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• Selenium needle-like structure synthesized by pulsed laser ablation. • Trigonal-selenium needles grown from amorphous-selenium nanoparticles. • Growth achieved within 24 h in Ethanol. Elongated stuctures, needle-like type, of trigonal selenium were synthesized successfully by pulsed laser ablation in ethanol. The aspect-ratio was controlled by tuning the repetition rate of the laser beam from 0.1 kHz to 19.9 kHz. Five minutes irradiation followed up by one day of aging inside the colloid was required to achieve the needle-like structure in ethanol. [ABSTRACT FROM AUTHOR]

The nickel-cobalt system is an important alloy in nanotechnology because of its ferromagnetic properties, high thermal stability and shape memory effect. At the nanoscale, its physico-chemical properties become size-, shape- and composition- dependent. However, those properties are still mostly unknown at the nanoscale. Therefore, this manuscript fills this gap in knowledge. Indeed, when the size of the alloy is reduced, the entire phase diagram undergoes a vertical shift downward to lower temperatures, and a tilt caused by a larger size effect affecting cobalt than nickel. Among the most commonly observed shapes, the thermal stability of nickel-cobalt nanoparticles was determined as a function of their size and composition. Furthermore, the ferromagnetic-paramagnetic phase transition and martensitic transformation for those shapes were calculated as a function of the nickel-cobalt alloy composition. As expected, the ferromagnetic and martensitic regions shrunk at the nanoscale; but the martensitic transformation was less affected by size effects compared to magnetic and thermal (melting) transitions. [ABSTRACT FROM AUTHOR]

Gold–copper (Au–Cu)phases were employed alreadyby pre-Columbian civilizations, essentially in decorative arts, whereasnowadays, they emerge in nanotechnology as an important catalyst.The knowledge of the phase diagram is critical to understanding theperformance of a material. However, experimental determination ofnanophase diagrams is rare because calorimetry remains quite challengingat the nanoscale; theoretical investigations, therefore, are welcomed.Using nanothermodynamics, this paper presents the phase diagrams ofvarious polyhedral nanoparticles (tetrahedron, cube, octahedron, decahedron,dodecahedron, rhombic dodecahedron, truncated octahedron, cuboctahedron,and icosahedron) at sizes 4 and 10 nm. One finds, for all the shapesinvestigated, that the congruent melting point of these nanoparticlesis shifted with respect to both size and composition (copper enrichment).Segregation reveals a gold enrichment at the surface, leading to akind of core–shell structure, reminiscent of the historicalartifacts. Finally, the most stable structures were determined tobe the dodecahedron, truncated octahedron, and icosahedron with aCu-rich core/Au-rich surface. The results of the thermodynamic approachare compared and supported by molecular-dynamics simulations and byelectron-microscopy (EDX) observations. [ABSTRACT FROM AUTHOR]

Quantum effects becomes more and more pronounced at the nanoscale. However, the size where those effects appear strongly depends on the nature of the semiconductor. This paper presents a simple methodology to calculate precisely the size where quantum effects appear for each individual semiconductor. This critical size is calculated from the bulk energy bandgap, index of refraction or dielectric constant of the semiconductor. This work paves the way to experimentalists who will now be able to precisely determine in which confinement regime their semiconductor nanostructure belongs to. Trends within the two most important group of semiconductors, II-VI and III-V, are also clarified based on the spin-orbit coupling. Image 1 [ABSTRACT FROM AUTHOR]

An introduction to the reports published within the issue are presented including on structural and electronic properties of quantum, molecular dynamics simulation and the use of silica nanoparticles in the preparation of nanocomposites.

