A chip that can be used to track biological processes in three dimensions inside living cells has been developed in France.

Aurélien Bancaud and co-workers from the University of Toulouse, made the device, which uses microscale V-shaped mirrors to provide simultaneous views of biological specimens from different vantages. This allows the team to use a regular upright microscope to follow cell processes in 3D on a fast timescale.

Bancaud's mirrored chip can be used to study chromatin dynamics inside cells

'Modern live cell imaging calls for the new methods that achieve fast and minimally invasive 3D observation,' explains Bancaud. Current methods can involve acquiring several views of the same specimen, meaning high doses of illumination are needed - which can be detrimental to the cells. The multiple observation process is also slower, so fast events cannot be easily tracked. Pyramidal mirrors have been proposed for multiple vantage point imaging and 3D tracking in vitro, but these systems were not integrated in a lab-on-a-chip device, limiting their applicability for live cell imaging, says Bancaud.

Bancaud's group made the device using micromachining technology to form metal coated trenches in a silicon wafer. The metal coating acts as a mirror and particles such as cells can be introduced into the V-shaped trenches. The researchers incorporated their device into a standard fluorescence microscope and loaded the wafer with yeast cells modified to express a fluorescent protein. The group was able to use the device to follow the fluorescent protein and so study fast DNA movements in chromosomes within the cell nuclei.

Enrico Gratton, an expert in fluorescence microscopy for imaging live cells from University of California, Irvine, US, says the lab-on-chip device is 'a very clever use of microfabrication. The advantage of the method is that it only requires a normal wide field microscope and the chip,' he adds. 

Bancaud suggests that in future the technology might be useful for observing processes in cells from different biological systems where fast tracking is necessary. He adds that it might be tempting to try adding temperature sensors or actuators to this type of device, to further control the cell environment.

Fay Nolan-Neylan

Enjoy this story? Spread the word using the 'tools' menu on the left or add a comment to the Chemistry World blog.