{"71341":{"#nid":"71341","#data":{"type":"news","title":"Fast AFM Probes Measure Many Biomolecule or Material Properties","body":[{"value":"\u003Cp\u003ENew research demonstrates that novel probe technology based on flexible membranes can replace conventional atomic force microscopy (AFM) cantilevers for applications such as fast topographic imaging, quantitative material characterization and single molecule mechanics measurements.\u003C\/p\u003E\n\u003Cp\u003EIn addition to the standard AFM topography scan, these novel probes simultaneously measure material properties including adhesion, stiffness, elasticity and viscosity. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022Our probes attach directly to AFM systems currently on the market and can collect topography measurements at least 50 times faster than traditional cantilevers because they use electrostatic forces between the membrane and an electrode to move the tip,\u0022 said Levent Degertekin, a professor in the George W. Woodruff School of Mechanical Engineering at Georgia Tech. The research team also includes Guclu Onaran and Hamdi Torun, graduate students in the Georgia Tech School of Electrical and Computer Engineering.\n\u003C\/p\u003E\n\u003Cp\u003EDetails of the novel force sensing integrated readout and active tip (FIRAT) probe and its biological applications were presented at the American Physical Society meeting in March. This research was funded by the National Institutes of Health and the National Science Foundation.\n\u003C\/p\u003E\n\u003Cp\u003EIn current AFM systems, the sample surface is scanned by a cantilever with a sharp tip just a few nanometers in diameter at the end. An optical beam is bounced off the cantilever tip to measure the deflection of the cantilever as the sharp tip moves over the surface and interacts with the material being analyzed to determine the topography of the surface.\n\u003C\/p\u003E\n\u003Cp\u003EThe new probe replaces the cantilever with a drum-like membrane from which a tip extends to scan the material sample. In one scanning mode, as the tip moves above a surface, it lightly taps the material. With each tap, the instrument gathers precise information about both the tip\u0027s position and the forces acting on it, sensing the shape of the material and how stiff and sticky it is.\n\u003C\/p\u003E\n\u003Cp\u003EAn output signal is generated only when there is an interaction force on the probe. In other words, transient interaction forces can be measured during each \u0027tap\u0027 of the tip with high resolution and without any background signal. \n\u003C\/p\u003E\n\u003Cp\u003EIn the February 27, 2008 issue of the journal \u003Cem\u003ENanotechnology\u003C\/em\u003E, the researchers described using the FIRAT probe to characterize the elasticity, surface energy and adhesion hysteresis of three polymers and a silicon sample. The quantitative results were mapped in addition to topography.\n\u003C\/p\u003E\n\u003Cp\u003EFIRAT probes made of dielectric materials with embedded actuation electrodes have also been designed for operation in liquids. The design of these membrane-based probes also makes them relatively easy to arrange in arrays in which each probe can move independently. One application of such an array is fast parallel measurements of forces between biological molecules.\n\u003C\/p\u003E\n\u003Cp\u003EIn collaboration with Cheng Zhu, Regents\u0027 Professor in the Wallace H. Coulter Department of Biomedical Engineering, Degertekin is using the probe to measure the force between two interacting biological molecules and unbinding forces between two molecules. \n\u003C\/p\u003E\n\u003Cp\u003EBy testing different molecules and buffer solutions, researchers can determine the probability of molecule adhesion, a process that requires many repetitive measurements. This has implications in drug discovery, where determining how frequently certain soft biological molecules adhere to each other is important. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022Rather than moving a single cantilever up and down a thousand times, we have developed a membrane that would allow parallel measurements of molecules to get thousands of measurements at one time,\u0022 said Degertekin. \n\u003C\/p\u003E\n\u003Cp\u003EThis new technique was described in the February 2007 issue of the journal \u003Cem\u003ENanotechnology\u003C\/em\u003E.  For different applications, Degertekin can adjust the stiffness of the membranes.