The Red and Blue Light Show

Chemistry researchers provide new insights into molecular imaging.

Changing coloured lights are not just for Christmas trees or concert light shows. In cellular and molecular imagining, changing colours are used to understand reactions. The leading method of cellular and molecular imaging is small-molecule-based fluorescent probes. Fluorescent probes are used to study biological samples and can provide information on cell health, disease status and response to external stimuli, like drugs and alcohol. These are molecules that absorb a specific wavelength of light and emit a different, typically longer, wavelength – a process known as fluorescence. 

A classic fluorescent chemosensor, an injectable dye that binds to other molecules and creates a desired response, turns from red to blue when it binds to the appropriate receptor. There has been significant research conducted on fluorescent chemosensors for cellular identification of biologically relevant molecules. However, there is still a significant challenge to develop probes to identify a specific compound of interest and then decode the process behind detecting it in the microenvironment of the cell.

Revising chemosensing mechanisms

University of Guelph Chemistry professors Drs. Richard Manderville and Aicheng Chen, Molecular and Cellular Biology professor Dr. Terry Van Raay, Facility and Nuclear Magnetic Resonance Centre Facility Manager Dr. Sameer Al-Abdul-Wahid together with graduate students Ryan Johnson, Joshua van der Zalm and Ian Bell collaborated to revise the chemosensing mechanism by a classic chemosensor used for the detection of reactive sulfur species. Reactive sulfur species are a group of sulfur-based molecules. The original theory behind chemosensing suggested that the chemosensor turned from red to blue in the presence of reactive sulfur species in the powerhouse (or mitochondria) of cells. The Guelph research team found that reactive sulfur species was not responsible for the observed colour change. Instead, the chemosensor was reacting directly with the reactive oxygen species, hydrogen peroxide, and that the chemosensor serves as a direct detection method for the presence of hydrogen peroxide in cells, which can damage the cells basic building blocks (proteins, DNA, lipids). 

From red to blue