August 27, 2012

New Method Fixes Molecules On 3D Material

Lee Rannals for — Your Universe Online

Scientists are now able to fix molecules at exactly the right position in a three dimensional material using a new method.

Vienna University of Technology researchers developed a method to attach molecules at the right position on 3D objects on a micrometer scale, which could eventually be used to grow biological tissue or create micro sensors.

The "3D-photografting" method could be used to create a tiny 3D "lab on a chip" that could accurately position molecules to react with substances from the environment.

The scientists start with a material made from macromolecules that are arranged in a loose meshwork called hydrogel. They select molecules in the hydrogel meshwork, then certain points are irradiated with a laser beam.

Where the laser beam is most intense, a photochemically labile bond is broken, creating highly reactive intermediates which locally attach to the hydrogel very quickly. The precision of the laser beam depends on the laser's lens system.

“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”, Aleksandr Ovsianikov, a researcher on the project, said in a press release.

The method can be used to artificially grow biological tissue, similar to how a growing plant is able to cling to a rack.

In a natural tissue, the extracellular matrix uses specific amino acid sequences to signal to the cells where they are supposed to grow. Scientists are trying to use similar chemical signals in the lab.

During several experiments, cell attachment could be guided on two dimensional surfaces, but in order to grow larger tissues they need a three dimensional technique.

In developing micro sensors, 3D photografting can be used to position molecules to attach to specific chemical substances, and allow their detection. By using this technique, the researchers say that a microscopic 3D "lab on a chip" is able to be produced.