Preparation and Characterization of Ion-Irradiated Nanodiamonds as Photoacoustic Contrast Agents.
Highly radiation-damaged or irradiated nanodiamonds (INDs) are a new type of nanomaterial developed recently as a potential photoacoustic (PA) contrast agent for deep-tissue imaging. This work characterized in detail the photophysical properties of these materials prepared by ion irradiation of natural diamond powders using various spectroscopic methods. For 40-nm NDs irradiated with 40-keV He+ at a dose of 3 x 10(15) ions/cm2, an average molar extinction coefficient of 4.2 M-1 cm-1 per carbon atom was measured at 1064 nm. Compared with gold nanorods of similar dimensions (10 nm x 67 nm), the INDs have a substantially smaller (by > 4 orders of magnitude) molar extinction coefficient per particle. However, the deficit is readily compensated by the much higher thermal stability, stronger hydrophilic interaction with water, and a lower nanobubble formation threshold (~30 mJ/cm2) of the sp3-carbon-based nanomaterial. No sign of photodamage was detected after high-energy (>100 mJ/cm2) illumination of the INDs for hours. Cell viability assays at the IND concentration of up to 100 µg/mL showed that the nanomaterial is non-cytotoxic and potentially useful for long-term PA bioimaging applications.
Chia-Yi
CY
Fang
Cheng-Chun
CC
Chang
Chung-Yuan
CY
Mou
Huan-Cheng
HC
Chang
D002470:Cell Survival / Q000187:drug effects; D003287:Contrast Media / Q000138:chemical synthesis* / Q000633:toxicity; D003952:Diagnostic Imaging / Q000379:methods*; D006367:HeLa Cells; D020450:Heavy Ions; D006801:Humans; D008422:Materials Testing; D058612:Nanodiamonds / Q000737:chemistry* / Q000633:toxicity; D061088:Photoacoustic Techniques / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D003287:Contrast Media; D058612:Nanodiamonds