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Zero-Mode Waveguides for Single-Molecule g g Analysis at High ...

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<strong>Zero</strong>-<strong>Mode</strong> <strong>Waveguides</strong> g <strong>for</strong> <strong>Single</strong>-<strong>Molecule</strong><br />

g<br />

<strong>Analysis</strong> <strong>at</strong> <strong>High</strong> Concentr<strong>at</strong>ions<br />

Cha Seoncheol<br />

Sogang University, Department of Physics, Soft M<strong>at</strong>ter Optical Spectroscopy


Review<br />

Fluorescence Correl<strong>at</strong>ion Spectroscopy<br />

APD<br />

Transsmittance<br />

10 1.0<br />

0.8<br />

0.6<br />

0.4<br />

0.2<br />

0.0<br />

DM570<br />

BA575<br />

TMR<br />

400 500 600 700<br />

Wavelength(nm)<br />

Laser Source<br />

Autocorrel<strong>at</strong>ion function<br />

< δ Ft () δFt ( + τ)<br />

><br />

G(<br />

τ ) =<br />

2<br />

< Ft () >


Review<br />

Fluorescence Correl<strong>at</strong>ion Spectroscopy<br />

APD<br />

APD<br />

Transmittancee<br />

1.0<br />

0.8<br />

0.6<br />

0.4<br />

02 0.2<br />

0.0<br />

DM570<br />

BA575<br />

TMR<br />

400 500 600 700<br />

Wavelength(nm)<br />

Laser Source<br />

Cross Correl<strong>at</strong>ion function<br />

< δδ F F1 () t δδ F F2 ( t + ττ<br />

) ><br />

G(<br />

τ ) =<br />

< F() t >< F () t ><br />

1 2


Review<br />

Fluorescence Correl<strong>at</strong>ion Spectroscopy<br />

P.Schwille., Biophysics Textbook Online (2001).


Review<br />

<strong>Single</strong> <strong>Molecule</strong> Spectroscopy<br />

Considering 1n mol/L solution<br />

0.2μm V eff = π 3/2 r 0 2 z0 ~ 10fL<br />

3μm<br />

1n mol/L · V eff · N a ~ 6<br />

roughly six per volume element<br />

In 100pm ~ 1nm range,<br />

This method is able<br />

to show single molecule dynamics


Why<br />

Limit<strong>at</strong>ion of FCS


Why<br />

Previous approaches to overcome limit<strong>at</strong>ion of FCS<br />

T. E. Starr, N. L. Thompson, Biophys. J. 80, 1575 (2001).<br />

F. de Lange et al., J. Cell Sci. 114, 4153 (2001).


Review<br />

<strong>Single</strong> <strong>Molecule</strong> Spectroscopy<br />

V eff ~ 1fL<br />

0.2μm<br />

3μm μ<br />

V eff ~ <strong>at</strong>to~zeto liter<br />

KTS K.T.Samiee, i et t al., l Bi Biophys. ph J J. 88 88, 2145 (2005).<br />

(2005)


How<br />

Setup<br />

60x w<strong>at</strong>er immersion<br />

(NA ( = 1.2) )<br />

488nm circularly<br />

polarized light


How<br />

<strong>Zero</strong> <strong>Zero</strong>-<strong>Mode</strong> <strong>Mode</strong> Waveguide (Example)<br />

a<br />

y z<br />

a<br />

x<br />

Perfect conductor<br />

��<br />

⎧⎪E⎫⎪ ⎨ ⎨�� ⎬<br />

⎪⎩B⎪⎭ 2 2<br />

( ∇ + μεω μεω ) = 0<br />

��<br />

⎧ ⎫<br />

2 2 2 ⎪E ⎫⎪<br />

[ ∇ t + ( μεω − k )] ⎨�� ⎬=<br />

0<br />

⎪⎩B⎪⎭ �� ��<br />

Exyzt ( , , , ) = Exye ( , )<br />

�� ��<br />

Bxyzt ( , , , ) = Bxye ( , )<br />

2 2 2<br />

μεω −k≡ γ > 0 By B.Cs<br />

So So, this equ<strong>at</strong>ion has the modes .<br />

± i( kz−ωt) ± i( kz−ωt) Jackson (1999)


