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by Staff Writers
Vienna, Austria (SPX) Aug 28, 2012
With laser beams, molecules can be fixed at exactly the right position in a three dimensional material. The new method developed at the Vienna University of Technology can be used to grow biological tissue or to create micro sensors.
There are many ways to create three dimensional objects on a micrometer scale. But how can the chemical properties of a material be tuned at micrometer precision? Scientists at the Vienna University of Technology developed a method to attach molecules at exactly the right place. When biological tissue is grown, this method can allow the positioning of chemical signals, telling living cells where to attach. The new technique also holds promise for sensor technology: A tiny three dimensional "lab on a chip" could be created, in which accurately positioned molecules react with substances from the environment.
Materials Science and Chemistry
Both research groups have already attracted considerable attention in the past, developing new kinds of 3D-printers. However, for the applications on which the scientists are working on now, 3D-printing would not have been useful: "Putting together a material from tiny building blocks with different chemical properties would be extremely complicated", says Aleksandr Ovsianikov. "That is why we start from a three dimensional scaffold and then attach the desired molecules at exactly the right positions."
Molecules in the Hydrogel - Locked into Position by the Laser
Specially selected molecules are introduced into the hydrogel meshwork, then certain points are irradiated with a laser beam. At the positions where the focused laser beam is most intense, a photochemically labile bond is broken. That way, highly reactive intermediates are created which locally attach to the hydrogel very quickly.
The precision depends on the laser's lens system, at the Vienna University of Technology a resolution of 4 m could be obtained. "Much like an artist, placing colors at certain points of the canvas, we can place molecules in the hydrogel - but in three dimensions and with high precision", says Aleksandr Ovsianikov.
Chemical Signals for Cells
In various experiments, cell attachment could be guided on two dimensional surfaces, but in order to grow larger tissues with a specific inner structure (such as capillaries), a truly three dimensional technique is required.
Micro Sensors Detect Molecules
Space Technology News - Applications and Research