Scientists at the University of Bath have developed a fluorescent tool for detecting reactive oxygen species based on a chemical found in mushrooms. Reactive oxygen species (ROS), such as free radicals and peroxides, are produced in cells under oxidative stress. While present in healthy cells in small amounts, excessive ROS in cells are damaging and can lead to cancer and neurodegenerative diseases such as Alzheimer’s. The scientists at Bath, collaborating with researchers in South Korea, have developed a new probe that biologists studying these diseases can use to see changes in cells under the microscope, helping them to understand the fundamental biological processes involving ROS. To achieve this goal, the researchers created a new family of molecules called AzuFluor, based on azulene, a bright blue chemical found in the mushroom Lactarius indigo. It fluoresces when it comes into contact with ROS in a one-way reaction, detecting tiny amounts of these reactive oxygen species. While most fluorescent probes absorb a single photon, AzuFluor absorbs two photons, meaning that two lower energy photons can be used to produce the same level of fluorescence. Using shorter wavelengths of light in infrared range means that the light can penetrate tissues deeper without causing damage to the cells. “AzuFluor is a much smaller molecule and simpler to make than other two-photon fluorophores. Its small size makes it easy to diffuse and transport into the cells,” said Simon Lewis, senior lecturer in the Centre for Sustainable and Circular Technologies (CSCT) at the University of Bath. “We aim to make a family of these fluorophores that can be used in a range of cell imaging applications.” According to Professor Tony James, also of CSCT, the research has wide-ranging potential applications in cell biology and the pharmaceutical industry and is an example of what can be achieved through international collaboration. The research was published in JACS Spotlight (www.doi.org/10.1021/jacs.9b09813).