Fluorescent nanodiamonds (FNDs) are biocompatible particles with indefinite photo-stability that have emerged as promising bioimaging probes. FNDs with negatively charged nitrogen-vacancy (NV-) centers are superior imaging probes because they do not photobleach or blink, have a high quantum yield, large Stokes’ shift, long fluorescence lifetimes, and fluorescence emission that can be modulated by magnetic fields to improve signal:noise >100x. Their broad fluorescence emission in the near infrared region (lmax = 685 nm) can penetrate into the tissue with limited background signal from autofluorescence.
Results from the development of FNDs with specific terminal groups and bioconjugation chemistries for various in vitro and in vivo imaging applications will be presented. Bikanta’s probes (1) remain monodisperse and stable in liquid suspension unlike conventional nanodiamonds that aggregate into clusters, and (2) rather than having the typical unreactive surface, can be tightly bound to any targeting agent (e.g. aptamers, antibodies) and can therefore be tailored to detect specific diseases. Bikanta is also designing novel imaging instrumentation to improve detection capabilities. Nanodiamonds are exquisitely sensitive to magnetic fields and this sensitivity reduces background noise to improve visualization deeper into the body. Early results have already improved signal 100-fold over current methods.
Bikanta illustrates the unique features and potential uses of FNDs from single molecule to in vivo imaging with several applications: (1) high spatial and temporal resolution 3-D tracking over extended periods of time, (2) as stable fiducial markers for ultra high resolution microscopy across multiple wavelengths, (3) cell and generation tracking, (4) immunohistochemistry labeling, (5) tumor uptake, and (6) wide-field background-free imaging through magnetic modulation to image lymph node through tissue.