Monitoring of Metabolic Activity in Living Cells

Free radicals are tiny, highly reactive molecules or atoms that play key roles in the body, such as helping immune cells fight infections, but they can also be created from oxidative stress in cells, contributing to aging and diseases such as sepsis, arthritis, infertility and cancer. Because they exist only for very short times and react quickly, they are extremely hard to measure inside living cells using current methods. This makes it difficult to study how cells work at the small (subcellular) level.

A diamond‑based quantum sensor uses fluorescent nanodiamonds with nitrogen‑vacancy centres to detect magnetic signals from free radicals at nanomolar levels inside single cells in real time. In this method, called relaxometry, fluorescent nanodiamonds (FNDs) are connected to single mitochondria inside living cells. These diamonds can pick up the weak magnetic signals from the free radicals and turn them into light signals, making it possible to “see” the activity happening inside the mitochondria.

This quantum sensing approach allows for the monitoring of the metabolic activity of individual mitochondria in real-time. It enables precise mapping of oxidative stress dynamics, which opens the door to better understanding how cells function, how diseases develop, and how we might design more precise and targeted treatments in the future.