applications des lasers impulsionnels en biologie...
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Applications des lasers impulsionnels en biologie :
résolution spatiale etgénération de contraste
Pierre-François LENNEInstitut Fresnel - Marseille
The cell
5 nm
5 nm
2 nm
10 µm
Mitochodrion
Energy Production
RoughEndoplasmicReticulum
Protein production
DNA contains the informationfor the production of proteins
PlanI- Introduction - Rappels
• Résolution spatiale
• Microscopie de fluorescence excitée par l’absorption de 1 et 2 photons
II- Réduction du volume de détection et résolution sub-longueur d’onde : la microscopie STED
III- Le contraste vibrationnel : la microscopie Raman stimulée CARS
The Airy pattern radius fromthe central peak to the firstminimum is given by : NA
Rairy 222.1 λ
=
θsinnNA =
Object plane Image plane
θ
Tube lens
)(22.1
objectivecondensorairy NANA
R+
=λ
Conventional contrast in optical microscopy
Airy pattern
Condensor
RésolutionCritère de résolution :
NANArxyλλ 61.0222.1 ==
Fluorescence Microscopy
1P Fluorescence Microscopy
1P Confocal Microscopypinhole
2P Fluorescence Microscopy
1-photon 2-photon
I2P~(Iexc)2
molec s/molec = 10 GM
Ordre de grandeurs :Microscopie à 2 photons avec laser continu vs impulsionnel
•Laser continu focalisé dans un échantillon de fluorescéine de 10 µM produit 20000 photons/s. Efficacité de détection 5 % 103 photons/s détectés.
•Laser impulsionnel
)/()()( 22 τRtIgtIF p=∝
mWtI 1)( =
Facteur de formeDurée de l’impulsion
Taux de répétition
510)/( =τRgp
108 photons/s détectés.
fs 100 MHz, 80 R gaussien), (profil 66.0 === τpg
Resolution in Fluorescence Microscopy
Wide Field Confocal 1P 2P λ=0.5µmNA=1.2n=1.33
0.25µm / 0.16µm / 0.263µm
0.92µm / 0.65µm /1.07µm2)(
2NA
nrzλ= ( )24.1
NAnrz
λ=
NArxyλ4.0=NArxy
λ61.0=NArxyλ7.0=
( )23.2NA
nrzλ=
Wide Field 1P Confocal
Avantages de la M2P•Excitation localisée
photoblanchîment et photodestruction réduits
• Faible absorptionImagerie en profondeur (tissus)
II- Réduction du volume de détection et résolution sub-longueur d’onde : la microscopie STED
Excitation Stimulated emission depletion
STED
+ =
~ 100 nm
~ 100 nm
Confocal microscopy + STED
T.A. Klar, PNAS USA 97, 2000
Non linear Optics: Stimulated emission depletion
STimulated Emission Depletion - STED
Utilisation d’une non linéarité entre intensité d’excitation et émission de fluorescence
λ
STimulated Emission Depletion - STED
Ti:Saph76 MHz
OPO + SHGEX0.2 ps560 nm
STED40 ps765 nmstrecher
EX STED
Fluo
λ
STimulated Emission Depletion - STED
fluorescence relaxation
STED(40ps)
excitation pulse (0.2ps)
Cyclic process at a frequency of 40 MHz
STimulated Emission Depletion - STED
E
vibSTEDSTED
FSTEDSTED
kNININdt
dN
kNININdt
dN
*0
*01
*0
11*
011
/
/
−−=
−+−=
σωσ
σωσ
h
hN1
ISTED
If σISTED<<kvib then N0*=0 and re-excitation is negligible
N0*
kvib)/(1 ωτσ hSTEDIExpN −∝
Strong non-linear dependence of N1 with ISTED Non linear Depletion
STimulated Emission Depletion - STED
97 nm FWHM , Z depth and XY !!! = 670 zeptoliters = 0.67 attoliter
STimulated Emission Depletion - STED
STEDConfoc
S. cerevisiae yeast cell
STEDConfoc
Latex beads 100 nm
Exogenous fluorophoreNeed to be introduced in the living sample.QuenchingArises from a variety of competing processes that induce non-radiative relaxation of excited state electrons to the ground state.Photobleaching Occurs when a fluorophore permanently loses the ability to fluoresce due to pchemical damage and covalent modification.
