25 September 2012

Barcode for cells from DNA molecules and fluorophores

The biological analogue of the barcode will expand the possibilities of research

Andrey Vasilkov, Computerra-Online based on the materials of the Wyss Institute: Researchers at Harvard's Wyss Institute Engineer Novel DNA BarcodeThe Wyss Institute of Bioengineering at Harvard University has developed a new way of labeling biological microstructures, called "DNA barcode".

The method is based on the natural ability of DNA to self-assemble and expands the possibilities of color coding used in fluorescence microscopy.

Various variants of fluorescence microscopy are based on the fact that the molecules of the test sample absorb light quanta and pass into an excited state. When they return to their normal state, they emit light themselves – they fluoresce. This process is specific to each substance, so it allows you to judge its structure.

To facilitate observations in biological and medical research, substances with pronounced fluorescence properties – fluorophores - are additionally used. They selectively bind to various cellular structures, which themselves glow weakly.

Despite the relatively low resolution, fluorescence microscopy remains an important research method, since it allows analyzing processes in living cells down to the molecular level.

The number of simultaneously used fluorophores imposed restrictions on the number of cell structures labeled during one experiment. Usually, the number of different color marks visible in ultraviolet light did not exceed six.

Attaching fluorophores to the nanorods (image: Wyss Institute)

"DNA barcode" allows you to create a much larger number of coding color sequences. Nanorods created by self-assembly of DNA are used as a carrier of labels. The distance between the labels reaches 40 nm, which can be considered an example of super-dense coding.

"DNA barcode" – 216 combinations of triads of six fluorophores (image: Wyss Institute)

A sequence of three labels of six colors gives 216 combinations, and this is not the limit. Due to the expanded color labeling in one experiment, it becomes possible to simultaneously analyze more data and take into account previously unnoticed relationships.

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