Quantum thermometer using nanodiamonds senses a fever in live, microscopic animals

Get diamonds, take the temperature.

The optical microscope, often referred to as the “light optical microscope,” often used for analysis in biology, uses visible light and a system of lenses to magnify images of small samples. On the other hand, a fluorescence microscope uses a much higher intensity light source that excites a fluorescent species in a sample of interest. The fluorescence microscope is an enhanced version of the optical microscope with various fluorescent biomarkers.

Recent advancements in such fluorescence microscopy have allowed for live imaging of the details of a structure, and through this, obtaining various physiological parameters in these structures, such as pH, reactive oxygen species, and temperature.

Real-time temperature monitoring inside living organisms provides a direct measure of their biological activities. However, it is challenging to reduce the size of biocompatible thermometers down to submicrometer, despite their potential applications for the thermal imaging of sub tissue structures with single-cell resolution.

In collaboration with other international partners, scientists from the Osaka City University have developed a reliable and precise microscope-based thermometer that works in live, microscopic animals based on quantum technology, specifically, detecting temperature-dependent properties of quantum spins in fluorescent nanodiamonds.

Using this quantum nanothermometer based on optically accessible electron spins in nanodiamonds, scientists demonstrated real-time temperature monitoring inside Caenorhabditis elegans worms.

To do so, they decorated the surface of the nanodiamonds with polymer structures and injected them into C. elegans nematode worms. They aimed to determine the base “healthy” temperature of the worms.

Once inside, the nanodiamonds moved quickly, but the team’s novel quantum thermometry algorithm successfully tracked them and steadily measured the temperature. Fever was induced within the worms by stimulating their mitochondria with pharmacological treatment. The team’s quantum thermometer successfully observed a temperature increase in the worms.

Masazumi Fujiwara, a lecturer at the Department of Science at Osaka City University, said“It was fascinating to see quantum technology work so well in live animals, and I never imagined the temperature of tiny worms less than 1 mm in size could deviate from the norm and develop into a fever. Our results are an important milestone that will guide the future direction of quantum sensing as it shows how it contributes to biology.”

Journal Reference:
  1. Masazumi Fujiwara et al. Real-time nanodiamond thermometry probing in vivo thermogenic responses. DOI: 10.1126/sciadv.aba9636

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