Fluorescent Nanodiamonds for Multiplexed Imaging and Diagnostics - Summary
Under this project, a means for the creation of fluorescent nanodiamond (FND) of multiple colors for multiplexed
detection in biological assays will be developed. Fluorescent imaging is an ever increasingly important technique
in biomedical research with a growing demand for fluorescent labels which are non-toxic, bright, photostable,
and which can be easily derivatized with targeting ligands. Nano-sized crystallographic diamond can be made
to contain fluorescent color centers by the appropriate processing of atomic lattice constituents to create
complexes of impurity atoms and lattice vacancies. Because these created fluorescent centers are embedded
in the diamond lattice, they are not susceptible to photobleaching as occurs with other conventional fluorophores.
Although red FND has been commercially developed, there have been no means to create bright reproducible
FND of other colors. By adopting the method of rapid thermal annealing and using synthetic diamond particles
with reproducible nitrogen content and positioning within crystallographic lattice, processing conditions may be
achieved to controllably produce color centers unattainable in a conventional thermal annealing process. The
colors to be produced will be blue, green, and red, benchmarked for brightness against current commercial
organic fluorophors. Each color may be excited by the same ultraviolet wavelength, thereby improving the
workflow of multi-signal labeling. Alternatively, all colors are accessible via two-photon absorption of wavelengths
from the range 800-1080 nm, allowing for increased tissue penetration and reduced background fluorescence.
Due to exceptionally high biological compatibility and unique optical properties, multiplexing via FND has broad
applications in immunological assays, flow cytometry, correlative microscopy using multiple fiducial markers,
labels for tissue scaffold engineering, and for tagging stem cells in regenerative medicine. In this project,
specific utility will be demonstrated using recently developed targeting ligands specific either for vascular
endothelial growth factor receptors 1 or 2, which represent potential targets for anti-angiogenic anti-cancer
therapies. The outcome of this research will be the demonstration of non-toxic, infinitely photostable fluorescent
diamond particles for use in cancer diagnostics.
