Characterization and application of single fluorescent nanodiamonds as cellular biomarkers.
Type Ib diamonds emit bright fluorescence at 550-800 nm from nitrogen-vacancy point defects, (N-V)(0) and (N-V)(-), produced by high-energy ion beam irradiation and subsequent thermal annealing. The emission, together with noncytotoxicity and easiness of surface functionalization, makes nano-sized diamonds a promising fluorescent probe for single-particle tracking in heterogeneous environments. We present the result of our characterization and application of single fluorescent nanodiamonds as cellular biomarkers. We found that, under the same excitation conditions, the fluorescence of a single 35-nm diamond is significantly brighter than that of a single dye molecule such as Alexa Fluor 546. The latter photobleached in the range of 10 s at a laser power density of 10(4) W/cm(2), whereas the nanodiamond particle showed no sign of photobleaching even after 5 min of continuous excitation. Furthermore, no fluorescence blinking was detected within a time resolution of 1 ms. The photophysical properties of the particles do not deteriorate even after surface functionalization with carboxyl groups, which form covalent bonding with polyL-lysines that interact with DNA molecules through electrostatic forces. The feasibility of using surface-functionalized fluorescent nanodiamonds as single-particle biomarkers is demonstrated with both fixed and live HeLa cells.
Fu
Chi-Cheng
CC
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
Lee
Hsu-Yang
HY
Chen
Kowa
K
Lim
Tsong-Shin
TS
Wu
Hsiao-Yun
HY
Lin
Po-Keng
PK
Wei
Pei-Kuen
PK
Tsao
Pei-Hsi
PH
Chang
Huan-Cheng
HC
Fann
Wunshain
W
D015415:Biomarkers / Q000032:analysis / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D018130:Diamond / Q000032:analysis* / Q000737:chemistry*; D005453:Fluorescence; D006367:HeLa Cells; D006801:Humans; D015336:Molecular Probe Techniques; D015335:Molecular Probes / Q000032:analysis* / Q000737:chemistry*; D049329:Nanostructures / Q000032:analysis* / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry; D055672:Static Electricity
D015415:Biomarkers; D015335:Molecular Probes; D011107:Polylysine; D018130:Diamond; D004247:DNA