allows an unprecedented precise and controlled seeded growth of gold nanoparticles. In addition, the as‐prepared NHC‐AuNPs exhibit narrow size distributions without the need for extensive purification or size‐selectivity techniques, and are stable over months. [ABSTRACT FROM AUTHOR]

In this paper, the run of the decorating process of the active support, like CeO2, by the gold nanoparticles via deposition‐precipitation method has been studied. Two types of the Au/CeO2 systems with different mean particle size (but the same morphology) of the support have been investigated. It was noted that the decoration process proceeds easily only for large crystals with average size about 67 nm. Three hypotheses were tested in order to explain unsuccessful initial Au nanoparticles decoration of the cube‐like CeO2 crystals with average size about 14 nm as a support. The tests have shown that the ratio of the molar content of the chloroauric acid to the total surface area of the support (MAu/SCeO2) has a significant impact on the decorating process of CeO2 by nano‐Au. If the above ratio is too small, the thin layer of gold instead of the Au nanoparticles is formed on the support surface. In this paper, the calculations of the real surface area (from TEM/HRTEM data) were used to adjust the optimum the MAu/SCeO2 to obtain the Au/CeO2 system with the desired properties. [ABSTRACT FROM AUTHOR]

The influence of the size and oxidation state of Au nanoparticles (AuNPs) as electrocatalysts for the electro-oxidation of cellulose was studied. Carbon paper electrodes modified with AuNPs were used as the electrocatalysts for the electro-oxidation of cellulose dissolved in 1.3 m NaOH. The size and oxidation state of the AuNPs were determined by using SEM, TEM, and X-ray photoelectron spectroscopy. Both the size and the oxidation state of the AuNPs were found to influence the electrocatalytic properties of the electrode, as studied by using cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The carbon paper electrodes decorated with AuNPs (less than 25 nm) that consist of metallic Au gave rise to a significantly higher electrocatalytic activity than a bare polycrystalline Au electrode. [ABSTRACT FROM AUTHOR]

Biomass constitutes a renewable source for new chemical platforms. Among other processes the catalytic ones represent a green alternative when active and selective catalysts can be developed. In this paper, applications of gold and gold‐based catalysts have been reviewed in the field of the selective oxidations. Indeed, from the discovery of the peculiarity of gold as catalytic material, the liquid phase oxidations have been differently viewed. Three important biomass‐derived molecules, namely glucose, hydroxymethyl furfural (HMF) and glycerol have been considered as precursors for products of industrial interest where gold catalysts have played an important role. This review starts from the research on monometallic gold catalysts which have been explored initially and then look at gold as modifier of other metal catalyst. This latter field is still in evolution and probably needs to be look at in the future. Golden path: Applications of gold and gold‐based catalysts for selective liquid‐phase oxidation of biomass‐derived products have been reviewed. Three important molecules, namely glucose, hydroxymethyl furfural (HMF) and glycerol have been considered as precursors for products of industrial interest. [ABSTRACT FROM AUTHOR]

In this paper, we aimed at investigating the effect of the presence of small TiO2 crystallites over the transfer of hot electrons from Au nanoparticles (NPs) mediated by the surface plasmon resonance (SPR) excitation and its subsequent photocatalytic activities. To this end, we employed TiO2 colloidal spheres composed of TiO2 crystallites of 8.5 nm in size decorated with Au NPs (TiO2–Au) of 17 nm in size over the TiO2 surface as model materials. Moreover, the photocatalytic degradation of methylene blue (MB) under visible light excitation was employed as a target plasmonic transformation. We found that the plasmonic photocatalytic activity was significantly higher for the TiO2–Au hybrid relative to its individual Au NPs or TiO2 counterparts under excitation at 633 nm. These results could be explained based on the transfer of hot electrons generated upon the SPR excitation from Au NPs to the TiO2 conduction band in the TiO2–Au material, which will be recombined on the surface of TiO2 crystallites or at the interface between TiO2 crystallites, decreasing electrons density in Au NPs that lead to the formation of hydroxyl radicals that contribute and improve the photocatalytic degradation of MB. This mechanism was supported by the fact that the presence of TiO2 leads to a decrease in the p‐aminothiophenol to p,p′‐dimercaptoazobenzene SPR‐mediated oxidation in the TiO2–Au relative to Au NPs. We believe that the results reported herein suggest that TiO2–Au materials may represent attractive systems for designing plasmonic photocatalysts with improved performances towards a variety of transformations using solar/visible light as the energy input. TiO2–Au material presented improved plasmonic photocatalytic activity under visible light. TiO2 formed by small crystallites enhances plasmonic photocatalytic performance. This mechanism involving the transfer of SPR‐excited hot electrons from Au to TiO2 was further supported by probing the SPR‐mediated catalytic oxidation of p‐aminothiophenol (PATP) to p,p′‐dimercaptoazobenzene (DMAB). [ABSTRACT FROM AUTHOR]

So far, almost all electrochemistry theories are based on an assumption that the size of an electroactive molecule is negligible. However, this assumption will not be true if the size of an electroactive molecule is comparable to or smaller than the size of an electrode being used to study the electroactive molecule. In this paper, the electrochemical behaviors of ferrocenated gold nanoparticles have been studied using an electrode with a radius that is smaller than the radius of the particle. This allows for the observation of phenomena which cannot be explained by conventional electrochemical theories. Also, stochastic collision current, which cannot be observed on a macro- or microelectrode, can be directly observed. [ABSTRACT FROM AUTHOR]

