2, Duke University, Durham, North Carolina, United States
3, Sibtech, Inc., Brookfield, Connecticut, United States
4, Creative Scientist, Raleigh, North Carolina, United States
The utility of fluorescent nanodiamonds (FNDs) for in vivo bio-imaging was investigated. Fluorescence of ND as a function of size and concentration was measured via an in vivo imaging system to help determine optimal sizes for in vivo detection. This baseline analysis determines a threshold as to the expected imaging signal from whole-body imaging systems. ND was then administered via tail vain injection to nude BALB/c mice induced with a 4T1 mammary carcinoma to determine particle biodistribution via both whole-body imaging and supplemental ex vivo analysis. Due to ND stability against acidic conditions, tissues were digested and analyzed to provide quasi-quantitative assessment of tissue loading. In post-analysis microscopy of tissue, the unique spectral shape of nitrogen-vacancy induced fluorescence provided unambiguous determination of ND translocation to specific organs. Though particle sizes down to 60 nm are detectable via whole-body imaging systems if sufficiently concentrated, sizes above 170 nm are necessary to produce significant contrast in vivo after intravenous injection. These results are then placed in the context of FND for whole-body imaging and related applications.