Gold nanoparticles

Also known as colloidal gold, gold nanoparticles are a sol or colloidal suspension of submicrometre-size nanoparticles of gold in a fluid, usually water. The liquid is usually either an intense red colour (for particles less than 100 nm) or blue/purple (for larger particles). Due to the unique optical, electronic, and molecular-recognition properties of gold nanoparticles, they are the subject of substantial research, with applications in a wide variety of areas, including electron microscopy, electronics, nanotechnology,and materials science.

The properties of colloidal gold nanoparticles, and thus their applications, depend strongly upon their size and shape. For example, rodlike particles have both transverse and longitudinal absorption peak, and anisotropy of the shape affects their self-assembly.

  • A study on thermophoretic Janus particles and capsules used as dyes for infrared laser‐assisted tissue welding.

    A) Production of Janus composite particles by LbL self‐assembly of PEM and magnetite nanoparticles followed by sputter coating with gold and resuspension in water. B) Laser tissue welding with magnetic assistance, due to magnetite particles being homogeneously distributed in the particles the particle orientation is random during welding. © 2016 Wenping He, Johannes Frueh, Narisu Hu, Liping Liu, Meiyu Gai, and Qiang He. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

    Researchers from China and London* recently published a principle study on thermophoretic Janus particles and capsules used as dyes for infrared laser‐assisted tissue welding. The original article “Guidable Thermophoretic Janus Micromotors Containing Gold Nanocolorifiers for Infrared Laser Assisted Tissue Welding” was published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

  • Active Implants: How Gold Binds to Silicone Rubber

    Thin film preparation scheme. a) Cross section of the organic molecular beam deposition setup for the fabrication of soft multi-layer nanostructures under ultra-high vacuum conditions. In situ spectroscopic ellipsometry at an incident angle of 20° simultaneously monitors film thickness, optical properties, and plasmonics. Representative schemes of thermally grown soft nanostructures: b) self-assembled Au particles bound to bi-functional, thiol-terminated PDMS; c) wrinkled Cr/PDMS; d) Au nanoparticles on a PDMS membrane. Coherent electron oscillations occur if the nanoparticles become excited at the resonance frequency. Due to the incident 4 × 10 mm2 beam dimension, SE monitors nanostructures over a macroscopic area. (© Wiley-VCH Verlag)

    Flexible electronic parts could significantly improve medical implants. However, electroconductive gold atoms usually hardly bind to silicones. Researchers from the University of Basel have now been able to modify short-chain silicones in a way, that they build strong bonds to gold atoms. The results have been published in the journal «Advanced Electronic Materials».

    Ultra-thin and compliant electrodes are essential for flexible electronic parts. When it comes to medical implants, the challenge lays in the selection of the materials, which have to be biocompatible. Silicones were particularly promising for application in the human body because they resemble the surrounding human tissue in elasticity and resilience. Gold also poses an excellent electrical conductivity but does only weakly bind to silicone, which results in unstable structures.

  • Artificial DNA can Control Release of Active Ingredients from Drugs

    Prof. Oliver Lieleg uses models to visualize how nanoparticles are bound together by DNA fragments. Such connections may become the basis of drugs that release their active ingredients in sequence. Uli Benz / TUM

    A drug with three active ingredients that are released in sequence at specific times: Thanks to the work of a team at the Technical University of Munich (TUM), what was once a pharmacologist's dream is now much closer to reality. With a combination of hydrogels and artificial DNA, nanoparticles can be released in sequence under conditions similar to those in the human body.

  • Hannover Messe: New hybrid inks for printed, flexible electronics without sintering

    New type of hybrid inks  allow electronic circuits to be applied to paper directly from a pen. Source: INM

    Research scientists at INM – Leibniz Institute for New Materials have now developed a new type of hybrid inks which allows electronic circuits to be applied to paper directly from a pen, for example. Flexible circuits can be produced inexpensively on foil or paper using printing processes and permit futuristic designs with curved diodes or input elements. This requires printable electronic materials that retain a high level of conductivity during usage in spite of their curved surfaces. Research scientists at INM – Leibniz Institute for New Materials have now developed a new type of hybrid inks which allows electronic circuits to be applied to paper directly from a pen, for example. They are usable after drying without any further processing.

