Quantum view of brain chemistry

French researchers have used a molecular scale imaging tool to track the movements of individual receptors within the membranes of cells, something that cannot be accomplished using conventional approaches such as fluorescent dyes or polymer spheres.

The study, published in Science​ focuses on the use of quantum dots - nanoscale crystals of semiconductor material that fluoresce when hit by a light source such as a laser. The researchers used these quantum dots to track the movements of individual glycine receptor molecules in living cell membranes over a number of minutes, something that has not been achieved to date within a single experiment.

The approach provides a means of studying processes that may eventually lead to new drug leads for treating neurological disorders, said the scientists, from the Ecole Normale Superieure and the Universite Pierre et Marie Curie in Paris.

Older imaging tools such as fluorescent dyes or polymer spheres are either too unstable or too big to effectively perform single-molecule tracking, the scientists wrote. In contrast, the quantum dot approach produced photo resolutions up to eight times more detailed than the older imaging tools, they added.

The quantum dots used in the study were developed by US company Quantum Dot​, based in Hayward, California.

The quantum dot conjugates also proved to be "almost an order of magnitude" brighter than fluorescent dyes, and could be observed for as long as 40 minutes compared to about 5 seconds for the dyes, the French scientists reported. Length of observation time is critical to studying cellular processes, which change rapidly over a span of several minutes.

The glycine receptors in the current report are the main inhibitory neurotransmitter in the human spinal cord and brain stem, and a greater understanding of their function could lead to the development of new drugs to treat diseases such as epilepsy and depression.