Quenching and Photobleaching
Typical example of photobleaching (fading) observed in a series of digital images captured at different time points for a multiply-stained culture of bovine pulmonary artery epithelial cells. - Nuclei stained with 4,6-diamidino-2-phenylindole (DAPI; blue fluorescence)- Mitochondria stained with MitoTracker Red (red fluorescence)- Actin cytoskeleton stained with phalloidin derivative (green fluorescence)
III- Contraste vibrationnelCoherent Anti-Stokes Raman Microscopy
CARS
A. Zumbusch, G. R. Holtom, and X. S. Xie, Three-Dimensional Imaging by Coherent Anti-Stokes Raman Scattering, Phys. Rev. Lett. 82, 4142, 1999
Spontaneous Raman Scattering
Anti-Stokes
Stokes
ωωP ωASωS
ΩR ΩR
PS=σR IPσR=10-31 – 10-29cm2/molecule
NB: σF-1P=10-16cm2/moleculeσF-2P=10-49cm4.s/molecule
Stimulated Raman Scattering
ωpωpωs
ωas
Ωr
If ωp-ωs=Ωr resonant effect:ωas is enhanced
FCARS
E-CARS
CARS versus Spontaneous Raman
wavelength
Laser ωp
Spontaneous RAMAN
Stokes ωs
AntiStokes ωas
Stokes ωs
AntiStokes ωas
ΩR ΩR
From the theory…
From the theory…2
)()( ASNL
AS PI ωω ∝
*2)3( )()()( SSPPASNL EEP ωωχω =
SPAS ωωω −= 2
ICARS∝ N2F
ks
-ks
kp kp
kAS
)2( spAS kkkk −−=∆
F-CARS and E-CARS…
From Cheng et al, J. Opt. Soc. Am. B 19 1363 (2002)
FCARS
E-CARS
F-CARS and E-CARS
Melanine beadsin agarose gelS: 10450 cm-1(957nm)P: 11177 cm-1(894nm)P:20mWS:10mW Agarose/glass interface
0.75µm
0.28µmPolystyrene beadsin agarose gelS: 11009 cm-1(908nm)P: 14054 cm-1(711nm)
From Cheng and Xie J. Phys. Chem. B, 108, 827 (2004)
Spectral shape…Electronic state
tpt
tNR
RspR
R
iA
iA
Γ−−++
Γ+−−Ω=
ωωχ
ωωχ
2)()3()3(
ΩR ΩR
ωS
ωS
ωPωP
ωP
ωP
ωS
ωAS ωASωAS ωPωP
R)3(χ Far from two photons absorption
Spectral width
CARS line profile as a function of the pulse widthΓR=10cm-1
Resonant and non resonant CARSAs function of pulse width
From Cheng and Xie J. Phys. Chem. B, 108, 827 (2004)
From the experiment…
CARS Set Up
Nd:Vd VERDI 10W
MIRASaphirTitane
(Maître)
MIRASaphirTitane
Esclave
PulseSelect
PulseSelect
SynchroLock
APD
Platine PZT XYZ
Echantillon
Objective Microscope NA1.2
FiltreM
BS
M
M
M
Delai
(λ/2)+Glan
ωP+ωSωAS
PZT
Filtres
Monochromateur
Télescope
APD
Filtres
Objective Microscope NA 0.5
E-CARS
F-CARS
M BS
APDAPD
ωPωS
ωAS
Rétroréflecteur
BS : séparatrice 50/50M : MiroirPZT : PiézoélectriqueAPD : Photodiode à avalanche
CARS Set Up
Imaging polystyrene beadsC=C 1600cm-1 (ωp750nm-ωs850nm) ωAS
x
z
ωP
ωAS
ωS
15
10
5
0
Y (µ
m)
151050X (µm )
1.0
0.8
0.6
0.4
0.2
0.0
CA
RS
In
ten
sity (
no
rm)
151050X (µm)
∆X = (7.458 ± 0.129) µm
1.0
0.8
0.6
0.4
0.2
0.0
CA
RS
Inte
nsity (
norm
)
20151050Z (µm)
∆Z = (6.2028 ± 0.0911) µm
∆X=7µm ∆Z=6.3µmF-CARS - 6µm beads
E-CARS – 0.1µm beads ∆X=0.57µm ∆Z=1.5µm
1.0
0.8
0.6
0.4
0.2
0.0
CAR
S In
tens
ity (n
orm
)
2 0151 050Z (µm )
FWHM = 1.52 µm
1.0
0.8
0.6
0.4
0.2
CAR
S In
tens
ity (n
orm
)
2.01.51.00.50.0X (µm)
FWHM=574 nm
1.5
1.0
0.5
0.0
Y (µ
m)
1.51.00.50.0 X (µm)
400 kHzP: 160µWS: 80µW
Temporal detuning
Delay between ωp and ωs pulses(in ps)
CARS signal at 660nm
Lipid membranes…
Polar
2µm
E-CARS spectrum of a multilamellar layer of DOPC on a clean glass coverslip. Thepump beam was fixed at 13990 cm-1
(714nm).CARS signal from the lipids peaks at 2849 cm-1, (symmetric CH2 vibrational mode).
