School of Molecular Biosciences

The electromagnetic spectrum is made up of visible light (red, orange, yellow, green, blue, indigo & violet) and invisible light (e.g. ultraviolet, x-rays, infrared). Both visible and invisible light travel in waves that have different lengths and energy levels. For example, red light has a longer wavelength but less energy than violet light.

Fluorescence is the emission of light by a substance, object (gemstones), plant or animal (jellyfish, corals) that has absorbed light of a particular wavelength, and then releases light of a different wavelength. In most cases, fluorescent objects absorb light of a shorter wavelength and emit light at a longer wavelength. This is because the emitted light has less energy than the one that was absorbed. There are, however, exceptions to this rule.

Fluorescence is a useful concept for scientific research and has become widely used in a variety of research areas such as cell biology, physiology and chemistry. Most commonly, fluorescent dyes and labels can be used to let scientists ‘see’ different molecules, structures or cell types.

We label one of the interacting molecules with a bioluminescent protein which emits high energy light. The energy from this light is then harnessed to “switch on” a fluorescent protein attached to a second molecule. The clever thing about this technique is that the energy transfer only occurs if the two molecules are interacting close together. We can determine just how close the molecules get by measuring the fluorescent light released from the second molecule.

In our activities, you can see principles of BRET in action. High energy light from your UV torch will “switch on” the fluorescence of invisible ink as you identify your target, find your medicinal “hit”, and improve your medicine!