Bio-sensing with NV-centers in diamond

Color centers in diamond, most frequently the negatively charged nitrogen vacancy (NV − ) center, have demonstrated their applicability as optically actuated quantum sensors of e.g. temperature, magnetic field, or electrical fields. Further, the promise of NV − as a nano- or microscale nuclear magnetic resonance spectrometer has created attention. In this review, the focus is on sensing capabilities offered by NV-centers in particular for investigations of biological systems. Two different approaches, using bulk diamond or nanodiamonds with NV-centers, the so-called fluorescent nanodiamonds, respectively, is discussed, with each their strengths and challenges.