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022The best mechanical measurements of surfaces or biomolecules are obtained when the probe stiffness matches the sample stiffness,\u0022 explained Degertekin. \u0022If you use a piezoelectric or any other linear actuator, you don\u0027t have that phenomenon - you cannot soften things.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EBy electrically changing the spring constant of the FIRAT probe, Degertekin can adjust the stiffness of the membranes, providing the ability to use the same probe to identify the mechanical properties of different samples - some soft and some stiff. This research was published in the December 2007 issue of the journal \u003Cem\u003EApplied Physics Letters\u003C\/em\u003E.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022We know these probes improve the speed of AFM scans and provide increased information about a sample,\u0022 said Degertekin. \u0022The next step is to batch fabricate them so that all researchers using AFM systems can benefit from these probes.\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\n\u003C\/strong\u003E\u003C\/p\u003E\n\u003Cp\u003EMedia Relations Contacts: Abby Vogel (404-385-3364); E-mail: (\u003Ca href=\u0022mailto:avogel@gatech.edu\u0022\u003Eavogel@gatech.edu\u003C\/a\u003E) or John Toon (404-894-6986); E-mail: (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EWriter:\u003C\/strong\u003E Abby Vogel\n\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Probes simultaneously measure topography, adhesion, stiffness, elasticity and viscosity"}],"field_summary":[{"value":"Researchers have developed novel atomic force microscopy (AFM) probes that can quickly and simultaneously measure biomolecule or material properties including adhesion, stiffness, elasticity and viscosity, in addition to the standard AFM topography scan.","format":"limited_html"}],"field_summary_sentence":[{"value":"Fast AFM probes prove valuable for biological applications"}],"uid":"27206","created_gmt":"2008-04-15 00:00:00","changed_gmt":"2016-10-08 03:03:24","author":"Abby Vogel Robinson","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2008-04-15T00:00:00-04:00","iso_date":"2008-04-15T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"71342":{"id":"71342","type":"image","title":"Levent Degertekin AFM holder","body":null,"created":"1449177367","gmt_created":"2015-12-03 21:16:07","changed":"1475894634","gmt_changed":"2016-10-08 02:43:54"},"71343":{"id":"71343","type":"image","title":"AFM topography scan","body":null,"created":"1449177367","gmt_created":"2015-12-03 21:16:07","changed":"1475894634","gmt_changed":"2016-10-08 02:43:54"},"71344":{"id":"71344","type":"image","title":"AFM holder","body":null,"created":"1449177367","gmt_created":"2015-12-03 21:16:07","changed":"1475894634","gmt_changed":"2016-10-08 02:43:54"}},"media_ids":["71342","71343","71344"],"related_links":[{"url":"http:\/\/dx.doi.org\/10.1088\/0957-4484\/18\/16\/165303","title":"2007 Nanotechnology article"},{"url":"http:\/\/dx.doi.org\/10.1063\/1.2827190","title":"Applied Physics Letters article"},{"url":"http:\/\/dx.doi.org\/10.1088\/0957-4484\/19\/8\/085704","title":"2008 Nanotechnology article"},{"url":"http:\/\/www.me.gatech.edu\/","title":"George W. Woodruff School of Mechanical Engineering"},{"url":"http:\/\/www.me.gatech.edu\/faculty\/degertekin.shtml","title":"Levent Degertekin"}],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"141","name":"Chemistry and Chemical Engineering"},{"id":"145","name":"Engineering"},{"id":"146","name":"Life Sciences and Biology"},{"id":"149","name":"Nanotechnology and Nanoscience"},{"id":"135","name":"Research"}],"keywords":[{"id":"7437","name":"adhesion"},{"id":"3013","name":"atomic force microscopy"},{"id":"7442","name":"cantilever"},{"id":"3175","name":"elasticity"},{"id":"7441","name":"FIRAT"},{"id":"4185","name":"interaction"},{"id":"7435","name":"material"},{"id":"7440","name":"membrane"},{"id":"2557","name":"mems"},{"id":"2071","name":"molecule"},{"id":"989","name":"probe"},{"id":"7436","name":"properties"},{"id":"170880","name":"stiffness"},{"id":"7439","name":"topography"},{"id":"7424","name":"viscosity"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cstrong\u003EAbby Robinson\u003C\/strong\u003E\u003Cbr \/\u003EResearch News and Publications\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=avogel6\u0022\u003EContact Abby Robinson\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-385-3364\u003C\/strong\u003E","format":"limited_html"}],"email":["abby@innovate.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}