2017-07-04

1

Neutron Scattering for Soft Matter- Lipid Membranes Interacting with Proteins

- Binary Superlattices of 1D Colloids

Sung-Min Choi

Neutron Scattering and Nanoscale Materials Lab.Dept. Nuclear and Quantum Engineering

KAIST(sungmin@kaist.ac.kr)

• Basic Concepts of Neutron Scattering• Lipid Membranes Interacting with Proteins• Binary 1D Colloidal Superlattices

Neutrons for Soft Matter

Spherical Micelle

Rod-likemicelle

LamellarVesicles

2-4 nmin Water

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Infrared UVCold Neutron

soft x-ray x-rayNeutron

Microwave

Electron Microscopy (destructive)STM (surface)

In-situ analysis : Neutron & X-rayWe need

Measurement Techniques

1 nanometer1cm 1mm 1m

10-2m 10-3m 10-4m 10-5m 10-6m 10-7m 10-8m 10-9m 10-10m

Natural

Protein

Manmade

Nanotube electronics

What Neutrons See

C. G. Shull B. N. Brockhouse

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Length scale (Å)

Tim

e sc

ale

(sec

)

Dynamics : femto sec- 100 nano sec

Neutrons probe Structures & Dynamics

DynamicsDynamics

SPIN ECHOSPIN ECHO

Back scatteringBack scattering

TOF/TASTOF/TAS

FANSFANS

SurfaceSurface TEM/SEMOptical

Internal StructureInternal Structure

Neutron DIFF

SANS/REF

Structure : 0.1 nm – 100’s nm

Neutron Sources

Use Thermal Energy

~1000’s MWth

Nuclear Power Plant

Neutrons

Research Reactor

Use

10’s MWth

Nuclear Fission

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Proton accelerator based neutron source

Spallation Neutron Source

Particle and Wave Properties of Neutron

y) x velocitmass(neutron

constant) s(Planck'

vm

h

Fast Neutron

V ~ 20,000,000 m/sec~ 0.00002 nm

tThermal Neu ron

V ~ 2,000 m/sec

~ 0.2 nmModeratorWater~35°C

Cold Neutron

V ~ 200 m/sec

~ 2 nmModeratorLiquid H2

~25 K

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Wavelength ~ Å, nm(thermal & cold neutron)

Energy ~ meV

Spin =1/2

Interacts with nuclei

No charge

Atomic & Nano length scale

Same magnitude as basic excitations in matter

Magnetic structure &dynamics

Why Neutrons ?

Contrast variation

Deep penetration

NIST, US

ORNL, US

SNS, US

ANSTO, Australia HANARO, Korea J-PARC, Japan

JRR-3, Japan

ILL, France

ISIS, UK

FRM-II, Germany

ESS, Sweden

Major Neutron Facilities in the World

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Four Circle Diffractometer

High Resolution Powder Diff.

NeutronRadiography

High IntensityPowder Diff.

Cold Neutron Guide

Bio-Diffractometer

Triple Axis Spectrometer

PGAA

Test Station & Residual Stress

Instrument

HANARO Thermal Neutron Facility

• 1995: 1st critical• Power: 30MW• Flux: ~2x1014 n/cm2sec

HANARO Cold Neutron Facility

40m SANS

18m SANS

Vertical-REF

DC-TOF

Horizontal-REF

Cold TAS

USANS

Thermal Neutron Instruments Cold Neutron Facility

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Basic Concepts of

Neutron Scattering

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Young’s Double Slit Experiment

Interference PatternIncoming plane wave Scattered wave

δ

4. Size of the slits, δ

1. Wavelength of the incident wave, λ2. Distance between the slits, d3. Distance from the slits to the detector, L

λ

d

L

InterferencePattern

Young’s Double Slit Exp. with Different Distance between Slits

• The distance between slits determines the interference pattern (periodicity).

Therefore, • If we measure the interference pattern,

we can determine the distance between slits.

d

'd’

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Young’s Double Slit Exp. with Different Slit Size

if slits are VERY small

• The envelope of interference pattern is determined by the size of slits.

Therefore, • If you measure the envelope the interference pattern, we can determine the size of slits.

Fourier Transform

Fourier Transform in Nature : Rainbow

Prism

Fourier Transform is decomposition or separation of a function into a sum of sinusoidsof different frequencies.

t

h(t)

T

Frequency :T

f1

Period

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Fourier Transform in 1D

time

T

x

Time domain Real space

: wavelength (cm)T : period (sec)

Tf

1 : time frequency (sec-1)

Tf

22 : angular frequency

(radians sec-1)

2

Q : spatial frequency (radians cm-1)

: wave vector

dtethH ti )()(

dxexhQH iQx)()(

)(xh)(th

dQeQHxh iQx)()(

deHth ti)()(

Fourier Transform : Examples

xQAxh ocos)(

x

2

oQ

Q

H(Q)

real-Qo +Qo

F.T.

dxexQAQH iQxo )cos()(

)()(222

)()(oo

xQQixQQiiQxxiQxiQ

QQQQA

dxedxeA

dxeee

A oo

oo

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Fourier Transform : Examples

Q

h(x)

-xo +xo

F.T.

