We can now watch cancer cells 'breathe' in real-time without using a single drop of dye.

To see what's happening inside a cell, doctors usually have to inject fluorescent dyes, which can be toxic or change how the cell behaves. This new microscope uses two-photon light to detect the cell's own natural chemicals at incredibly low levels. It is the first time we've been able to see a cell's metabolism and its response to chemotherapy this clearly in its natural state. This means doctors could test how a patient's cancer responds to different drugs in hours instead of weeks. It is a literal window into the life and death of a cell.