Biomedical Engineering Reference
In-Depth Information
For instance, Turner
et al.
reported a novel technique for the
in situ
analysis and monitoring
of live embryonic stem cells that is based on Raman microscopy [32]. In particular, a
coherent anti-Stoke Raman spectroscopic method (CARS) was utilized to obtain biomolec-
ular spectroscopy due to the fact that the signals generated by coherent excitation and signal
emission are remarkably stronger than that of standard, spontaneous Raman spectroscopy
(Figure 19.5A). To this end, the authors focused on genetic materials such as DNA, RNA,
and its complexation with ribosomal proteins, which correlated with Raman peaks at
788 cm
−1
(OP-O stretch, DNA) and 811 cm
−1
(O-P-O stretch, RNA) (Figure 19.5B and C).
By analyzing the CARS mapping images that were obtained and the mean CARS intensities
(A)
Lamp
OPA
Ti: Sapphire
laser
ω
2
Variable
Objective
ω
1
800 nm
Variable
slit
Cells growing
on mirrored
substrate
Tissue culture plate
Delay
line
CCD Camera
PMT
Diffraction
gratings
2ω
1
-ω
2
Filter
(B)
(C)
30
30
1
1
20
20
0.5
0.5
10
10
0
0
0
0
0
10
20
0
10
20
x (μm)
x (μm)
Figure 19.5
Coherent anti-Stoke Raman spectroscopy (CARS) analysis of living ESCs [32]. (A)
Instrumentation set-up and optical path. For all image data, the pump and Stokes beam pulse energies
were both ~1 nJ pulse
−1
at the sample. The CARS images of undifferentiated mouse ESCs are shown
at (B) 788 (O-P-O stretch, DNA) and (C) 811 cm
−1
(O-P-O stretch, RNA) in picosecond mode (20 cm
−1
resolution). Reproduced from Konorov
et al
., 2007 with permission from ACS.