Abstract: Mg(OH)2‐ and Mg(OH)2‐containing materials can provide excellent performance as supports for AuPd nanoparticles for the oxidation of glycerol in the absence of base, which is considered to be a result of additional basic sites on the surface of the support. However, its influence on the reaction solution is not generally discussed. In this paper, we examine the relationship between the basic Mg(OH)2 support and AuPd nanoparticles in detail using four types of catalyst. For these reactions, the physical interaction between Mg(OH)2 and AuPd was adjusted. It was found that the activity of the AuPd nanoparticles increased with the amount of Mg(OH)2 added under base‐free conditions, regardless of its interaction with the noble metals. In order to investigate how Mg(OH)2 affected the glycerol oxidation, detailed information about the performance of AuPd/Mg(OH)2, physically mixed (AuPd/C+Mg(OH)2) and (AuPd/C+NaHCO3) was obtained and compared. Furthermore, NaOH and Mg(OH)2 were added during the reaction using AuPd/C. All these results indicate that the distinctive and outstanding performance of Mg(OH)2 supported catalysts in base‐free condition is in fact directly related to its ability to affect the pH during the reaction and as such, assists with the initial activation of the primary alcohol, which is considered to be the rate determining step in the reaction. [ABSTRACT FROM AUTHOR]

During the last decade, nanotechnology has attained a significant place among the scientific community for the biosynthesis of plant‐based nanoparticles owing to its effective, safe, and eco‐friendly nature. Hence, keeping in view the significance of nanotechnology, the current study was conducted to develop, characterize (UV–visible spectroscopy, scanning electron microscopy, Fourier‐transform infrared spectroscopy, and energy‐dispersive X‐ray spectroscopy), and assess the antimicrobial (antibacterial and antifungal) properties of Peganum harmala L. Extract‐based Gold (Au) and Silver (Ag) nanoparticles (NPs). Characteristic absorption peaks at 420 and 540 nm revealed the formation of AgNPs and AuNPs, respectively. SEM images revealed that both silver and gold nanoparticles were oval and spherical with average size ranging from 42 to 72 and 12.6 to 35.7 nm, respectively. Similarly, FT‐IR spectra revealed that the functional groups such as hydroxyl, carboxyl, and polyphenolic groups of biomolecules present in the extract are possibly responsible for reducing metallic ions and the formation of nanoparticles. Likewise, the EDX analysis confirmed the presence of silver and gold in synthesized NPs. Furthermore, the AgNPs and AuNPs showed good antibacterial and antifungal activities. The maximum antibacterial and antifungal activity was noticed for P. harmala extract against Pseudomonas aeroginosa (21 mm) and Candida albicon (18 mm), respectively. Whereas, the maximum antibacterial and antifungal activities of synthesized AgNPs were observed against Salmonella typhi (25 mm) and Penicillium notatum (36 mm), respectively. Moreover, in the case of AuNPs, the highest antibacterial and antifungal activity of synthesized AuNPs was noticed against Escherichia coli (25 mm) and C. albicon (31 mm), respectively. Findings of this study revealed that P. harmala extract and biosynthesized NPs (silver and gold) possessed significant antibacterial and antifungal properties against different bacterial (Bacillus subtilis, Staphylococcus aureus, E. coli, P. aeroginosa, and S. typhi) and fungal (C. albicans, Aspergillus Niger, and P. notatum) strains. Further studies must be carried out to assess the probable mechanism of action associated with these antimicrobial properties. [ABSTRACT FROM AUTHOR]

The azidation of glutathione (GSH)‐functionalized ultrasmall gold nanoparticles (2 nm) by the azide transfer reagent imidazole‐1‐sulfonyl azide hydrogen sulfate leads to azide‐terminated nanoparticles with high yield. A subsequent copper‐catalyzed azide‐alkyne cycloaddition (CuAAC), i. e. a click reaction, leads to covalently functionalized nanoparticles. This was demonstrated with two alkyne‐functionalized dyes, i. e. FAM‐alkyne and AlexaFluor‐647‐alkyne, that were covalently coupled to the nanoparticles. The integrity of the glutathione ligand and the successful surface azidation were demonstrated by one‐dimensional and two‐dimensional NMR spectroscopy. The surface composition of the nanoparticles was determined by quantitative NMR spectroscopy and UV/vis spectroscopy. Each nanoparticle carries 125 glutathione molecules of which 118 were substituted by an azide group. After dye conjugation, either 6 FAM molecules or 11 AlexaFluor‐647 molecules were present on each nanoparticle, respectively. The dye‐clicked nanoparticles were highly fluorescent due to the absence of surface plasmon resonance. The post‐functionalization of GSH avoids a chemical reaction of a functional ligand during the reduction reaction, gives a high yield (up to 50 mg nanoparticles per batch), is based on water as solvent, and is applicable for metallic nanoparticles in general. [ABSTRACT FROM AUTHOR]

Nicotinamide adenine dinucleotide NAD(P)H is a prolific cofactor in oxidoreductases biochemistry, but its high cost and the stoichiometric amounts motivates significant research for establishing efficient solutions for regenerating NAD(P)H from NAD(P)+. This study presents nanoparticles of gold/layered double hydroxides (AuNPs/LDH) as nanoplatforms with highly efficient photocatalytic response for solar‐light promoted NADH regeneration. The novel photocatalysts are obtained via self‐assembling of ZnAlLDH and AuNPs by using the manifestation of the "structural memory" of the anionic clay in gold salt solution. The chemical composition, structural, optical and nanotextural features of AuNPs/LDH have been assessed by transmission electron microscopy (TEM), energy dispersive X‐Ray Spectroscopy (EDX), powder X‐ray diffraction (XRD), and UV‐Vis Spectroscopy (UV‐Vis). It was found that, at pH 8 and in the presence of flavin mononucleotide (FMN) as a mediator and using water as an electron donor, the regeneration the NADH under solar light is defined by a rate of 20.5 μM/h. Furthermore, the regenerated NADH cofactor is tested in presence of Horseradish Peroxidase (HRP) enzyme to promote the hydrogen peroxide reduction. [ABSTRACT FROM AUTHOR]

