pH Nano-sensing in Biology Using Electronic Spins in Diamond

The negatively charged nitrogen-vacancy (NV-) center in diamond has emerged as a potential candidate in different scientific applications due to its unique quantum properties and compatibility with room temperature. Research has indicated that the relaxation time of the electronic spins in NV centers is influenced by the surrounding pH, specifically between pH 3 and pH 7. This finding highlights the ideal fit of measurement as reliable nanoscale sensors for real-time monitoring of pH in biological systems, such as living cells. Based on different published work, we have successfully assembled and tested a tabletop single pixel confocal microscope to measure lifetime in aqueous solutions. By employing more advanced quantum sensing techniques, we anticipate that measuring spin density created by reactive oxygen species and other free radicals in cells can be achieved.