Spying on a Conversation between Biomolecules with a Quantum Diamond Sensor

What is it about?

Life depends on countless interactions between biomolecules. Studying them one at a time can reveal subtle details that are often lost when observing billions at once. Current single-molecule techniques—such as those based on fluorescence or ionic currents—often face limitations like signal fading or environmental interference. A research team from the University of Science and Technology of China has developed a fundamentally different approach. Their method makes use of spin signals, an intrinsic magnetic property of many biomolecules, or one that can be introduced through labeling. They employ tiny defects in diamonds known as nitrogen-vacancy (NV) centers, which act as highly sensitive quantum sensors capable of detecting magnetic signals from spin-labeled proteins. When a labeled protein binds near the sensor, it alters the relaxation behavior of the NV center’s spin—a change that can be precisely measured. This detection strategy is enabled by two key innovations: one is a nanogel layer that optimizes the biomolecule–sensor interface, and the other is a novel quantum signal analysis method that significantly improves detection sensitivity.

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Photo by Rafael Garcin on Unsplash

Photo by Rafael Garcin on Unsplash

Why is it important?

This study reports the first observation of biomolecular interactions at the single-molecule level through their spin properties, establishing a new detection modality that complements existing optical and electrical methods. The platform provides a stable, non-bleaching way to monitor molecular interactions, free from the high background noise often encountered in biological samples. This advance helps transition quantum sensing from a conceptual tool to a practical one in the life sciences.

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