How<br />

<strong>Zero</strong> <strong>Zero</strong>-<strong>Mode</strong> <strong>Mode</strong> Waveguide (Example)<br />

y z<br />

a<br />

x<br />

2<br />

[ ∇ t + γγm ] ψψm<br />

= 0<br />

2 2 2<br />

∇ + k m = μεω μ m −γγ<br />

m<br />

Define<br />

From B.Cs<br />

1 1<br />

k = 2π<br />

−<br />

λ λ<br />

a 2 2<br />

m<br />

Perfect conductor<br />

ω<br />

m<br />

2<br />

m<br />

=<br />

γ =<br />

λλ<br />

m<br />

~<br />

γ m<br />

με<br />

2π<br />

m<br />

2<br />

a<br />

a<br />

2 2<br />

For longer wavelength (λm>a) are evanescent<br />

and their intensity decays exponentially<br />

along the length z of the guide<br />

I( z) ∝ e<br />

ikz<br />

Jackson (1999)


How<br />

<strong>Zero</strong> <strong>Zero</strong>-<strong>Mode</strong> <strong>Mode</strong> Waveguide (Example)<br />

y z<br />

a<br />

x<br />

Perfect conductor<br />

For circular waveguide case,<br />

1 1<br />

k = 2 − 2<br />

λ 1.7d<br />

I( z) ∝ e<br />

ikz<br />

Jackson (1999)


How<br />

<strong>Zero</strong> <strong>Zero</strong>-<strong>Mode</strong> <strong>Mode</strong> Waveguide<br />

For<br />

Real Metal (Skin depth Effect)<br />

-> Solving by Numerical Method


Calcul<strong>at</strong>ion<br />

Coupling Efficiency<br />

radi<strong>at</strong>ive r<strong>at</strong>e of a dipole<br />

∝ density of photonic st<strong>at</strong>es available <strong>for</strong> emission<br />

Approxim<strong>at</strong>ion : k r(z) ~ p(z)<br />

k kr ( z ) p ( z )<br />

Qz ( ) = ≈<br />

k ( z) + k p( z) + C<br />

r nr<br />

constant such th<strong>at</strong><br />

Q(0) equals the quantum yield<br />

p(z) : Averaging over all dipole orient<strong>at</strong>ions yields


Calcul<strong>at</strong>ion<br />

Effective Volume<br />

p( z)<br />

Sz ( ) = Izpz ( ) ( )<br />

p( z) + C<br />

V<br />

eff<br />

∫<br />

∫<br />

4<br />

2<br />

3 2<br />

π d ( Szdz ( ) ) 1.56πLλ<br />

= =<br />

2<br />

2 2<br />

4 S ( z) dz λ − 36L<br />

3 2<br />

1.56πLλ<br />

Veff | L= 14m ~ | 2 2 L= 14m<br />

~14zl<br />

λ −<br />

36L


Calcul<strong>at</strong>ion<br />

Correl<strong>at</strong>ion Function<br />

1-Dimensional Diffusion<br />

∞<br />

2<br />

2 −υ<br />

Dτ<br />

G( ) ∝ ∫ ( S( z)cos( z) dz) e d<br />

υ ∫<br />

τ υ υ<br />

L<br />

b by perfect f t conductor d t approxim<strong>at</strong>ion i ti<br />

τ d<br />

π τd τd 2 τd 1/2 d erf ( R)<br />

τ<br />

− τ<br />

G( τ ) = G0[ ((1−2 ) e erfc(<br />

− ( ) )) −<br />

] 2 2<br />

4 ττ ττ ππ<br />

ττ ττ<br />

(1 + R )<br />

K.T.Samiee, et al., Biophys. J. 88, 2145 (2005).


Results<br />

Correl<strong>at</strong>ion Function<br />

N<br />

R110dCTP : Rhodamine green + dCTP G(0)<br />

=<br />

2<br />

( N + B )<br />

Free parameter is only waveguide diameter in fits<br />

<strong>Zero</strong>-<strong>Mode</strong> Waveguide increases<br />

temporal resolution significantly


Results<br />

Correl<strong>at</strong>ion Function


Results<br />

Correl<strong>at</strong>ion Function

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