Photoacoustic contrast imaging of biological tissues with nanodiamonds fabricated for high near-infrared absorbance

Abstract

Abstract. Radiation-damaged nanodiamonds (DNDs) are potentially ideal optical contrast agents for photoacoustic (PA) imaging in biological tissues due to their low toxicity and high optical absorbance. PA imaging contrast agents have been limited to quantum dots and gold particles, since most existing carbon-based nanoparticles, including fluorescent nanodiamonds, do not have sufficient optical absorption in the near-infrared (NIR) range. A new DND by He þ ion beam irradiation with very high NIR absorption was synthesized. These DNDs produced a 71-fold higher PA signal on a molar basis than similarly dimensioned gold nanorods, and 7.1 fmol of DNDs injected into rodents could be clearly imaged 3 mm below the skin surface with PA signal enhancement of 567% using an 820-nm laser wavelength.

Recent Developments and Applications of Nanodiamonds as Versatile Bioimaging Agents

“…The study highlights the potential of developing FNDs as dual imaging contrast agents for combined fluorescence and photoacoustic imaging, if photocleavable linkers are used to conjugate FNDs with GNPs. In a separate study, Zhang et al 71 applied a new type of NDs fabricated with high optical absorbance in the near infrared region (700 -1000 nm) as a contrast agent for PA imaging. The fabrication involved extensive radiation damage and thus the particles (named DNDs) could contain a high-density ensemble (up to 3000 ppm) of V 0 (or GRI) defect centers in the crystal matrix.…”

The Effect of Laser Power on Photothermoacoustic Imaging of Blood Containing Gold Nanoparticles and Deoxygenation using a Frequency-Domain Phased Array Probe: An In-vitro Assay

“…The medical imaging modality employed for detection of malignant tumors in organs such as breast cancer should provide high-specificity to cancer and high resolution for early In situ detection [18]. Since, the main strength of PAI is its ability to obtain functional, anatomical and molecular information in real-time with a high resolution at clinically relevant depths, therefore either endogenous biomolecules such as hemoglobin, melanin and carotonoids or exogenous contrast agents such as indocyanine green [19], nanoparticles [20,21], nanoshells [22,23], nanorods [24,25], nanocages [26,27], and nanodiamonds [28] can be employed for image enhancement. However, as it will be discussed, for in vivo applications the nanostructures must be active targeted by conjugating them with suitable moieties e.g., antibodies, peptides or folates to prevent from protein adsorption and aggregation.…”

In vivophotoacoustic imaging of breast cancer tumor with HER2-targeted nanodiamonds

“…28 Non-fluorescent nanodiamonds with ~70 nm in diameter employed as a PA imaging agent was firstly proposed in our earlier publication. 29 Since a low fluorescence quantum yield results in more efficient PA signal generation, nanodiamonds shown ~70 times stronger PA signals than gold nanorods on a particle molar basis.…”