Bioconjugated Fluorescent Nanodiamond
Time-lapse of blood clots specifically labeled with fluorescent nanodiamond (top) or phycoerythrin (PE) (bottom). PE quickly degrades, while the fluorescent nanodiamond signal remains constant.
We provide nanodiamonds with nitrogen-vacancy (NV) centers and H3 ( NVN) centers (Figure 1). Protein, antibody, biologically active organic molecules, and custom functionalizations for different particle sizes are possible.
Biofunctionalized Fluorescent Nanodiamond Technical Info
Bio-functionalized fluorescent nanodiamonds (FNDs) offer an infinitely photostable label for fluorescent and multiphoton microscopy for cellular and in vivo tracking and long-term observation of biological processes. We provide nanodiamonds with nitrogen-vacancy (NV) centers and H3 ( NVN) centers (Figure 1). Protein, antibody, biologically active organic molecules, and custom functionalizations for different particle sizes are possible.
Novel particles are also available (only at Adamas) with a combination of NV and NVN centers within a single particle, providing the capability for ratiometric calibration of the fluorescence (monitoring ratio between intensities of emission in the green and red spectral ranges). This capability helps in tracking particles even with high background fluorescence.
Biofunctionalized FNDs containing negatively charged NV centers are increasingly used as powerful sensors for surrounding spins due to uniquely coupled magneto-optical properties of the NV center. The intensity of FND fluorescence depends on the NV centers electronic states, which in turn depends on external electromagnetic fields.
Spectral Characteristics of NV- and NVN Centers
NV Emission Spectra as A Function of Particle Size
The brightness of particles depends on the particle size. The larger the particle, the higher the brightness due to the larger number of color centers that can be accommodated by larger particle volumes. If small size is necessary for your work, then the 40nm particles offer the best compromise between brightness and size. For first time users, it is recommended to start with larger particle sizes (~ 100 nm and above) to determine if fluorescent nanodiamonds (FNDs) will provide the necessary contrast in your application.
Emission spectra for FNDs contain characteristic Zero Phonon Lines ZPLs for the NV center with neutral charge (NV0) and negatively charged NV- centers located at 575 nm and 638 nm denoted by green arrows in Figure 3, respectively. As the particle size decreases, the ZPL signature tends to decrease due to the reduced number of emitters per particle, which decreases approximately volumetrically with particle volume. Because particles are produced by milling/crushing larger particles, induced lattice damage can significantly impact the quality of NV centers and the resultant spectroscopic quality.
Electron paramagnetic resonance EPR studies were performed to evaluate the concentration of NV- centers in the particles. For the 40 nm material, the NV- concentration was determined to be on the order of 1 ppm and ~ 3 ppm for 100-140 nm particles, which equates to approximately ~300 centers per 100 nm particle and ~800 centers per 140 nm particle. In general, a particle volume ratio related dependence on the number of centers per particle is observed with respect to size.
Fluorescence Microscopy with FND
The brightness of aggregates of 20nm particles is high enough to be detected within cells after internalization in a confocal setup (Figure 4).
In Vivo Imaging with FND
The large size range high brightness particles have been used extensively in in vivo and in vitro studies. The particles have been successfully conjugated with human vascular endothelial growth factor (VEGf) and tumor targeting demonstrated.[1]
170 nm particles have also been used for whole body in vivo imaging in mice.[2] Intravenous injection into mice with non-targeting FNDs showed spleen and liver accumulation over time Figure 5). No observed toxicity was detected over a 24h period. There is more information on the website . Ex vivo digestion analysis of the spleen and liver tissue confirmed the presence of diamond (Figure 6).
