http://www.mdpi.com/journal/materials/special_issues/metal-nanoparticles/ Dear Colleagues, Metal nanoparticles are full of contrasts: old but terribly contemporary, simple but present in highly sophisticated systems. From their beginning with Faraday for more than 150 years to current days, metal nanoparticles are present and important in our life, thanks to their optical properties, or use as drugs and antiseptics to give only some examples. Interestingly, today it is no more the question to create a nanoparticle – many procedures are known – but to know how to tailor their properties for a specific application and to understand how they form which is important. Size, shape, colloidal properties and optical activity control are prerequisites for various applications. Many parameters can be tuned to obtain the desired properties like template choice, temperature of synthesis, pH etc., making the Chemist work difficult but exciting and requiring a lot of inspiration and creativity. A further step of complexity can be found in metal nanoparticles like Janus-type, core-shell and nanoalloys, which are required for advanced analytical techniques and new materials preparation. In this field many questions are open but answers are scarce. Altogether, a lot remain to be done: design of new stabilizing ligands and templates, better knowledge of growth and self-assembly processes, and new analytical methods are required to answer the questions raised by this exiting research area. We hope that this special issue will contribute to solve open questions and open new tracks in this fascinating and rapidly moving area. Dr. Alexandre Mantion Guest Editor {snippet name="submission_info"} http://www.mdpi.com/1996-1944/4/2/368/ We study the assembling of small gold clusters subject to collisions and close contact coalescence by using molecular dynamics simulations to simulate events that occur typically in the sputtering process of synthesis. Our results support the notion that the kinetics of coalescence processes strongly determine the geometry and structure of the final particle. While impact velocities, relative orientations, and the initial shape of the interacting particles are unlikely to strictly determine the structural details of the newly formed particle, we found that high initial temperatures and/or impact velocities increase the probability of appearance of icosahedral-like structures, Wulff polyhedra are likely to be formed as a product of the interactions between nanospheres, while the appearance of fcc particles of approximately cuboctahedral shape is mainly due to the interaction between icosahedra. http://www.mdpi.com/1996-1944/4/2/368/ Fri, 28 Jan 2011 00:00:00 CET Materials 2011-01-28 4 2 Article 368 379 1996-1944 Coalescence and Collisions of Gold Nanoparticles 2011-01-28 doi: 10.3390/ma4020368 Joel Antúnez-García Sergio Mejía-Rosales Eduardo Pérez-Tijerina Juan Martín Montejano-Carrizales Miguel José-Yacamán http://www.mdpi.com/1996-1944/3/10/4842/ Nanotechnology has evolved to play a prominent role in our economy. Increased use of nanomaterials poses potential human health risk. It is therefore critical to understand the nature and origin of the toxicity imposed by nanomaterials (nanotoxicity). In this article we review the toxicity of the transition metal oxides in the 4th period that are widely used in industry and biotechnology. Nanoparticle toxicity is compellingly related to oxidative stress and alteration of calcium homeostasis, gene expression, pro-inflammatory responses, and cellular signaling events. The precise physicochemical properties that dictate the toxicity of nanoparticles have yet to be defined, but may include element-specific surface catalytic activity (e.g., metallic, semiconducting properties), nanoparticle uptake, or nanoparticle dissolution. These in vitro studies substantially advance our understanding in mechanisms of toxicity, which may lead to safer design of nanomaterials. http://www.mdpi.com/1996-1944/3/10/4842/ Mon, 25 Oct 2010 00:00:00 CEST Materials 2010-10-25 3 10 Review 4842 4859 1996-1944 Toxicity of Transition Metal Oxide Nanoparticles: Recent Insights from in vitro Studies 2010-10-25 doi: 10.3390/ma3104842 Yue-Wern Huang Chi-heng Wu Robert S. Aronstam http://www.mdpi.com/1996-1944/3/9/4626/ In the past few years, the synthesis of Cu nanoparticles has attracted much attention because of its huge potential for replacing expensive nano silver inks utilized in conductive printing. A major problem in utilizing these copper nanoparticles is their inherent tendency to oxidize in ambient conditions. Recently, there have been several reports presenting various approaches which demonstrate that copper nanoparticles can resist oxidation under ambient conditions, if they are coated by a proper protective layer. This layer may consist of an organic polymer, alkene chains, amorphous carbon or graphenes, or inorganic materials such as silica, or an inert metal. Such coated copper nanoparticles enable achieving high conductivities by direct printing of conductive patterns. These approaches open new possibilities in printed electronics, for example by using copper based inkjet inks to form various devices such as solar cells, Radio Frequency Identification (RFID) tags, and electroluminescence devices. This paper provides a review on the synthesis of copper nanoparticles, mainly by wet chemistry routes, and their utilization in printed electronics. http://www.mdpi.com/1996-1944/3/9/4626/ Wed, 08 Sep 2010 00:00:00 CEST Materials 2010-09-08 3 9 Review 4626 4638 1996-1944 Copper Nanoparticles for Printed Electronics: Routes Towards Achieving Oxidation Stability 2010-09-08 doi: 10.3390/ma3094626 Shlomo Magdassi Michael Grouchko Alexander Kamyshny