Silicon Vacancy in Boron-Doped Nanodiamonds for Optical Temperature Sensing

Abstract

Boron-doped nanodiamonds (BNDs) have recently shown a promising potential in hyperthermia and thermoablation therapy, especially in heating tumor cells. To remotely monitor eigen temperature during such operations, diamond color centers have shown a sensitive optical temperature sensing. Nitrogen-vacancy (NV) color center in diamonds have shown the best sensitivity in nanothermometry; however, spin manipulation of the NV center with green laser and microwave-frequency excitations is still a huge challenge for biological applications. Silicon-vacancy (SiV) color center in nano/bulk diamonds has shown a great potential to be a good replacement of the NV center in diamond as it can be excited and detected within the biological transparency window and its thermometry operations depends only on its zero-phonon line (ZPL) shift as a function of temperature changes. In this work, BNDs were carefully etched on smooth diamond nanocrystals’ sharp edges and implanted with silicon for optical temperature sensing. Optical temperature sensing using SiV color centers in BNDs was performed over a small range of temperature within the biological temperature window (296–308 K) with an excellent sensitivity of 0.2 K in 10 s integration time. These results indicate that there are likely to be better application of more biocompatible BNDs in hyperthermia and thermoablation therapy using a biocompatible diamond color center.

Multifunctional Core/Shell Diamond Nanoparticles Combining Unique Thermal and Light Properties for Future Biological Applications

“…A main drive for the improvement of local hyperthermia techniques is the promise of effective, selective, and controlled heating. Due to the high absorption coefficient in the near-infrared region of the spectrum, diamond nanoparticles heavily doped with boron are very promising for photothermal therapy [3][4][5]. Additional advantages of the use of diamond nanoparticles as local photoinduced heaters are diamonds' exceptionally high thermal conductivity, biocompatibility, and ease of bioconjugation thanks to well-developed surface functionalization techniques [6].…”

“…The most attractive color centers in diamond nanoparticles suitable for nanothermometry are the family of centers based on IV-group interstitial atoms (Si, Ge, Sn, and Pb) positioned between two vacancies in the diamond lattice [19]. Diamond nanocrystals with silicon vacancy (SiV) color centers, whose intense and narrow ZPL at ∼738 nm falls within the transparency region of biological tissues, are ideally suited for bioimaging, which is necessary for visualizing targets for hyperthermia therapy and local nanothermometry [5,12,[15][16][17][18][19][20][21].…”

“…The idea to combine the advantages of the diamond nanocrystals doped by the different atoms in order to create a novel multifunctional heterostructure for efficient local photoinduced hyperthermia therapy, whilst also controlling the temperature of the tissue and labeling it with a fluorescent marker, looks very attractive [22]. At least two attempts to synthesize diamond nanocrystals doped with boron, silicon, and germanium are known [5,23]. In the first case [5], commercially available boron-doped nanodiamonds (BNDs) with an average size of 100 nm were implanted with silicon for optical temperature sensing.…”

“…At least two attempts to synthesize diamond nanocrystals doped with boron, silicon, and germanium are known [5,23]. In the first case [5], commercially available boron-doped nanodiamonds (BNDs) with an average size of 100 nm were implanted with silicon for optical temperature sensing. In the second case [23], BNDs were synthesized using the hot filament chemical vapor deposition (HFCVD) technique with GeV and SiV color centers embedded during the growth process.…”