{"46239":{"#nid":"46239","#data":{"type":"news","title":"Bio-enabled Technique Produces Nanoparticle Composites","body":[{"value":"\u003Cp\u003EUsing thin films of silk as templates, researchers have incorporated inorganic nanoparticles that join with the silk to form strong and flexible composite structures that have unusual optical and mechanical properties.  This bio-enabled, surface-mediated approach mimics the growth and assembly processes of natural materials, taking advantage of the ability of biomolecules to chemically reduce metal ions to produce nanoparticles -- without harsh processing conditions.\u003C\/p\u003E\n\u003Cp\u003ELess than 100 nanometers thick, silk-silver nanoparticle composite films formed in this process can be used as flexible mirrors. The technique could also be used to create films that reflect light in specific wavelengths, anti-microbial coatings, thin film sensors, self-cleaning coatings, catalytic materials and potentially even flexible photovoltaic cells.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022We are taking advantage of biological molecules that have the ability to bind metallic ions of silver or gold from solution,\u0022 said Vladimir Tsukruk, a professor in the Georgia Tech School of Materials Science and Engineering.  \u0022These molecules can create mono-dispersed metallic nanoparticles of consistent sizes under ambient conditions -- at room temperature and in a water-based environment without high vacuum or high temperatures.\u0022\n\u003C\/p\u003E\n\u003Cp\u003ESponsored by the Air Force Office of Scientific Research and the Air Force Research Laboratory, the research was described August 19 at the Fall 2009 National Meeting of the American Chemical Society.\n\u003C\/p\u003E\n\u003Cp\u003EThe nanoparticles produced range in size from four to six nanometers in diameter, surrounded by a biological shell of between one and two nanometers.  The silk template permits good control of the nanoparticle placement, creating a composite with equally dispersed particles that remain separate.  The optical properties of the resulting film depend on the nanoparticle material and size.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022This system provides very precise control over nanoparticle sizes,\u0022 said Eugenia Kharlampieva, a postdoctoral researcher in Tsukruk\u0027s laboratory.  \u0022We produce well-defined materials without the problem of precipitation, aggregation or formation of large crystals.  Since the silk fibroin is mono-dispersed, we can create uniform domains within the template.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EFabrication of the nanocomposites begins by dissolving silk cocoons and making the resulting fibroin water soluble.  The silk is then placed onto a silicon substrate using a spin-coating technique that produces multiple layers of thin film that is then patterned into a template using a nanolithography technique.  \n\u003C\/p\u003E\n\u003Cp\u003E\u0022Because silk is a protein, we can control the properties of the surface and design different kinds of surfaces,\u0022 explained Kharlampieva.  \u0022This surface-mediated approach is flexible at producing different shapes.  We can apply the method to coat any surface we want, including objects of complex shapes.\u0022\n\u003C\/p\u003E\n\u003Cp\u003ENext, the silk template is placed in a solution containing ions of gold, silver, or other metal.  Over a period of time ranging from hours to days, nanoparticles form within the template.  The relatively long growth process, which operates at room temperature and neutral pH in a water-based environment, allows precise control of the particle size and spacing, Tsukruk notes. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022We operate at conditions that are suitable for biological activities,\u0022 he explained.  \u0022No reducing agents are required to produce the particles because the biomolecules serve as reducing agents.  We don\u0027t add any chemicals that could be toxic to the protein.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EUse of these mild processing conditions could reduce the cost of producing the composites and their potential environmental impact. When dried, the resulting silk-nanoparticle film has high tensile strength, high elasticity and toughness.  \n\u003C\/p\u003E\n\u003Cp\u003E\u0022Silk is almost as strong as Kevlar, but it can be deformed by 30 percent without breaking,\u0022 said Tsukruk.  \u0022The silk film is very robust, with a complicated structure that you don\u0027t find in synthetic materials.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EFor the future, the researchers plan to use the bio-assisted, surface-mediated technique to produce nanoparticles from other metals.  