H(Q)

x

Fourier Transform: Examples

x Q4

a

4

a

a

4a

8a

4

a

8

h(x) H(Q)

F.T.Ao

x Q2

a

2

a

a

2a

4

a

6a

2

a

4

a

6

h(x) H(Q)

F.T.

Top Hat function Sinc function (sinx/x)

Ao

2/

)2/sin()(

Qa

QaaAQH o

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Fourier Transform: Convolution Theorem

Convolution

Multiplication

F.T.

H(Q) = G(Q) × F(Q)

dxfgxh )()()(

)()( xfxg

)()()( xfxgxh

Fourier Transform: Convolution Theorem

=

g(x) f(x)h(x)

x

F.T.

F(Q)

Q

F.T.

=

H(Q)

Q

F.T.

×

G(Q)

Q

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Re-Visit Young’s Double Slit Exp.

if slits are VERY small

Q

h(x)

-xo +xo

F.T.

H(Q)

x

The interference pattern is|Fourier Transform of two slits|2

Re-Visit Young’s Double Slit Exp.

h(x)

-xo +xo

F.T.

x

The interference pattern is|Fourier Transform of two slits|2

Q

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The interference pattern ofYoung’s double slit experiment

is|Fourier Transform of two slits|2

Young’s Double Slit Experiment

Interference PatternIncoming plane wave Scattered wave

δ

λ

d

L

1

2

21 2

21

2 I

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Young’s Experiments with Neutron Wave and Atoms

Neutron Scattering

AtomsIncident Neutron WaveDetector

(counts neutrons)

2

j

RQ-ij

jebdΩ

dσ

Add up phase factors of the scattered waves from all the scattering centers in the sample.

Differential Scattering Cross Section

Φd

d

d

d into secondper scattered photons of No.

ddr

drdA

sin 2

2

inin Ek ,

outout Ek ,

x

y

z

incident photons

scatteredphotons

transmittedphotons

Sample

Detector

secondper per neutronsincident of No. 2cmΦ

ddr

dAd sin

2detector

detector

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jout Rn

jR

0

ink

outk

ie

iRkki ee jinout

)(

Scattering Vector Q and Scattering Cross Section

2

j

RQ-ij

jebdΩ

dσ

Add up phase factors of the scattered waves from all the scattering centersin the sample.

jb = scattering length of the j-th nucleus

jin Rn

ininin kkn

/

outoutout kkn

/jin Rk

jout Rk

inout kkQ

LengthQ

1 ofUnit

jRQie

inout kkQ

2

koutin kk

ink

outk

Q

For elastic scattering

2sin2

kQ

2sin

4

Q

Scattering vector Q

Note: The dimension of Q = 1/Length

dQ

2

Qd

2or

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What Contrast do we use in Neutron Scattering ?

)()( rBμr MV

)(2

)(2

rr N

nN b

mV

Neutron Interaction Potentials

: Neutron-Nucleus

: Neutron-Magnetic Field

Scattering Length

b = bN ± bM

Nuclear Magnetic

V

bn

jj

Scattering length density,

= bound coherent scattering length of atom jjb

V = volume containing the n atoms

Neutron Scattering Length Density

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SL

D (

1010

cm-2

)

0

H2O-0.56

D2O6.65

SLD bi

i

n

V

NA

mass

Mw

i

bi molecule

N A Avogadro' s number = 6 1023

Mw molecular weight

bi bound coherent scattering length of atom i

H2O + D2O(1:1 volume)

3.05

• H2O + D2O mixture (1:1 volume)SLD ,Mixture xH2O SLD ,H2O (1 xH2O ) SLD ,D2O

0.5 (0.56 1010 cm 2 ) 0.5 (6.65 1010 cm 2 )

3.05 1010 cm 2

- bound coherent scattering length (10-13 cm) bH = -3.74 bD = 6.67 bO = 5.80

• H2O

• D2O

SLD ,H2O (6 10 23 / mol )1.0g / cm 3

18g / mol

2 bH bO

0.56 10 10 cm 2

SLD , D2O (6 1023 / mol )1.1g / cm 3

20 g / mol

2 bD bO

6.65 1010 cm 2

Calculation of Neutron Scattering Length Density

Neutron Contrast Variation

Neutron interacts with Nuclei.

