Vienna University of Technology researchers develop 3D photografting technology



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3-D pattern, produced by photografting (180 μm wide). Fluorescent molecules are attached to the hydrogel, resulting in a microscopic 3-D pattern.

While there are many ways to create 3D objects on a micrometer scale, scientists at the Vienna University of Technology have developed a method to attach chemical 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, 3D photografting, also holds promise for sensor technology. The technology could, for example, create a miniature three dimensional lab on a chip in which accurately positioned molecules react with substances from the environment.?? Two research teams, Professor Jürgen Stampfl's materials science team and Professor Robert Liska's research group for macromolecular chemistry at the Vienna University of Technology, collaborated closely to develop the technology. Both research groups have already attracted 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 — Laser locked positioning? 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. Researchers at the Vienna University of Technology obtained a resolution of 4 μm. "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 Ovsianikov. ???Micro Sensors Detect Molecules Different applications can make use of different molecules. 3D photografting is not only useful for bio-engineering but also for other fields, such as photovoltaics or sensor technology. The process can precisely position in a very small space molecules that attach to specific chemical substances and allow their detection. Vienna University of Technology Deeplink to research abstracts??