The latest Lunchtime Seminar from the Institute for Molecular Science and Engineering looked at utilising light to analyse and control biology.

Professor Thomas Knopfel (Professor in the Department of Medicine, and Chair of Optogenetics and Circuit Neurosciences) and Professor Matt Fuchter (Professor in the Department of Chemistry) presented two perspectives on using light to understand and control biology during their recent Institute for Molecular Science and Engineering (IMSE) Lunchtime Seminar.

Using light to monitor sleep

Electrical signals are vitally important to key functions within our bodies. In the heart electrical signals coordinate the heartbeat, and in the brain they generate perception, cognition and emotions. Such signals are controlled by the voltage across plasma membranes. 

Essentially the brain is an electrical machine - thoughts are electrical signals. Professor Thomas Knopfel Professor in the Department of Medicine, and Chair of Optogenetics and Circuit Neurosciences

In his seminar, Professor Knopfel outlined the development, current state of the art, and prospects of emerging genetically encoded voltage indicators (GEVIs). These indicators are proteins that can respond to changes in the voltage across a membrane by using voltage-sensitive dyes dissolved in the membrane. This allows electrical activity in the brain to be monitored using only light. 

Such indicators have uses in monitoring brain activity, in particular, measuring corticol waves during sleep. Corticol waves are closely associated with memory consolidation, and their understanding can help patients to have quicker recovery times after anaesthesia. Other applications include optogenetics - using light to control cells in genetically modified tissues that are light-sensitive. Non-invasive measurements have already been carried out on living animals, and have been shown to permeate through thin bone.

The same techniques can also be used for cardiac studies to understand the working of the heart, and how signals are transmitted across scar tissue.

High performance molecular photoswitches 

In his seminar Professor Matt Fuchter introduced molecular photo-switching, the ability to switch a molecule between at least two different states with stimuli, for example, two different wavelengths of light.

It is possible to control the channels responsible for pain and itching, and to start and stop the heart beating using light. Professor Mattew Fuchter Professor of Chemistry

One of its most promising applications is in photopharmacology, where the delivery of a particular drug could be activated when it reached the target tissue using light, reducing side effects. Currently the best known example is in photodynamic therapy; a dye-sensitised destruction of cancer tissue via singlet oxygen. But this usually uses porphyrins and relies on having oxygen present, therefore limiting its use.

Currently Professor Fuchter and his team of researchers are working on a new class of photoswitch, arylazopyrazoles, which offer quantitative photoswitching and increased stability, even in water or biological systems. By tuning the properties of the molecule through molecular design, Professor Fuchter's group can explore their structure-property relationships. For example, making molecules more twisted results in them absorbing more light. This allows for the dosage of a particular drug to vary according to intensity of light.