Researchers from Japan have developed biocompatible molecular quantum nanosensors (MoQNs) that can measure temperature and detect chemical radicals inside living cells with unprecedented precision.

The development comes from researchers at the National Institute for Quantum Science and Technology (QST) and the University of Tokyo in collaboration with Kyushu University. 

“The study demonstrates that these nanosensors enable absolute temperature measurements with subcellular spatial resolution and detect radical-related spin signals in both the cytoplasm and nucleus of living cancer cells,” the researchers noted.

The precision problem

Until now, scientists have used hard quantum sensors, such as nanodiamonds, which rely on random defects in a crystal lattice. This means no two sensors are exactly alike, leading to noisy data and inconsistent results. These suffered from inconsistent material quality and poor biocompatibility. 

To address the long-standing difficulty of precisely mapping the internal environments of living cells, researchers designed these Molecular Quantum Nanosensors. This new platform uses pentacene molecular spin qubits protected within organic nanocrystals. 

Every MoQN is identical. This molecular-level consistency enables absolute temperature readings that don’t fluctuate due to the sensor’s inherent flaws.

Coated with a specialized surfactant to ensure cell safety, these sensors achieve molecular uniformity, function reliably under physiological conditions, and overcome the limitations of previous quantum sensing technologies.

Furthermore, rigorous testing confirmed these sensors are entirely biocompatible, as they enter cells without disrupting membrane integrity, metabolism, or natural growth cycles.

Detecting chemical radicals

The testing showed that MoQNs maintain full quantum functionality in the cellular environment, performing complex tasks such as spin-echo measurements and relaxometry. 

Using deuterated pentacene (dMoQNs) to fine-tune molecular interactions, hyper-precise temperature readings were obtained, revealing that cells are warmer than their surroundings. 

Most notably, the team successfully mapped the nucleus, uncovering distinct “hot spots” and thermal variations at specific intranuclear positions, proving these sensors can provide a detailed thermal map of a cell’s most vital organelles.

In simpler terms, they found that different parts of the nucleus have different temperatures, a discovery that could redefine our understanding of how DNA behaves and how heat drives cellular reactions.

Beyond heat, the MoQNs act as reporters for the cell’s chemical state. It can detect signals associated with radical activity within a cell. Life is driven by chemical reactions, many of which involve “radicals”—highly reactive molecules that can cause damage or signal stress. 

Furthermore, researchers proved that these sensors can monitor “oxidative stress” by tracking changes in spin behavior across both the cytoplasm and the nucleus. 

Ultimately, this versatility transforms the MoQN into a multi-purpose quantum platform that can report on a cell’s internal chemistry and health just as easily as its temperature.

“This work shows that MoQNs can operate directly inside living cells while maintaining the precision needed for absolute thermometry,” said Dr. Ishiwata, Team Leader of the Quantum Bioengineering Team at QST. “We believe this opens a new route toward quantitative quantum measurement of intracellular environments.” 

These new sensors are easy to customize, safe for living tissue, and provide clear data in real-world conditions. This development could pave the way for super-precise thermometers and chemical detectors that work at a microscopic level. 

Eventually, this technology could transform medicine by allowing doctors and scientists to monitor the smallest inner workings of our cells with quantum accuracy.

The findings were published in the journal Science Advances on April 29, 2026.