The calculated Au38 cluster is represented in the middle of the cover picture, coated by the N ‐ heterocyclic carbenes (NHCs) presented in the paper. The falling binary code “01” illustrates that the Au38 clusters are issued from DFT calculations. Molecular bis(NHC) gold complexes obtained from the functionalization of the particles are represented around the cluster. An experimental 1H NMR solid ‐ state spectrum is shown in the lower part of the cover to remind the reader that the study combines experimental and computational approaches. More information can be found in the Full Paper by F. Tielens, F. Remacle, S. Richeter et al. on page 10446 ff. [ABSTRACT FROM AUTHOR]

Dynamic nanoparticle assembly represents an important platform for the creation of functional materials with stimuli‐responsive properties. In this work, we show that small Au nanoparticles (ca. 5 nm) with mixed surface ligands (citrates and tannic acid) may be assembled into quasi‐sphere‐like superstructures (ca. 50 nm) induced by the presence of ferric ions. The spontaneous self‐limiting assembly is enabled by the localized metal‐phenolic interactions as a result of the possible phase separation of citrates and tannic acid on the surface of Au nanoparticles, restricting the growth of ionic cross‐linking network. The disassembly may be further achieved by adding ethylenediaminetetraacetic acid as a stronger chelation ligand for ferric ions, allowing the reversible assembly and disassembly of Au nanoparticles. Our results provide new insights into the design of dynamic plasmonic assemblies by manipulating the nature of surface ligands. [ABSTRACT FROM AUTHOR]

Understanding how the spatial ordering of liquid crystalline nanoparticles can be controlled by different factors is of great importance in the further development of their photonic applications. In this paper, we report a new key parameter to control the mesogenic behavior of gold nanoparticles modified by rodlike thiols. An efficient method to control the spatial arrangement of hybrid nanoparticles in a condensed state is developed by changing the composition of the mesogenic grafting layer on the surface of the nanoparticles. The composition can be tuned by different conditions of the ligand exchange reaction. The thermal and optical behavior of the mesogenic and promesogenic ligands were investigated by using differential scanning calorimetry (DSC) and hot-stage polarized optical microscopy. The chemical structure of the synthesized hybrid nanoparticles was characterized by 1H NMR spectroscopy, thermogravimetric analysis (TGA), XPS, and elemental analysis, whereas the superstructures were examined by small-angle X-ray diffraction (SAXSRD) analysis. Structural studies showed that the organic sublayer made of mesogenic ligands is denser with an increasing the average ligand number, thereby separating the nanoparticles in the liquid crystalline phases, which changes the parameters of these phases. [ABSTRACT FROM AUTHOR]

The Cover shows an industrial landscape, where Au nanoparticles are used as catalysts for oxidation reactions.In their Full Paper, L. M. D. R. de Sousa Martins et al. demonstrate an efficient single‐pot oxidative functionalization of cyclohexane and benzyl and methylbenzyl alcohols under mild conditions with high selectivity, catalyzed by reusable Au nanoparticles on Al2O3, Fe2O3, ZnO, and TiO2. Au nanoparticles on Fe2O3 led to an unusual almost exclusive formation of cyclohexanol by control of reaction time, but Au nanoparticles on TiO2 had a remarkable catalytic effect on acetophenone yield. [ABSTRACT FROM AUTHOR]

Purpose: Noble metal nanoparticles have found several medical applications in the areas of radiation detection; x-ray contrast agents and cancer radiation therapy. Based on computational methods, many papers have reported the nanoparticle effect on the dose deposition in the surrounding medium. Here the authors report experimental results on how silver and gold nanoparticles affect the dose deposition in alanine dosimeters containing several concentrations of silver and gold nanoparticles, for five different beam energies, using electron spin resonance spectroscopy (ESR). Methods: The authors produced alanine dosimeters containing several mass percentage of silver and gold nanoparticles. Nanoparticle sizes were measured by dynamic light scattering and by transmission electron microscopy. The authors determined the dose enhancement factor (DEF) theoretically, using a widely accepted method, and experimentally, using ESR spectroscopy. Results: The DEF is governed by nanoparticle concentration, size, and position in the alanine matrix. Samples containing gold nanoparticles afford a DEF higher than 1.0, because gold nanoparticle size is homogeneous for all gold concentrations utilized. For samples containing silver particles, the silver mass percentage governs the nanoparticles size, which, in turns, modifies nanoparticle position in the alanine dosimeters. In this sense, DEF decreases for dosimeters containing large and segregated particles. The influence of nanoparticle size-position is more noticeable for dosimeters irradiated with higher beam energies, and dosimeters containing large and segregated particles become less sensitive than pure alanine (DEF < 1). Conclusions: ESR dosimetry gives the DEF in a medium containing metal nanoparticles, although particle concentration, size, and position are closely related in the system. Because this is also the case as in many real systems of materials containing inorganic nanoparticles, ESR is a valuable tool for investigating DEF. Moreover, these results alert to the importance of controlling the sizeposition of nanoparticles to enhance DEF. [ABSTRACT FROM AUTHOR]

