Two research teams from the Vienna University of Technology collaborated closely to develop a new method called “3D-photografting”. Professor Jürgen Stampfl’s materials science team and Professor Robert Liska’s research group for macromolecular chemistry.
The teams developed a method to attach molecules at exactly the right place. We’re talking about three dimensional objects on a micrometer scale here. There are already many ways to do this but what makes this method so special is that the chemical properties of the materials can be tuned at micrometer precision. 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.
How it works
This new method is not exactly the same as 3D printing. 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.”
With laser beams, molecules can be fixed at exactly the right position in a three dimensional material. 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. “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.
What it can be used for
Depending on the application, different molecules can be used. 3D 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.
Source: Vienna University of Technology