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futurity_sci_tech 00170.txt

#An assembly line 3x thinner than a human hair Original Studyposted by Peter Ruegg-ETH Zurich on September 2 2014 Researchers have realized a long-held dream of building a nanoscale ssembly line.?It would enable us to assemble new complex substances or materials for specific applicationssays Professor Viola Vogel head of the Laboratory of Applied Mechanobiology at ETH Zurich Switzerland. The concept was inspired by the industrial assembly lines that churn out vehicles and electronics. A critical part of any assembly line is the mobile assembly carrier onto which an object is fixed. In a paper published in the latest issue of Lab on a Chip Vogel and her team presented a molecular assembly line featuring all the elements of a conventional production line: a mobile assembly carrier an assembly object assembly components attached at various assembly stations and a motor (including fuel) for the assembly carrier to transport the object from one assembly station to the next. At the nano level the assembly line takes the form of a microfluid platform into which an aqueous solution is pumped. This platform is essentially a canal system with the main canal just 30 micrometres wide three times thinner than a human hair. Several inflows and outflows lead to and from the canal at right angles. The platform was developed by Vogel s Phd student Dirk Steuerwald and the prototype was created in the clean room at the IBM Research Centre in Ruschlikon Switzerland. The canal system is fitted with a carpet made of the motor protein kinesin. This protein has two mobile heads that are moved by the energy-rich molecule ATP which supplies the cells of humans and other life forms with energy and therefore make it the fuel of choice in this artificial system. The researchers used microtubules as assembly carriers. Microtubules are string-like protein polymers that together with kinesin transport cargo around the cells. With its mobile heads kinesin binds to the microtubules and propels them forward along the surface of the device. This propulsion is supported further by the current generated by the fluid being pumped into the canal system. Five inflows and outflows direct the current in the main canal and divide it into strictly separated segments: a loading area from where the assembly carriers depart two assembly stations and two end stations where the cargo is delivered. The researchers can add the objects to the system through the lines that supply the assembly segments. In their most recent work they tested the system using Neutravidin the first molecule that binds to the nanoshuttle. A second component a single short strand of genetic material (DNA) then binds to the Neutravidin creating a small molecular complex. he system is still in its infancy. We re still far away from a technical applicationsays Vogel who believes they have shown merely that the principle works. She points out that although the construction of such a molecular nanoshuttle system may look easy a great deal of creative effort and knowledge from different disciplines goes into every single component of the system. The creation of a functional unit from individual components remains a big challenge. e have put a lot of thought into how to design the mechanical properties of bonds to bind the cargo to the shuttles and then unload it again in the right place. he use of biological motors for technical applications is not easy. Molecular engines such as kinesin have to be removed from their biological context and integrated into an artificial entity without any loss of their functionality. The researchers also had to consider how to build the assembly carriers and what the tracks and assembly stations would look like. hese are all separate problems that we have managed now to combine into a functioning wholesays Vogel. The researchers envision numerous applications including the selective modification of organic molecules such as protein and DNA the assembly of nanotechnological components or small organic polymers or the chemical alteration of carbon nanotubes. e need to continue to optimize the system and learn more about how we can design the individual components of this nanoshuttle system to make these applications possible in the futuresays Vogel

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