Purpose: This paper reports a technique that enables the quantitative determination of the concentration of gold nanoparticles (GNPs) through the accurate detection of their fluorescence radiation in the diagnostic x-ray spectrum. Methods: Experimentally, x-ray fluorescence spectra of 1.9 and 15 nm GNP solutions are measured using an x-ray spectrometer, individually and within chicken breast tissue samples. An optimal combination of excitation and emission filters is determined to segregate the fluorescence spectra at 66.99 and 68.80 keV from the background scattering. A roadmap method is developed that subtracts the scattered radiation (acquired before the insertion of GNP solutions) from the signal radiation acquired after the GNP solutions are inserted. Results: The methods effectively minimize the background scattering in the spectrum measurements, showing linear relationships between GNP solutions from 0.1% to 10% weight concentration and from 0.1% to 1.0% weight concentration inside a chicken breast tissue sample. Conclusions: The investigation demonstrated the potential of imaging gold nanoparticles quantitatively in vivo for in-tissue studies, but future studies will be needed to investigate the ability to apply this method to clinical applications. [ABSTRACT FROM AUTHOR]

The image illustrates the operation mechanism of the photothermal activation of Ru/Au nanoparticles deposited on Siralox. Upon absorption of light by Au nanoparticles, the photon energy is thermalized, leading to the heating of smaller Ru nanoparticles located on the Au surface. This local heating serves to promote the selective methanation of CO2 by H2. For more information, see the Full Paper by H. García et al. on page 18436 ff. [ABSTRACT FROM AUTHOR]

Adipic acid (AA) is one of the highest volume chemicals in world use with a wide range of commercial applications. This paper demonstrates the possibility of producing significant proportions of AA by the selective oxidation of cyclohexane (CH) in one step using various supported gold-nanoparticle (AuNP) catalysts. The catalysts were characterized by ICP, BET, XRD, X-ray photoelectron microscopy, and TEM. The catalytic activity tests were carried out in the liquid phase using autoclaves in the temperature range of 100-170 °C at 10 bar. A CH conversion of over 25 %, with 26% selectivity of AA and 70% selectivity of KA oil (cyclohexanone+cyclohexanol), was achieved over a nano-gold/TiO2 (anatase) catalyst. The superior performance of this catalyst is attributed to the smaller size of AuNPs, which has an average particle size of 2 nm. Good correlation between activity and Au particle size could be achieved. Overall, the particle size of the AuNPs showed a strong influence on catalytic performance. [ABSTRACT FROM AUTHOR]

This paper describes a surface-enhanced Raman scattering (SERS) systematic investigation regarding the functionalization of gold (Au) and silver (Ag) nanoparticles with diphenyl dichalcogenides, i.e. diphenyl disulfide, diphenyl diselenide, and diphenyl ditelluride. Our results showed that, in all cases, functionalization took place with the cleavage of the chalcogen-chalcogen bond on the surface of the metal. According to our density functional theory calculations, the molecules assumed a tilted orientation with respect to the metal surface for both Au and Ag, in which the angle of the phenyl ring relative to the metallic surface decreased as the mass of the chalcogen atom increased. The detected differences in the ordinary Raman and SERS spectra were assigned to the distinct stretching frequencies of the carbon-chalcogen bond and its relative contribution to the ring vibrational modes. In addition, the SERS spectra showed that there was no significant interaction between the phenyl ring and the surface, in agreement with the tilted orientation observed from our density functional theory calculations. The results described herein indicate that diphenyl dichalcogenides can be successfully employed as starting materials for the functionalization of Au nanoparticles with organosulfur, organoselenium, and organotellurium compounds. On the other hand, diphenyl disulfide and diphenyl diselenide could be employed for the functionalization of Ag nanoparticles, while the partial oxidation of the organotellurium unit could be detected on the Ag surface. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Graphene oxide nanoribbons (GONRs), obtained from the oxidative unzipping of carbon nanotubes, have been investigated as building blocks towards reaching active platforms in surface-enhanced Raman scattering (SERS). The complete development of carbon nanomaterials is strongly related to the exploitation of their chemical versatility, so this work is focused on the positive effect that a specific chemical functionalization provides to the SERS effect when gold nanoparticles are used. The covalent derivatization of GONRs with terminal thiol groups boosts their interaction with different types of gold nanoparticles (namely, ‘naked’ or citrate-stabilized), and the resulting two-dimensional aggregates show an intense enhancement of the Raman scattering from the carbon nanostructures because of their two-dimensional extended aggregation pattern. The SERS effect has been corroborated by theoretical calculations and a conceptual proof of SERS-based sensing. [ABSTRACT FROM AUTHOR]

Background: The rapid detection and efficient properties of surface‐enhanced Raman scattering (SERS) have been widely exploited in food safety. Purpose: In this study, the SERS impact of cysteine‐functionalized gold core‐silver shell bimetallic nanoparticle (Au@Ag@CysNPs) substrates with different pH treatments on pesticide compounds was examined. Results: The pH‐dependent SERS impact of Au@Ag@CysNPs on detecting pesticide compounds exhibited different enhancements over the pH range of 2–11 and exited the highest enhancement at a pH of 5 for thiabendazole and thiram pesticides. The prepared Au@Ag@CysNPs were further utilized in SERS‐based rapid detection of pesticides on apple peels by directly dropping Au@Ag@CysNPs on the surface of the samples, where the target molecules could be identified without elution or extraction. These findings revealed that this Au@Ag@CysNPs substrate exhibited excellent SERS performances for pesticide compounds and good stability. With additional optimization, detection limits of 0.1 ng/cm2 for thiabendazole and thiram on apple peels were obtained. [ABSTRACT FROM AUTHOR]

Abstract: The localized surface plasmon resonance (LSPR) excitation in plasmonic nanoparticles can enhance or mediate chemical transformations. Increased reaction rates for several reactions have been reported due to this phenomenon; however, the fundamental understanding of mechanisms and factors that affect activities remains limited. Here, by investigating hydrogenation reactions as a model transformation and employing different reducing agents, H2 and NaBH4, which led to different hydrogenation reaction pathways, we observed that plasmonic excitation of Au nanoparticle catalysts can lead to negative effects over the activities. The underlying physical reason was explored using density functional theory calculations. We observed that positive versus negative effects on the plasmonic catalytic activity is reaction‐pathway dependent. These results shed important insights on our current understanding of plasmonic catalysis, demonstrating reaction pathways must be taken into account for the design of plasmonic nanocatalysts. [ABSTRACT FROM AUTHOR]

