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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]

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]

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]

Gold nanoparticles (AuNPs) can be obtained from HAuCl4 by using poly(ethyleneimine) (PEI) as both reductant and stabilizing agent. However, the known affinity of PEI for different materials has not been exploited to coat them and turn their surface catalytic. We demonstrate that the irradiation of a solution of HAuCl4 and branched PEI 1800 (bPEI2K) with microwave (MW) yields PEI-stabilized AuNPs (MW-PEI@AuNPs) with an average size of 7.6 nm that are catalytically active in the reduction with NaBH4 of different nitroarenes functionalized with a variety of functional groups. Moreover, the as-prepared MW-PE@-AuNPs show affinity for different materials such as polystyrene (standard spectrophotometry disposal cuvettes), polypropylene (Falcon-type tubes), and silica (Silica gel 60), turning their surface catalytic without any additional synthetic step. This feature was exploited to transform standard tubing (Tygon, poly(ether ether ketone), and stainless steel) into flow reactors by simple passage of a solution of MW-PEI@AuNPs. This straightforward functionalization is especially appealing in the case of the stainless-steel tubing, one of the materials more widely used in HPLC, which is of interest for flow nanocatalysis. [ABSTRACT FROM AUTHOR]

This contribution describes the deposition of gold nanoparticles by microbial reduction of Au(III) ions using the mycelium of Mucor plumbeus. Biosorption as the major mechanism of Au(III) ions binding by the fungal cells and the reduction of them to the form of Au(0) on/in the cell wall, followed by the transportation of the synthesized gold nanoparticles to the cytoplasm, is postulated. The probable mechanism behind the reduction of Au(III) ions is discussed, leading to the conclusion that this process is nonenzymatic one. Chitosan of the fungal cell wall is most likely to be the major molecule involved in biomineralization of gold by the mycelium of M. plumbeus. Separation of gold nanoparticles from the cells has been carried out by the ultrasonic disintegration and the obtained nanostructures were characterized by UV-vis spectroscopy and transmission electron micrograph analysis. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1381-1392, 2017 [ABSTRACT FROM AUTHOR]

Sustainable methods are needed for rapid and efficient detection of environmental and food pollutants. The Sudan group of dyes has been used extensively as adulterants in food and also are found to be polluting the soil and water bodies. There have been several methods for detection of Sudan dyes, but most of them are not practical enough for common use. In this study, the electrochemical detection efficiency and stability of gold nanoparticle (AuNPs), silver NPs and Au–Ag bionanocomposites, synthesised by peanut skin extract, modified glassy carbon electrode has been investigated. The synthesised nanomaterial samples were characterised, for their quality and quantity, using ultra–visible spectroscopy, inductive coupled plasma mass spectrophotometer, Fourier transform infrared spectroscopy, energy‐dispersive X‐ray spectroscopy, high‐resolution transmission electron microscope and field emission scanning electron microscope. The nanomaterial hybrid electrodes showed great efficiency and stability in the detection of Sudan IV compared with the other previous electrodes. The peak current of the Sudan IV oxidation and reduction was found to be proportional to its concentration, in the range of 10–80 µM, with a detection limit of 4 µM. The hybrid electrodes showed 90% stability in detection for 20 cycles. [ABSTRACT FROM AUTHOR]

A de novo synthesis of gold-nanoparticle-embedded, nitrogen-doped nanoporous carbon nanoparticles (Au@NC) was investigated in this work. Chloroauroic acid was encapsulated inside zeolitic imidazolate framework-8 (ZIF-8) nanoparticles during the synthesis and later reduced into gold nanoparticles. The as-synthesized gold-nanoparticle-embedded ZIF-8 (Au@ZIF-8) was then carbonized into Au@NC to enhance the stability of the nanoporous support. The results show that Au@NC exhibits a porous structure containing 3 wt % of gold. 2-Methylimidazole provided an abundant amount of nitrogen (19 wt %) on the carbon matrix, which resulted in a hydrophilic and positively charged surface that is useful for the reduction of 4-nitrophenol. The results of the catalytic reaction indicate that synthesized Au@NC could act as an effective catalyst with a turnover frequency (TOF) of 1185 g−1 s−1, which is higher than that of conventional naked Au nanoparticles (TOF: 339 g−1 s−1) and that of Au nanoparticles on activated carbon (TOF: 89 g−1 s−1). We propose that the enhanced performance of Au@NC resulted from homogeneous distribution of Au nanoparticles along with the hydrophilic and positively charged nitrogen-doped carbon surface. [ABSTRACT FROM AUTHOR]

Nanobiotechnology has emerged as a fundamental domain in modern science, and metallic nanoparticles (NPs) are one of the largest classes of NPs studied because of their wide spectrum of possible applications in several fields. The use of plant extracts as reducing and stabilizing agents in their synthesis is an interesting and reliable alternative to conventional methodologies. However, the role of the different components of such extracts in the reduction/stabilization of metal ions has not yet been understood clearly. Here we studied the behavior of the main components of a Eucalyptus globulus Labill. bark aqueous extract during metal-ion reduction followed by advanced chromatographic techniques, which allowed us to establish their specific role in the process. The obtained results showed that phenolic compounds, particularly galloyl derivatives, are mainly responsible for the metal-ion reduction, whereas sugars are essentially involved in the stabilization of the NPs. [ABSTRACT FROM AUTHOR]