  • HMI 2019: Conductive Metal-polymer Inks for Inkjet Printing: Flexible Electronics Without Sintering

    Flexible electronics without sintering. Free within this context; source: INM

    The INM – Leibniz Institute for New Materials presents hybrid inks for inkjet printing that contain metal nanoparticles coated with conductive polymers. The inks can be formulated in water and in other polar solvents and are suitable to print conductive structures on a range of substrates without any subsequent thermal or UV treatment. Standard metal inks require annealing after inkjet printing to become conductive. INM’s new inks obviate this step, making them compatible with many substrates including thin polymer foils and paper.

  • Nanostructures Made of Pure Gold

    Nanostructure made of gold.

    It is the Philosopher’s Stone of Nanotechnology: using a technological trick, scientists at TU Wien (Vienna) have succeeded in creating nanostructures made of pure gold.The idea is reminiscent of the ancient alchemists’ attempts to create gold from worthless substances: Researchers from TU Wien (Vienna) have discovered a novel way to fabricate pure gold nanostructures using an additive direct-write lithography technique. An electron beam is used to turn an auriferous organic compound into pure gold. This new technique can now be used to create nanostructures, which are needed for many applications in electronics and sensor technology. Just like with a 3D-printer on the nanoscale, almost arbitrary shapes can be created.

  • Physiker beobachten weltweit erstmals, wie Nano-Goldpartikel durch Zellmembranen wandern

    Lipidbeschichtete, hydrophobe Gold-Nanopartikel durchqueren eine Doppellage, die als künstliche Zellmembran angesehen werden kann. Grafik: Vladimir Baulin

    Die OECD berichtete jüngst (Link s.u.), dass Nanopartikel in mehr als 1300 kommerziellen Produkten enthalten sind, deren potenziell toxische Wirkung ausgeblendet wird. Die Mechanismen, wie diese Partikel durch menschliches Gewebe wandern, sind noch weitestgehend unverstanden. Ein Team aus spanischen und saarländischen Physikern konnte nun weltweit erstmals in Echtzeit beobachten, wie eine bestimmte Art von Nanopartikeln durch eine künstliche Zellwand wandert. Damit haben sie den Grundstein für weitere Forschungen gelegt, die im sicheren Umgang mit den winzigen Teilchen helfen sollen. Die Studie ist am 2. November in der Fachzeitschrift Science Advances erschienen.

  • Researchers Develop a Solid Material with Mobile Particles that React to the Environment

    At high temperatures (left) particles move freely in the droplets and lend the material a ruby red color; they agglomerate at lower temperatures (right) and change the material’s color to grey-violet. Copyright: INM; free within this press release

    Inside most materials, little is moving. But a new “active nanocomposite” is teeming with motion: small particles connect or separate, thus changing the color of the entire material. It was made by scientists of the Leibniz Institute for New Materials in Saarbrücken in an attempt to lend materials more dynamics. The transparent material can “answer” temperature changes or, in the future, the presence of chemical substances and toxins with a color change. The researchers want to create packaging films that change their color when food spoils, for example.

  • Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

    GNOME laser transfection can continuously achieve high vitality rates of over 80% in primary cells (here: cortical neurons). Photo: LZH

    Transfecting a larger number of cells gently and efficiently – this is possible using the GNOME technology of the Laser Zentrum Hannover e.V. (LZH). This technology is especially suitable for high throughput screening. For the first time, the LZH will be presenting this innovative technology at the Labvolution 2017 at the Pavilion of the State of Lower Saxony (hall 19/20, stand C80).