The cover picture shows puffball‐shaped, flavin‐functionalized, monolayer‐protected gold nanoparticles that efficiently catalyze aerobic transformations. In their Full Paper, Y. Imada, T. Naota and co‐workers describe the synthesis of PPh3‐protected gold clusters functionalized with cationic and neutral flavins, and their catalytic activities for the aerobic oxidation of sulfides and reduction of alkenes. Both the oxidation and reduction reactions proceed with high efficiency under atmospheric pressure in O2 or air and mild conditions. The advantages of the nanoparticle catalysts over conventional methods are discussed from synthetic and mechanistic viewpoints. The article highlighted by this cover can be found on p. 99 ff. of Issue 1, 2015. [ABSTRACT FROM AUTHOR]

Water‐soluble and air‐stable gold nanoparticles stabilized by a xyloside‐based ligand containing a pyridine ring‐functionalized 1,2,3‐triazole backbone were prepared in the presence of a reducing agent. During their preparation, UV‐vis and NMR spectroscopic techniques were used to study the interaction between the xyloside ligand and Au(III) ions. These AuNPs were characterized by UV‐vis spectroscopy, TEM and DLS and showed a small size (average diameter<10 nm determined by TEM). Their catalytic activity was tested in the reduction of 4‐nitrophenol (4‐NP) to 4‐aminophenol (4‐AP) in water. [ABSTRACT FROM AUTHOR]

The best activity of bimetallic AuPd nanoparticles for alcohol oxidation reaction is usually achieved by adjusting the Au/Pd molar ratio. Herein, alloy AuPd nanoparticles of ∼2.5–3.5 nm, ranging from Au‐rich to Pd‐rich compositions, were synthesized through a sol‐immobilization method. A calcination step under air conditions caused an increase in size up to 5.5 nm, but also driven the segregation of Pd to the surface, which generated an Au rich core with Pd on the shell. At high Pd content, the shell structure is formed by PdO. The catalytic activity of Pd‐rich samples (1 : 1, 1 : 2 and 1 : 4 Au : Pd) for benzyl alcohol oxidation increased ∼4‐fold after calcination. Upon reduction with H2, surface PdO motifs are reduced to Pd that did not dissolve back into the AuPd alloy core, maintaining the metallic Pd shell. The catalytic activity decreased. Therefore, restructuring alloyed AuPd nanoparticles into core‐shell like structures with PdO in the shell is beneficial to the catalytic activity, but reduction of PdO layer was detrimental. These results provide new insights on the optimization of AuPd catalysts, considering not only the Au/Pd molar ratio, but also the importance of PdO, which was not anticipated in the previous literature. [ABSTRACT FROM AUTHOR]

The cover picture shows the growth mechanism of Cu2O/noble‐metal nanocomposites and the application of these nanocomposites as surface‐enhanced Raman scattering (SERS) substrates, as reported by Z. Wang and co‐workers in their Full Paper on page 684 ff. They aim to synthesize SERS substrates with high sensitivity and good reproducibility for the detection of food contaminants. [ABSTRACT FROM AUTHOR]

Brown and gold The cover picture illustrates the concept of using gold nanoparticle‐decorated carbon nanotubes to directly electrochemically oxidize alginate—the principle, difficult‐to‐degrade component of brown macroalgae (as shown in the background of the cover picture). In their Full Paper on p. 135 ff., L. Q. Hoa, E. Tamiya et al. present analyses that suggest a reaction pathway similar to the chemical oxidation process by strong oxidants that results in oxidized alginate usable for cell and tissue engineering. This straightforward approach, in contrast to currently employed alginate‐metabolizing microbial approaches, can enhance the energy extraction efficiency of the whole biomass‐to‐energy conversion process through a fuel cell system without requiring any external energy, while simultaneously producing high‐value chemicals, paving the way for the future production of energy and feedstock materials from inedible biomass. [ABSTRACT FROM AUTHOR]

Embedding nanoparticles in a responsive polymer matrix is a formidable way to fabricate hybrid materials with predesigned properties and prospective applications in actuators, mechanically tunable optical elements, and electroclinic films. However, achieving chemical compatibility between nanoparticles and organic matter is not trivial and often results in disordered structures. Herein, it is shown that using nanoparticles as exclusive cross-linkers in the preparation of liquid-crystalline polymers can yield long-range-ordered liquid-crystalline elastomers with high loadings of well-dispersed nanoparticles, as confirmed by small-angle XRD measurements. Moreover, the strategy of incorporating NPs as cross-linking units does not result in disruption of mechanical properties of the polymer, and this phenomenon was explained by the means of all-atom molecular dynamics simulations. Such materials can exhibit switchable behavior under thermal stimulus with stability spanning over multiple heating/cooling cycles. The presented strategy has proven to be a promising approach for the preparation of new types of hybrid liquid-crystalline elastomers that can be of value for future photonic applications. [ABSTRACT FROM AUTHOR]

Silicon-based structures comprised of crystalline silicon substrates and active layers of mixed silicon and gold nanoparticles were fabricated and characterized. Several layer compositions were studied. The investigated structures demonstrate very large spectral sensitivity (more than 10 A W−1) in the wide spectral range (400-1000 nm). Such large sensitivity implies presence of photocurrent amplification. A model which involves dual mechanism of the photoresponse was proposed in order to explain the appearance of the photocurrent amplification in the investigated structures. Spectral sensitivity of the structure with composite layer of Si and Au nanoparticles on Si substrate (Au volume fraction is ∼50%) at reverse bias voltage of −0.4 V. [ABSTRACT FROM AUTHOR]

