A researcher uses a pipette to put a sample on to a molography chip. Photograph of the experimental set-up in the ETH Zurich laboratory. (Credit: ETH Zurich/Andreas Frutiger)

Scientists have developed a completely new method for the analysis of molecules in liquids on a chip. The possible applications of this technology could revolutionize medical diagnostics, researchers say.

The new method is based on light diffraction on molecules on a small chip. Researchers say that in future, physicians may be able to perform complex examinations easily and quickly in their own practice.

The method also uses the key-lock principle of molecular recognition: for instance, in order to determine a particular protein dissolved in the blood (the key), it must dock on to a suitable antibody (the lock). In established immunological test methods, the “key in the lock” is made visible with a second color-coded key, but this step is no longer necessary in the new process – the “key in the lock” can be made visible directly with a laser light.

The scientists use a chip with a specially coated surface made up of tiny dots with a specific striped pattern. The molecules in question bind to the stripes but not to the interstices between the stripes. If a laser light is now directed along the chip’s surface, it is bent (diffracted) as a result of the special arrangement of the molecules in the pattern and focused on to a point below the chip. A point of light becomes visible. When the scientists put samples without the molecules on to the chip, the light is not bent and no point of light is visible.