HD

CO

Si

Isotope substitution (H/D)

Neutron cross section.

• VERY sensitive to Hydrogen• H and D are VERY different

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H2O/D2O mixtures can contrast match most materials

SL

D (

x10-1

0cm

-2)

Mole fraction D2O

H2O

D2O

2

)( j

RQij

jebQd

d

Neutron Scattering : Fourier Transform

Differential scattering cross-section

2

)()(

rderQd

d rQisld

)()( jj

Rrrn

: Atomic number density

j

jj Rrbr )()( sld

: Scattering length density

1)r( rd

)R()R-r()(

frdrf

Dirac delta function

jRQi

jj

rQij

jj

rQi ebrdeRrbrderr )()()(F.T. sldsld

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Young’s Experiments with Neutron Wave and Atoms

Neutron Scattering

AtomsIncident Neutron WaveDetector

(counts neutrons)

Fourier Transformof atomic positions

2

)()(

rderQd

d rQisld

Small-Angle Neutron Scattering

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range 0.001 Å-1 to 0.8 Å-1

Small-Angle Neutron Scattering

ink

outkQ

inout kkQ

2sin

4

2sin2

kQ

sampleincident neutrons

Q

Length scale, 1 nm to 500 nm 5 to3.0

d

Qd 2

Small scattering angle,

We measure the interference pattern from structures.

)(Q

d

d= differential scattering cross-section

• SANS measures the bulk nanostructures of 1 nm – 100’s nmin solids, liquids, gel or mixtures.

• Practically, anything that has proper1) length scale, 2) neutron contrast and 3) sample volume

0.1 ~ 10 mm

1.0 ~ 2.5 cm (beam diameter)

Typical sample volumeNeutron scattering length density

Systems that SANS Can Measure

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HANARO Cold Neutron Research Facility

40m SANS

18m SANS

Bio-REF

USANS

Cold TAS

Vertical-REF

DC-TOF

SANS Measures the Inhomogeneity of the Scattering Length Density in Sample

2)( of TransfomFourier )( rQ

d

d

2

)(1

)(1

)(

rrQQ rQ deVd

d

Vd

d i

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What Information from SANS ? Particulate Systems

2( ) Fourier Transfom of ( )

d

d

Q r

)( )(

1)( )(2

QQ

Q RRQ

SPn

eN

FV

N

p

N

i

N

j

i

P

pp p

ji

Structure factorInter-Particle interference

Interactionbetween particles

Form factorIntra-Particle interference

Shape and dimensionsof particles

Remember the convolution theorem

Positions of particlesShape and Size

of particles

Convolution

pN

jjRrrn )()( )( rf

)(r

Particles dispersed in solvent

FT FT

p

j

N

j

RQ-ie

rderfQF rQi

)()(×

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2

3

3(sin( ) sin( ))( )

( )

QR QR QRP Q

QR

221

0

2 ( sin ) sin(( cos ) / 2)( ) sin

sin cos ) / 2

J QR QLP Q d

QR QL

2

1 13 ( ) ( ) 3 ( ) ( )( ) c c s c s s solv s

c s

V J QR V J QRP Q

QR QR

Sphere

Cylinder

Core-Shell

Particle Form Factors

Thiolated PEG

Attaching Molecules on the Surface of Gold Nanoparticles

What is the shell thickness of the functionalized gold nanoparticles in water ?

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SANS Measurements and Form Factor Analysis

Spherical Core-Shell Form Factor

0.5 vol % Au-PEG-1 and -2 in D2O Measured using the 40 m SANS at

HANARO

Parameters Au-PEG-1 Au-PEG-2

core radius (Rcore , nm) 6.5 6.5

thickness of shell 1 (Tshell 1 , nm) 2.4 1.6

thickness of shell 2 (Tshell 2 , nm) 1.2 2.0

thickness of shell 3 (Tshell 3 , nm) 0.9 3.4

volume fraction of PEG in shell 1 0.98 0.94

volume fraction of PEG in shell 2 0.51 0.75

volume fraction of PEG in shell 3 0.40 0.37

total shell thickness (nm) 4.5 7.0

Attractive square well

Hard sphere

Coulomb repulsion

Structure Factors

S(Q

)

Q × diameter

S(Q) ≈ 1 when sample is very dilute.