The correlation between the size of nanoparticles, the structure and shape of mesogenic ligands and the ensuing assembly behaviour is not really understood. Closer inspection shows very surprising features. Here, 2‐ and 4‐nm gold nanoparticles (NPs) were synthesized, and grafted with a forked ligand containing two rod‐like mesogens in its branches: one cholesterol, the other with azobenzene. The 4‐nm NPs also contained n‐hexylthiol as co‐ligand. They were found to form a FCC cubic superlattice, whereas the 2‐nm NPs form hexagonal HCP with weak birefringence, hence with partially oriented ligands. The structures were compared with those of related systems containing a range of different azobenzene‐to‐cholesterol ratios, all giving body‐centred tetragonal superlattices with various degrees of anisotropy. Geometric analysis is presented in terms of the asphericity of the NPs' surroundings, requirement for space‐filling and structural anisotropy. Some general rules are derived to help design the soft corona around the NPs in order to obtain superlattices with the desired structure and anisotropy. [ABSTRACT FROM AUTHOR]

New water ‐ soluble gold nanoparticles stabilized by a nitrogen ‐ rich poly(ethylene glycol) (PEG) ‐ tagged substrate, which displayed excellent activity as recyclable catalyst for the mild and selective reduction of nitroarenes in water, have been prepared and characterized. Moreover, their potential ability as refractive index sensors has been demonstrated. More information can be found in the Full Paper on page 2437 by Roser Pleixats et   al. (DOI: 10.1002/asia.201500290). [ABSTRACT FROM AUTHOR]

Gold particles supported on tin(IV) oxide (0.2 wt % Au/SnO2) were modified with copper and silver by the multistep photodeposition method. Absorption around λ=550 nm, attributed to surface plasmon resonance (SPR) of Au, gradually shifted to longer wavelengths on modification with Cu and finally reached λ=620 nm at 0.8 wt % Cu. On the other hand, the absorption shifted to shorter wavelength with increasing amount of Ag and reached λ=450 nm at 0.8 wt % Ag. These Cu- and Ag-modified 0.2 wt % Au/SnO2 materials (Cu-Au/SnO2 and Ag-Au/SnO2) and 1.0 wt % Au/SnO2 were used for mineralization of formic acid to carbon dioxide in aqueous suspension under irradiation with visible light from a xenon lamp and three kinds of light-emitting diodes with different wavelengths. The reaction rates for the mineralization of formic acid over these materials depend on the wavelength of light. Apparent quantum efficiencies of Cu-Au/SnO2, Au/SnO2, and Ag-Au/SnO2 reached 5.5 % at 625 nm, 5.8 % at 525 nm, and 5.1 % at 450 nm, respectively. These photocatalysts can also be used for selective oxidation of alcohols to corresponding carbonyl compounds in aqueous solution under visible-light irradiation. Broad responses to visible light in formic acid mineralization and selective alcohol oxidation were achieved when the three materials were used simultaneously. [ABSTRACT FROM AUTHOR]

The cover picture shows the TEM pictures of new gold nanoparticles confined in the ORMOSIL matrix of SiliaCat Au catalyst as background, with superimposed reaction scheme for the model oxidation of 1‐phenylethanol with hydrogen peroxide. In their Full Paper, L. M. Ilharco, M. Pagliaro and co‐workers explain why and how this new catalyst series is ideally suited for the practical utilization of sol‐gel encapsulated gold nanoparticles in a number of different reactions. The catalyst has a huge surface area and has been extensively characterized. The article highlighted by this cover can be found on p. 254 ff. of Issue 2, 2015. [ABSTRACT FROM AUTHOR]

Targeting amyloid-β (Aβ)-induced complex neurotoxicity has received considerable attention in the therapeutic and preventive treatment of Alzheimer's disease (AD). The complex pathogenesis of AD suggests that it requires comprehensive treatment, and drugs with multiple functions against AD are more desirable. Herein, AuNPs@POMD-pep (AuNPs: gold nanoparticles, POMD: polyoxometalate with Wells-Dawson structure, pep: peptide) were designed as a novel multifunctional Aβ inhibitor. AuNPs@POMD-pep shows synergistic effects in inhibiting Aβ aggregation, dissociating Aβ fibrils and decreasing Aβ-mediated peroxidase activity and Aβ-induced cytotoxicity. By taking advantage of AuNPs as vehicles that can cross the blood-brain barrier (BBB), AuNPs@POMD-pep can cross the BBB and thus overcome the drawbacks of small-molecule anti-AD drugs. Thus, this work provides new insights into the design and synthesis of inorganic nanoparticles as multifunctional therapeutic agents for treatment of AD. [ABSTRACT FROM AUTHOR]

Azafullerene (C59N) was functionalized using a Mannich-type reaction and then subsequently condensed with lipoic acid to yield dithiolane-modified C59N. In the following step, the extended dithiolane moiety from the C59N core was utilized to decorate the azafullerene sphere with gold nanoparticles (Au NPs). The latter were initially stabilized with dodecanothiol (DT ⋅Au) and then integrated on azafullerene through a ligand exchange reaction with the dithiolane-functionalized C59N to produce the C59N/DT ⋅Au nanohybrid. The nanohybrid was fully characterized by spectroscopy and microscopy, revealing the formation of spherical nanoparticles with a diameter in the range of 2-5 nm, as imaged by HR-TEM. In the electronic absorption spectrum of C59N/DT ⋅Au nanohybrid, the characteristic surface plasmon band (SPB) of Au NPs was observed, however, it was redshifted compared with that of DT ⋅Au. The redshift of the SPB is indicative of closer interparticle proximity of Au NPs, in accordance with the formation of aggregated NPs as observed by TEM, in C59N/DT ⋅Au nanohybrid. Excited-state interactions in C59N/DT ⋅Au were probed by photoluminescence assays. It was found that the weak emission of C59N at 819 nm was blueshifted by 14 nm in C59N/DT ⋅Au, but was stronger in intensity, thus suggesting energy transfer to C59N, within the organic-inorganic C59N/DT ⋅Au nanohybrid. Finally, with the aid of pump-probe measurements and transient absorption spectroscopy, the formation of the singlet excited state of C59N was identified. [ABSTRACT FROM AUTHOR]