Due to the massive use of antibiotics in agriculture, bacteria developed strategies to survive and this is causing the spread of Antibiotic Resistant Bacteria killing several hundred thousand people worldwide. In this paper, zinc oxide nanoparticles (ZnO NPs) synthesized by a sol-gel technique, are proposed as a potential solution against a variety of Gram-negative, Gram-positive and sensitive or multidrug-resistant (MDR) bacteria. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. We found ZnO NPs were effective against Escherichia coli wild type, Escherichia coli producing carbapenemase (CRE), Klebsiella pneumoniae wild type, and Klebsiella pneumoniae producing Extended Spectrum Beta-lactamase (ESBL) wild type (SAT), Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-sensitive Staphylococcus aureus (MSSA). • Zinc oxide nanoparticles against multidrug-resistant bacteria. • Bactericidal activity of ZnO NPs sol-gel synthesis. • Future prospects of ZnO-based materials in developing alternative solutions to fight the rise of bacterial infections. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis and detailed structural characterization of novel helical gold-copper nanowires. The nanowires possess the Boerdijk-Coxeter-Bernal structure, based on the pile up of octahedral, icosahedral, and/or decahedral seeds. They are self-assembled into a coiled manner as individual wires or into a parallel-ordering way as groups of wires. The helical nanowires are ultrathin with a diameter of less than 10 nm and variable length of several micrometers, presenting a high density of twin boundaries and stacking faults. To the best of our knowledge, such gold-copper nanowires have never been reported previously. [ABSTRACT FROM AUTHOR]

Cancer and antimicrobial resistance to antibiotics are two of the most worrying healthcare concerns that humanity is facing nowadays. Some of the most promising solutions for these healthcare problems may come from nanomedicine. While the traditional synthesis of nanomaterials is often accompanied by drawbacks such as high cost or the production of toxic by-products, green nanotechnology has been presented as a suitable solution to overcome such challenges. In this work, an approach for the synthesis of tellurium (Te) nanostructures in aqueous media has been developed using aloe vera (AV) extracts as a unique reducing and capping agent. Te-based nanoparticles (AV-TeNPs), with sizes between 20 and 60 nm, were characterized in terms of physicochemical properties and tested for potential biomedical applications. A significant decay in bacterial growth after 24 h was achieved for both Methicillin-resistant Staphylococcus aureus and multidrug-resistant Escherichia coli at a relative low concentration of 5 µg/mL, while there was no cytotoxicity towards human dermal fibroblasts after 3 days of treatment. AV-TeNPs also showed anticancer properties up to 72 h within a range of concentrations between 5 and 100 µg/mL. Consequently, here, we present a novel and green approach to produce Te-based nanostructures with potential biomedical applications, especially for antibacterial and anticancer applications. [ABSTRACT FROM AUTHOR]

Physicochemical, electrochemical and biological performance of 4 types of all-carbon nanotube layers was studied. Higher oxidation state of carbon was responsible for micro-scaled uniformity of the layers and excellent electrical conductivity, while nitrogen containing functional groups yielded materials with anisotropy similar to natural tissues and reduced work function. All materials were cytocompatible with mammalian fibroblasts (viability >80%, cytotoxicity <3% at day 7) and human dermal fibroblast (viability of cells >70% at day 1), while reducing bacterial and cancer cells proliferation without adding any drug. After 8 h culture, a ~50% depletion in the number of Gram-positive bacteria was observed on materials with lower work function, while Gram-negative bacteria were more sensitive towards carbon coordination number and presence of nitrogen atoms (cell depletion of up to 48% on amidized carbon nanotubes). After 1-day culture, >80% reduction in the melanoma cells number, connected with enhanced production of reactive oxygen species (ROS) was observed. All-carbon nanotube layers decreased bacteria and cancer cell functions without negatively influencing mammalian cells nor using drugs and we believe that this can be explained by various sensitivity of the tested cells towards exogenous ROS overproduction. As the concerns over implant-related infections as well as rates of antibiotic-resistant bacteria and chemotherapeutic-resistant cancer cells are growing, such materials should pave the way for a wide range of biomedical applications. Unlabelled Image • 4 types of all-carbon nanotubes layers are fabricated via electrophoretic deposition. • All materials are biocompatible and electrically conductive. • The lower the work the work function, the stronger inhibition of Gram + bacteria. • Gram- bacteria are inhibited by higher coordination number of Carbon. • Anticancer properties are connected with reactive oxygen species generation. [ABSTRACT FROM AUTHOR]