F-CARS image of erythrocyte ghost. Image was taken in the equatorial xy plane of the vesicle at a Raman shiftof 2845 cm-1.
From Potma et al, J. Raman. Spec. 34, 624 (2003)
Lipid membrane and H20
E
E E
E5µm
F-CARS images of POPS multilamellar onions prepared at 27°C. ωp-ωs was tuned to 2845 cm-1 (C-H strech) and 3445 cm-1 (O-H strech). The number of bilayers was estimated to be 500.The pump frequency was fixed at 14212 cm-1 (704nm). P: 100 mW and S: 50 mW - repetition rate 80 MHz
POPS (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine) Adapted from Cheng et al PNAS 100, 9826 (2003)
Cheng et al, Biophys. J. 83:502Living cells…C-H strech
NIH 3T3 cells in interphase. Aliphatic C-H stretching 2970 cm-1
Pump 14054 cm-1(711nm) and the Stokes 11184 cm-1(894nm). P: 40mW; S: 20mW
Interphase NIH3T3 cell mitochondriaF-CARS: C-H Strech
Fluo: mitotracker Red.
Adapted from Cheng et al Biophys. J. 83, 502 (2002)
3D sectioning C-H strech
Three dimensional distribution of lipids in epithelial cells.CH2 stretching vibration (2845 cm-1).Lipid granules and plasma membranes.
http://bernstein.harvard.edu/research/cars.html
Living cells…PO2- strech
F-CARS images of a NIH 3T3 cell in metaphase at different depths. PO2
-symmetric stretching vibrational frequency at 1090 cm-1.Pump 13593 cm-1(735nm) and Stokes 12503 cm-1(800nm). P: 40mW, S: 20mW, 400kHz
Intracellular hydrodynamics O-H strech 3300 cm-1
living D. discoideum cellsOH strech 3300 cm-1
OD strech 2800 cm-1
D2O H2OH2O
From Potma PNAS 98, 1577 (2001)
D2O
t=0H2O
ωP ωS3300 cm-1 OH strech
Permeability of the plasma membrane Pd=2.2 µm/sDw=5 µm2/s (10%-20% of the cell diameter)Dw>500 µm2/s (central cell region) Dw
Exceptionally low Dw due to the presence of densely packed actinfilaments in this region that provide an additional barrier in theprocess of water diffusion.
- CARS addresses molecular intrinsic vibrational transition and does not requires staining with fluorophore or radioactivity.
-CARS is a coherent process which builds an anti-stokes wave on a large number of molecular bonds. This coherent process permits to obtain a signal orders of magnitude larger than spontaneous Raman scattering. Small laser powers (1mw) can be used which are compatible with bio-objects.
- CARS is selective of a certain molecular bond (by adjusting the detuning between laser and Stokes beam)
- CARS is a non linear process which takes place only at the focal point of the microscope lens (diffraction limited) . Therefore the confocal effect is automatic and permits 3D imaging of bio-objects.
- Working in IR limits the absorption and diffusion of bio- tissue. Image as far as 0.3mm in depth can be obtained in living tissues.
- CARS is an elastic process which does not store energy into the system. It is therefore insensible to bleaching as fluorescence is.
- Finally, CARS is not affected by endogenous fluorescence because the Anti-Stokes signal is at lower wavelength than the pump lasers.
Institut Fresnel
STICCentre d’Immunologie de Marseille Luminy (CIML)
SDV
D. MarguetA.SergéM. FalletA. BonedL. WawrezinieckO. Wurtz
H. RigneaultF. BeloniN. DjakerP.-F. Lenne S. Monneret