Researchers at Okayama University in Japan have achieved a major breakthrough by developing nanodiamond sensors with the potential to revolutionize quantum sensing and bioimaging applications. These advanced sensors could enable highly detailed and accurate images of biological systems, significantly enhancing disease detection and treatment. Additionally, they could allow scientists to detect minute atomic and molecular changes that conventional sensors cannot identify, offering new possibilities for scientific exploration.

“Both quantum sensing and bioimaging have the potential to transform healthcare, technology, and environmental management, improving the quality of life and offering sustainable solutions to future challenges,” said Masazumi Fujiwara, an associate professor at Okayama University and one of the researchers involved in the study.

Both quantum sensing and bioimaging rely on the unique quantum properties of particles, such as spin state, entanglement, and superposition. Nanodiamonds containing nitrogen-vacancy (NV) centers are particularly promising for these applications due to their exceptional sensitivity to tiny changes in electrical, thermal, and magnetic behavior.

Nanodiamonds are formed when nitrogen atoms replace carbon atoms in the diamond lattice, creating small vacancies. These NV centers endow the nanodiamonds with remarkable properties, including the ability to glow under certain light conditions and detect subtle changes in magnetic and electric fields, making them ideal candidates for quantum sensors.

While the potential of nanodiamonds with NV centers has been widely recognized, producing high-quality versions has proven to be challenging. Past efforts often led to diamonds with impurities and unstable spin states. However, Fujiwara and his team overcame this obstacle with a controlled NV center creation technique.

The researchers began by growing a diamond crystal composed of 99.99% carbon-12 atoms. They then introduced nitrogen at concentrations ranging from 30 to 60 parts per million into the crystal. Since not all nitrogen atoms form vacancies, the final NV center concentration was around one part per million. The team then broke the crystal into tiny fragments, mixed them into water, and dropped the mixture onto glass coverslips with grid patterns, resulting in numerous nanodiamonds measuring approximately 277 nanometers, each with negatively charged NV centers at a concentration of 0.6 to 1.3 parts per million.

The nanodiamonds developed by the team displayed strong fluorescence, achieving a photon count rate of 1500 kHz, making them highly suitable for bioimaging applications. They also demonstrated enhanced spin properties compared to larger commercially available nanodiamonds, further improving their potential for quantum sensing.

To fully explore their capabilities, the researchers utilized optically detected magnetic resonance (ODMR), a method that combines light and microwaves to study the magnetic properties of materials. ODMR allows scientists to investigate the spin states of nanodiamonds by shining light on them and applying microwaves to observe how the material reacts. This technique helps detect subtle magnetic signals, enabling a better understanding of a material’s properties.

As part of their testing, the researchers introduced the nanodiamonds into HeLa cells (widely used human cells in lab research) and employed ODMR to examine the spin states. The nanodiamonds successfully detected slight temperature changes, which are typically difficult to measure with existing technologies.

This breakthrough in nanodiamond sensor technology opens the door to groundbreaking advancements in both quantum sensing and bioimaging, offering potential applications in healthcare, scientific research, and beyond.

By Impact Lab