They also hope to combine different types of particles to create new optical and mechanical properties.  \n\u003C\/p\u003E\n\u003Cp\u003E\u0022If we combine gold-binding and silver-binding peptides, we can make composites that will include a mixture of gold and silver nanoparticles,\u0022 said Kharlampieva.  \u0022Each particle will have its own properties, and combining them will create more interesting composite materials.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EThe researchers also hope to find additional applications for the films in such areas as photovoltaics, medical technology and anti-microbial films that utilize the properties of silver nanoparticles.\n\u003C\/p\u003E\n\u003Cp\u003EBeyond Tsukruk and Kharlampieva, the research team has included Dmitry Zimnistky, Maneesh Gupta and Kathryn Bergman of Georgia Tech; David Kaplan of the Department of Biomedical Engineering at Tufts University, and Rajesh Naik of the Materials and Manufacturing Directorate of the Air Force Research Laboratory at Wright-Patterson Air Force Base.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022Nanomaterials grown under environmentally friendly conditions can be as good as synthetic materials that are produced under harsh conditions,\u0022 Tsukruk added.  \u0022This technique allows us to grow very useful materials under natural conditions.\u0022\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\nGeorgia Institute of Technology\u003Cbr \/\u003E\n75 Fifth Street, N.W., Suite 100\u003Cbr \/\u003E\nAtlanta, Georgia  30308  USA\u003C\/strong\u003E\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contacts\u003C\/strong\u003E: John Toon (404-894-6986); E-mail: (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E) or Abby Vogel (404-385-3364); E-mail: (\u003Ca href=\u0022mailto:avogel@gatech.edu\u0022\u003Eavogel@gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003ETechnical Contact\u003C\/strong\u003E: Vladimir Tsukruk\u003Cbr \/\u003E\n(404-894-6081); E-mail: (\u003Ca href=\u0022mailto:vladimir@mse.gatech.edu\u0022\u003Evladimir@mse.gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\n\u003C\/p\u003E\n\u003Cp\u003E\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Thin Films of Silk Produce and Combine with Metallic Particles"}],"field_summary":[{"value":"Using thin films of silk as templates, researchers have incorporated inorganic nanoparticles that join with the silk to form strong and flexible composite structures that have unusual optical and mechanical properties.","format":"limited_html"}],"field_summary_sentence":[{"value":"Nanoparticles and silk form composites with unique properties"}],"uid":"27303","created_gmt":"2009-08-19 00:00:00","changed_gmt":"2016-10-08 03:03:14","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2009-08-19T00:00:00-04:00","iso_date":"2009-08-19T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"46240":{"id":"46240","type":"image","title":"Analyzing nanocomposites","body":null,"created":"1449174358","gmt_created":"2015-12-03 20:25:58","changed":"1475894414","gmt_changed":"2016-10-08 02:40:14","alt":"Analyzing nanocomposites","file":{"fid":"101038","name":"tra16332.jpg","image_path":"\/sites\/default\/files\/images\/tra16332_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tra16332_0.jpg","mime":"image\/jpeg","size":1270523,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tra16332_0.jpg?itok=m6y1pct9"}},"46241":{"id":"46241","type":"image","title":"Gold nanoparticles","body":null,"created":"1449174358","gmt_created":"2015-12-03 20:25:58","changed":"1475894414","gmt_changed":"2016-10-08 02:40:14","alt":"Gold nanoparticles","file":{"fid":"101039","name":"tpc16332.jpg","image_path":"\/sites\/default\/files\/images\/tpc16332_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tpc16332_0.jpg","mime":"image\/jpeg","size":46485,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tpc16332_0.jpg?itok=IXYCMpej"}}},"media_ids":["46240","46241"],"related_links":[{"url":"http:\/\/www.mse.gatech.edu\/FacultyStaff\/MSE_Faculty_researchbios\/Tsukruk\/tsukruk.html","title":"Vladimir Tsukruk"},{"url":"http:\/\/www.mse.gatech.edu\/","title":"Georgia Tech School of Materials Science and Engineering"}],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"145","name":"Engineering"},{"id":"149","name":"Nanotechnology and Nanoscience"},{"id":"135","name":"Research"}],"keywords":[{"id":"6189","name":"Nanocomposites"},{"id":"2973","name":"nanoparticles"},{"id":"170843","name":"silk"},{"id":"7090","name":"templates"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cstrong\u003EJohn Toon\u003C\/strong\u003E\u003Cbr \/\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=jt7\u0022\u003EContact John Toon\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-894-6986\u003C\/strong\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}