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A single-step laser scribing process is used to pattern nanostructured electrodes on paper-based devices. The facile and low-cost technique eliminates the need for chemical reagents or controlled conditions. This process involves the use of a CO2 laser to pyrolyze the surface of the paperboard, producing a conductive porous non-graphitizing carbon material composed of graphene sheets and composites with aluminosilicate nanoparticles. The new electrode material was extensively characterized, and it exhibits high conductivity and an enhanced active/geometric area ratio; it is thus well-suited for electrochemical purposes. As a proof-of-concept, the devices were successfully employed for different analytical applications in the clinical, pharmaceutical, food, and forensic fields. The scalable and green fabrication method associated with the features of the new material is highly promising for the development of portable electrochemical devices. [ABSTRACT FROM AUTHOR]

We have developed nanoparticle-embedded paper-spray mass spectrometry for studying three types of heterogeneously catalyzed reactions: 1) Palladium-nanoparticle-catalyzed Suzuki cross-coupling reactions, 2) palladium- or silver-nanoparticle-catalyzed 4-nitrophenol reduction, and 3) gold-nanoparticle-catalyzed glucose oxidation. These reactions were almost instantaneous on the nanocatalyst-embedded paper, which subsequently transferred the transient intermediates and products to a mass spectrometer for their detection. This in situ method of capturing transient intermediates and products from heterogeneous catalysis is highly promising for investigating the mechanism of catalysis and rapidly screening catalytic activity under ambient conditions. [ABSTRACT FROM AUTHOR]

The combination of electrogenerated chemiluminescence (ECL) and aptamer‐gated indicator delivering (gAID) magnetic mesoporous silica nanoparticles embedded into glass fibre paper functionalised with poly(ethyleneglycol) and N‐(3‐triethoxysilylpropyl)diethanolamine allowed the development of a rapid test that detects penicillin directly in diluted milk down to 50±9 ppt in <5 min. Covalent attachment of the aptamer "cap" to the silica scaffold enabled pore closure through non‐covalent electrostatic interactions with surface amino groups, while binding of penicillin led to a folding‐up of the aptamer thus releasing the ECL reporter Ru(bpy)32+ previously loaded into the material and letting it be detected after lateral flow by a smartphone camera upon electrochemical excitation with a screen printed electrode inserted into a 3D‐printed holder. The approach is simple, generic and presents advantages with respect to sensitivity, measurement uncertainty and robustness compared with conventional fluorescence or electrochemical detection, especially for point‐of‐need analyses of challenging matrices and analytes at ultra‐trace levels. [ABSTRACT FROM AUTHOR]

As a typical class of man‐made nanoreactors, metal‐loaded hollow carbon nanostructures (MHC nanoreactors) exhibit competitive potentials in the heterogeneous catalysis due to their tailorable microenvironment effects, in which the void‐confinement effect is one of the most fundamental functions in boosting the catalytic performance. Herein this paper, Ru‐loaded hollow carbon spheres are employed as nanoreactors with a crucial biomass hydrogenation process, levulinic acid (LA) hydrogenation into γ‐valerolactone, as the probe reaction to further recognize the forming mechanism of this pivotal effect. We demonstrated that the void‐confinement effect of the selected MHC nanoreactors is essentially driven by an integrating action of electronic metal‐support interaction, reactant enrichment and diffusion, which are mainly ascribed to peculiar properties of hollow nanoreactors both in electronic and structural aspects, respectively. This work offers a distinct case for interpreting the catalytic behaviour of MHC nanoreactors, which could potentially promise broader insights into the microenvironment engineering strategies of hollow nanostructures. [ABSTRACT FROM AUTHOR]

Water electrolysis is one of the most promising methods to produce H2 and O2 as high potential fuels. Comparing the two half‐reactions, the oxygen evolution reaction (OER) is the more difficult to be optimized and still relies on expensive noble metal‐based catalysts such as Ru or Ir. In this paper, we prepared nanoparticles of HfN and Hf2ON2 and tested them for the OER for the first time. The HfN sample, in particular, showed the highest activity, requiring an overpotential of only 358 mV at 10 mA cm−2 in Fe‐free electrolyte and, above all, exhibiting long‐term stability. This result places this system amongst one of the most promising catalysts for OER tested to date, in terms of sustainability, activity and stability. The prepared nanoparticles are small (less than 15 nm in diameter), well‐defined in shape and crystalline, and were characterised before and after electrochemical testing also via electron microscopy (EM), powder X‐ray diffraction (PXRD) and X‐ray photoelectron spectroscopy (XPS). [ABSTRACT FROM AUTHOR]

