With laser beams, molecules can be fixed at exactly the right position in a three dimensional material. The new method can be used to grow biological tissue or to create micro sensors.
"3-D-photografting" is the name of the new method. Two research teams from the Vienna University of Technology collaborated closely to develop it: Professor Jürgen Stampfl's materials science team and Professor Robert Liska's research group for macromolecular chemistry. Both research groups have already attracted considerable attention in the past, developing new kinds of 3-D-printers.
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. The scientists start with a so-called hydrogel -- a material made of macromolecules, arranged in a loose meshwork. Between those molecules, large pores remain, through which other molecules or even cells can migrate. 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 µm could be obtained.
Depending on the application, different molecules can be used. 3-D photografting is not only useful for bio-engineering but also for other fields, such as photovoltaics or sensor technology. In a very small space, molecules can be positioned which attach to specific chemical substances and allow their detection. A microscopic three-dimensional "lab on a chip" becomes possible.