A newly prepared [(ppy)2Ir(dcbpy)]+⋅PF6− (ppy: 2-phenylpyridyl; dcbpy: 4,4′-dicarboxy-2,2′-bipyridyl) and gold nanoparticle functionalized mesoporous silica nanoparticle (Au/Ir-MSN) is reported. Based on the binding between concanavalin A (Con A) and mannose, the novel nanoparticle was applied to an ultrasensitive electrochemiluminescence (ECL) in situ cytosensing strategy and the dynamic evaluation of cell-surface carbohydrate expression. The ECL activity of the presented Con A@Au/Ir-MSN nanoprobe was greatly enhanced by employing a functionalized nanoparticle and graphene nanomaterial with an increased surface area and simultaneously improved electron-transfer efficiency at the electrode interface. Under optimal conditions, the sandwich-type ECL cytosensor showed a linear response to K562 cells at concentrations ranging from 1.0×102 to 1.0×106 cells mL−1 and realized a low detection limit of a single cell. The proposed method could also be successfully used for monitoring the dynamic variation of carbohydrate expression in cancer cells in response to external stimulation by an inhibitor. [ABSTRACT FROM AUTHOR]

Anisotropic noble-metal structures are attracting increasing attention because of interesting size- and shape-dependent properties and have emerging applications in the fields of optics and catalysis. However, it remains a significant challenge to overcome chemical contributions and acquire molecular insight into the relationship between Raman enhancement and photocatalytic activity. This study gives visualized experimental evidence of the anisotropic spatial distribution of Raman signals and photocatalytic activity at the level of single nanometer-thin Au microtriangles and microhexagons. Theoretical simulations indicate an anisotropic spatial distribution and sharpness-dependent strength of the electric-field enhancement. Analysis by using statistical surface-enhanced Raman scattering (SERS) supports this view, that is, Raman enhancement is on the order of corner>edge>face for a single microplate, but SERS measurements at different depths of focus also imply a concentration-dependent feature of SERS signals, especially at the corners and edges. Similarly, the SERS signals of product molecules in plasmonic photocatalysis also exhibit asymmetrical strengths at different corners of the same microplate. However, by examining the variations in the relative intensities of the SERS peaks, the difference in the photocatalytic activities at the corners, edges, and faces has been successfully calculated and is highly consistent with electric-field simulations, thus indicating that an increased number of molecules adsorbed at specific sites does not necessarily lead to a higher conversion ratio in noble-metal photocatalysis. Our strategy weakens the assumed impact of plasmonic local heating and, to a certain extent, excludes the influence of concentration effects and chemical contributions in noble-metal photocatalysis, thus clearly profiling plasmon-related characteristics. This study also promises a new research direction to understand the enhancement mechanism of SERS-active structures. [ABSTRACT FROM AUTHOR]

The present article reports the preparation of Pd-Au alloy incorporated into NaY zeolites layer via simple immersion technique. Pd-Au particles were incorporated into zeolites cages via Co-impregnation or alternate impregnation of metal ions. Cyclic voltammetry was used to evaluate the state of the modified electrodes in alkaline media. Surface morphology as well as elemental composition of the modified layer were examined using Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). [ABSTRACT FROM AUTHOR]

The enzymeless glucose oxidation process readily occurs on nano-gold electrocatalyst at pH 7, but it is highly susceptible to poisoning (competitive binding), for example from protein or chloride. Is it shown here that gold nanoparticle catalyst can be protected against poisoning by a polymer of intrinsic microporosity (PIM-EA-TB with BET surface area 1027 m2 g−1). This PIM material when protonated, achieves a triple catalyst protection effect by (i) size selective repulsion of larger protein molecules (albumins) and (ii) membrane ion selection effects, and (iii) membrane ion activity effects. PIM materials allow 'environmental control' to be introduced in electrocatalytic processes. [ABSTRACT FROM AUTHOR]

Reactive ion etching was used to fabricate black-Si over the entire surface area of 4-inch Si wafers. After 20 min of the plasma treatment, surface reflection well below 2% was achieved over the 300-1000 nm spectral range. The spikes of the black-Si substrates were coated by gold, resulting in an island film for surface-enhanced Raman scattering (SERS) sensing. A detection limit of 1 × 10−6 M (at count rate > 102 s−1 . mW−1) was achieved for rhodamine 6G in aqueous solution when drop cast onto a ∼ 100-nm-thick Au coating. The sensitivity increases for thicker coatings. A mixed mobile-on-immobile platform for SERS sensing is introduced by using dog-bone Au nanoparticles on the Au/black-Si substrate. The SERS intensity shows a non-linear dependence on the solid angle (numerical aperture of excitation/collection optics) for a thick gold coating that exhibits a 10 times higher enhancement. This shows promise for augmented sensitivity in SERS applications. [ABSTRACT FROM AUTHOR]