This paper describes the reversible control of the size of liquid-metal nanoparticles under ultrasonication. Gallium was utilized as a liquid metal, which has a melting point of 29.8 °C. Investigating the effects of ultrasonication (power, time, and temperature) on the formation of gallium nanoparticles revealed that the process is similar to the formation of oil in water (O/W) or water in oil (W/O) emulsions, as the temperature significantly affects the size of the gallium nanoparticles (GaNPs). Under ultrasonication, the balance between the break-up and coalescence of the GaNPs can be adjusted by changing the temperature or adding acid through modulating the natural surface oxide layer (which can be removed with acid) and the stabilizing effect of the surfactant dodecanethiol. Coalescence was predominant at higher temperatures, whereas particle break-up was found to be predominant at lower temperatures. Furthermore, the change in size was accompanied by a shift in the plasmonic absorption of the GaNPs in the UV region. [ABSTRACT FROM AUTHOR]

Ligand exchange is central in the processing of inorganic nanocrystals (NCs) and requires understanding of surface chemistry. Studying sterically stabilized HfO2 and ZrO2 NCs using 1H solution NMR and IR spectroscopy as well as elemental analysis, this paper demonstrates the reversible exchange of initial oleic acid ligands for octylamine and self-adsorption of oleic acid at NC surfaces. Both processes are incompatible with an X-type binding motif of carboxylic acids as reported for sulfide and selenide NCs. We argue that this behavior stems from the dissociative adsorption of carboxylic acids at the oxide surface. Both proton and carboxylate moieties must be regarded as X-type ligands yielding a combined X2 binding motif that allows for self-adsorption and exchange for L-type ligands. [ABSTRACT FROM AUTHOR]

The number of studies that have been published on the topic of nanosafety speaks for itself. We have seen an almost exponential rise over the past 15 years or so in the number of articles on nanotoxicology. Although only a couple of hundred papers had appeared on the topic of "Nanomaterials: environmental and health effects" before 2000, this number has exploded to over 10000 since 2001. Most of these studies, however, do not offer any kind of clear statement on the safety of nanomaterials. On the contrary, most of them are either self-contradictory or arrive at completely erroneous conclusions. Three years ago in this Journal we underscored the deficiencies in the way these studies were designed and pointed out the sources of error in the methods used. Now, on the basis of a comprehensive review of the literature and with the help of selected toxicological end points, we attempt to indicate where the significant weaknesses of these studies lie and what we must improve in the future. [ABSTRACT FROM AUTHOR]

When a colloidal drop dries on a surface, most of the particles accumulate at the drop periphery, yielding a characteristic ring-shaped pattern. This so-called coffee-ring effect (CRE) is observed in any pinned evaporating drop containing non-volatile solutes. Here, the CRE is dynamically controlled for the first time by using light, and an unprecedented reconfigurability of the deposit profile is demonstrated. This is achieved through a new mechanism where particle stickiness is optically tuned on demand, thus offering reliable modulation of the deposition pattern. The system consists of anionic nanoparticles and photosensitive cationic surfactants dispersed in water. It is shown that light-dependent modulation of surfactant-particle interactions dictates particle attraction and trapping at the liquid-gas interface, which allows us to direct particle deposition into a wide range of patterns from rings to homogeneous disks. Patterning from single drops is photoreversible upon changing the wavelength whereas spatial control in multiple drop arrays is achieved using a photomask. [ABSTRACT FROM AUTHOR]

The article talks about Jun Chen, Professor and Cheung Kong Scholar of Chemistry at Nankai University, Tianjin.His education and the awards won by him are mentioned. His views on his favorite food and scientists and songs and motivation and his top 5 research papers in the field of chemistry are also mentioned.

The article presents brief profile of Xiaoyuan (Shawn) Chen, senior investigator and laboratory chief, Laboratory of Molecular Imaging and Biomedicine, at the National Institute of Biomedical Imaging and Bioengineering in Bethesda, Maryland. Topics discussed include dumplings as his favorite food; Yesterday Once More as his favorite song and his research papers related to nanoparticles and carbon nanotubes.