Biomedical Engineering Reference
In-Depth Information
ensemble bundles, suggesting that dispersed CNTs are eficient NIR emitters.
The high stability is another advantage of CNT-based luorophors.
50
CNT
luorescence was extremely photostable, showing no evidence of blinking or
photobleaching after prolonged exposure to excitation at high luorescence.
Figure 7.8 shows the rates of photobleaching of the NIR organic luorophore
78-CA, NIR quantum dots consisting of a CdTe core and CdSe shell, and CNTs.
The dispersed SWNTs did not show attenuation of luorescence emission
after exposure to excitation at a luence of 6.17 × 10
6
mW/cm
2
for 10 hours.
Because of these novel properties and advantages, the NIR luorescence has
attracted more and more attention in the area of biosensing and analysis.
Figure 7.8
Fluorescence intensity-exposure time curves. CNTs showed higher
photostability than organic luorophore 78-CA and quantum dots. Reproduced from
Cherukuri
et al.
54
with permission.
Heller
et al.
53
reported a study of incubated live murine 3T3 and myoblast
stem cells with ssDNA-wrapped SWNTs. The excitation radiation passes
through live cells without signiicant scattering, absorption, heating, or
damage to tissues. The CNT luorescence did not photobleach even under
prolonged excitation and remained visible after a week in live cells. Cherukuri
et al.
54
found that macrophage cells could ingest substantial amount of
SWNTs. Those SWNTs emitted luorescence around the wavelength of 1100
nm, making it possible to trace the interaction of CNTs with cells and give
high-contrast imaging of the cells.
An advantage of CNT-based luorescence emitters is that they can be easily
modiied with functional ligands for cell targeting and can act as cancer cells
tracers. Folate moiety, which is a cancer-cell-targeting ligand, was linked with
CNTs to selectively target cancer cells.
49
Conjugation of SWNTs with antibodies
also made the system targeting luorescence to speciic cells. Rituxan, an
antibody that recognizes the CD20 cell surface receptor, was coupled to an
Search WWH ::
Custom Search