Webb's research helps medical, biomedical, and biological science researchers to study diseases such as Alzheimer's, colitis, cancer, and sun damage to skin. His work helps to untangle mysteries such as the mechanisms that underlie immunological and hormonal responses, signaling by neural modulators such as serotonin in the nervous system and the brain, and transmembrane signaling. Now, they conduct many optical experiments in which they can look at one molecule at a time. Here is how it works. They focus a laser beam into a tiny focal volume, less than a cubic micron, on molecules in solution or in living cells.
Molecules wander through the focal volume as they diffuse.
The researchers can detect these molecules because they fluoresce when they absorb the laser light. The molecules can absorb light in this tiny focal volume and emit bright fluorescence like a Day-Glo poster. It happens in a nanosecond instead of a half-hour. We can detect up to a million photons by exposing a single molecule. We can do many measurements with only a few hundred photons.