Surface ‐ passivated SBA ‐ 15 ‐ supported gold nanoparticles that were nearly superhydrophobic, with a contact angle of 144°, were prepared by surface passivation based on a modified impregnation method, as reported by Jinsuo Gao et   al. in their Full paper on page   934   ff. In their study, which is featured on the Inside Cover, the authors found that the catalytic activity of these nanoparticles regarding the reduction of nitrobenzene was significantly increased (>14 times) when compared with non ‐ passivated SBA ‐ 15. Interestingly, the catalyst exhibited almost no catalytic activity for the more hydrophilic substrate 4 ‐ nitrophenol. Accordingly, such surface ‐ passivated catalysts may find use in the selective catalysis of hydrophobic substrates. [ABSTRACT FROM AUTHOR]

Selective oxidation The inside cover picture shows a mystique of TiO2‐supported Au nanoparticles as a photocatalyst for partial oxidations of organic substrates under sunlight irradiation and a CO2 atmosphere. In their Full Paper on p. 766 ff., Y. Ide et al. describe how the photocatalytic oxidation of aqueous phenol to hydroquinone on the catalyst under sunlight is modified to give a higher yield and selectivity if the reaction is conducted under a CO2 atmosphere. Au loading causes neither the visible light response nor the improved UV light‐induced charge separation efficiency of TiO2. A unique role of Au loading in the photocatalysis is proposed; Au nanoparticle loading drastically decreases the amount of the surface titanol, promoting the desorption of the product hydroquinone from the catalyst surface, especially if CO2 is present in the system. [ABSTRACT FROM AUTHOR]

Bimetallic Au–Pd nanoparticles were prepared in the functionalized ionic liquid [C2OHmim][NTf2] by the thermal decomposition of Pd(OAc)2 and Au(OAc)3. The Au atoms are mostly located in the NP core, leaving the Pd atoms ENriched at the surface. Moreover, the Pd atoms are electropositive, which leads to high activity in catalytic dehalogENation reactions. The activity of the heteronuclear nanoparticles may be attributed to charge transfer from Pd to Au and consequENtly to more efficiENt reductive elimination. For more details, see the Full Paper by N. Yan et   al. on page   1227   ff. [ABSTRACT FROM AUTHOR]

Au L3-edge X-ray absorption spectroscopic measurements were carried out over a series of mesoporous and microporous materials containing gold nanoparticles to investigate the effects of the host matrix and preparation methods on the properties of gold nanoparticles. The materials of structure type MCM-41, ZSM-5, SAPO-18 and LSX with varying framework composition containing low concentrations of gold nanoparticles were prepared and characterized. In these materials the size of the gold nanoparticles varied in the range ∼1 to 4 nm. A series of gold nanoparticles within different mesoporous and microporous materials have been investigated using X-ray absorption fine structure (XANES, EXAFS) and other techniques. Information such as atomic distances, bonding and neighbouring environment obtained from XAFS measurements was useful in elucidating the nature and structure of gold nanoparticles on these catalytic materials. The influence of the high-temperature (823, 1113, 1273 K) treatment on gold nanoparticles inside the mesoporous matrix was investigated using the XAFS technique. The XAFS and XANES results confirm various characteristics of gold nanoparticles in these materials suitable for catalysis, fabrication of nanodevices and other applications. [ABSTRACT FROM AUTHOR]

Whole-profile-fitting least-squares techniques are applied to simulated and experimental X-ray diffraction patterns of monatomic face-centred cubic (f.c.c.)-derived non-crystallographic nanoclusters to extra structure and size information. There main structure types have been considered (cuboctahedral. icosahedral and decahedral). Nonocluster structure models have been generated within an original mathematical approach so as to be independent of a specific material. For each structure type, a log-normal size distribution is assumed and a phenomenological function is introduced to model possible addition size related strain effects. The Debye function method (modified to increase computational efficiency) has been used to obtain the diffracted intensities of the nanocluster. Tests revealed the effectiveness of the method to recognize the structure types correctly and to estimate with good accuracy structure concentration and size distribution. Application to a thiol-passivated gold nonoparticle sample is presented. [ABSTRACT FROM AUTHOR]

Frontispiece: Selective Release of Doxorubicin from Cucurbit[8]uril Stabilized Gold Supra-Pyramid Host at pH of Small Intestine Keywords: anticancer drugs; cucurbituril; host-guest systems; nanoparticles; supra-pyramid EN anticancer drugs cucurbituril host-guest systems nanoparticles supra-pyramid 1 1 1 11/28/20 20201126 NES 201126 B Chemotherapeutic drug doxorubicin b is used in permutation with additional medicines to treat various types of cancer including Hodgkin's, non-Hodgkin's lymphoma and acute myeloid leukemia. Anticancer drugs, cucurbituril, host-guest systems, nanoparticles, supra-pyramid. [Extracted from the article]

Metal nanoparticles have generated great interest due to their excellent optical and chemical properties. The widely used chemical method for synthesising nanoparticles involves capping agents for colloidal stability. However, there are scarce reports on the application of metal nanoparticles synthesised without using capping agents. Hence, there is a need to develop pristine nanoparticles devoid of capping that can be used for translational research. Here, the authors developed a facile and rapid method for synthesising bare metal nanoparticles (platinum/silver/gold) that are chemically reactive and stable for a month upon storage. They synthesised bare metal nanoparticles of sub‐15 nm and characterised using standard techniques (UV–VIS‐NIR/DLS/zeta//TEM/XRD). They assessed the safety of the synthesised nanoparticles on the liver carcinoma cell line (HepG2). Bare gold and platinum nanoparticles were non‐toxic in comparison to bare silver nanoparticles. Bare metal nanoparticles were also checked for metal detection wherein antimony, mercury and chromium were detected using bare gold and silver nanoparticles. The spectroscopic shifts of the nanoparticles when bound to metals resulted in blue and red shifting of the plasmon band, indicating the sensing of metals. These results show that bare metal nanoparticles have the potential to emerge as a promising candidate for biomedical and sensing applications. [ABSTRACT FROM AUTHOR]