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SANS Intensity

• S(Q) ≈ 1 when sample is very dilute. )()( QPnQI p

)()()( QSQPnQI p

Q

P(Q), scaled

S(Q)

I(Q)

drrQr

QrrQ

d

d

V

22 )sin(

)(4)(

Contrast Correlation function

Orientation average

')'()'(

')'()'()(

rrr

rrrr

d

dr

What Information from SANS ? Non-Particulate Systems

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2

j

RQ-ij

jebdΩ

dσ

2

)()(

rderQd

d rQisld

)()()( QSQPnQd

dp

Summary of Small Angle Neutron Scattering

SANS and SAXS Studies ofBinary Superlattices of 1D Colloids

Hierarchically Self-Assembled Hexagonal, Honeycomb, and Kagome Superlattices

of Binary 1D Colloids

Sung-Hwan Lim, Taehoon Lee, Younghoon Oh, Theyencheri Narayanan, Bong June Sung, and Sung-Min Choi

Highly Ordered and Highly Aligned 2D BinarySuperlattice of a SWNT/Cylindrical-Micellar System

Sung-Hwan Lim, Hyung-Sik Jang, Jae-Min Ha, Tae-Hwan Kim, Pawel Kwasniewski,Theyencheri Narayanan, Kyeong Sik Jin, and Sung-Min Choi

2017-07-04

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Salt

Semiconductor

Diamond

SuperconductorLi-ion battery

Magnets

Atomic Crystals

Nanoparticles as Building Blocks

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Optical

Electrical

Magnetic

Chemical

Emergent Properties

Nanoparticle Supercrystals

Nanoparticle Supercrystals

Closely packed silica nanoparticles (150-300 nm) Diffraction of Light

OPAL

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Binary Superlattice of Spherical Nanoparticles

Kalsin et al. Science 312, 420 (2006) C.B. Murray et al Nature (2009)

C.B. Murray et al Nature (2006)

Slow Solvent Evaporation Induced

Electrostatic Interaction

DNA-Programmed Nanoparticle Superlattice

S-A10-AAGACGAATATTTAACAATTCTGCTTATAAATTGTT-A-GCGC

S-A10- AAGACGAATATTTAACAATTCTGCTTATAAATTGTT-A-ATGC

X

TACG - A -TTGTTAAATATTCGTCTTAACAATTTATAAGCAGAA-A10-S

Y

G C

T A Z

CGCG - A - TTGTTAAATATTCGTCTTAACAATTTATAAGCAGAA-A10-S

Z

FCC

BCC

C.A. Mirkin et al, Nature (2008)

Linker Z Linker Z

Linker X Linker Y

C.A. Mirkin et al, Science (2013)

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Binary Superlattices of 1D Nanoparticles

Spherical Nanoparticles

1DNanoparticles

?

Purdy et al, Phys. Rev. Lett. (2005)

fd-virus (thin) + fd-PEG (thick)

1.1 < Dthick/Dthin< 3.7

Binary Mixture of 1D Nanoparticles

fd-v

irus

(mg

/ml)

fd-PEG (mg/ml)

Gold Nanorods

Slow evaporation on substrate

+

18 nm 45 nm

Aminah and Choi

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Binary Superlattices of 1D Nanoparticles

+

Medhage et al., J. Phys. Chem. 97, 7753 (1993)

Phase separation ? Random mixing ? Something lese ?

?

C12E5/Water

5 nm

4.4 nm

SAXS Measurements at Hexagonal Phase (10 oC)

p-SWNT/C12E5/D2O (15/45/55)

C12E5/D2O (45/55)

Without p-SWNT

With p-SWNT

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40m SANS at HANARO Cold Neutron Facility

40m SANS

SANS: Contrast Matching

Deuteratedp-SWNTs+

Neutron Scattering Cross Section

D2O100%

100

101

102

103

104

105

106

107

I(Q

)

2 3 4 5 6 7 8 90.1

2 3 4

Q (1/A)

100

101

102

103

104

105

106

107

I(Q

)

2 3 4 5 6 7 8 90.1

2 3 4

Q (1/A)

80%

60%

100

101

102

103

104

105

106

107

I(Q

)

2 3 4 5 6 7 8 90.1

2 3 4

Q (1/A)

40%

100

101

102

103

104

105

106

107

I(Q

)

2 3 4 5 6 7 8 90.1

2 3 4

Q (1/A)

20%

100

101

102

103

104

105

106

107

I(Q

)

2 3 4 5 6 7 8 90.1

2 3 4

Q (1/A)

15%

100

101

102

103

104

105

106

107

I(Q

)

2 3 4 5 6 7 8 90.1

2 3 4

Q (1/A)

10%

100

101

102

103

104

105

106

107

I(Q

)

2 3 4 5 6 7 8 90.1

2 3 4

Q (1/A)

100

101

102

103

104

105

106

107

I(Q

)

2 3 4 5 6 7 8 90.1

2 3 4

Q (1/A)

5%

0%10

0

101

102

103

104

105

106

107

I(Q

)

2 3 4 5 6 7 8 90.1

2 3 4

Q (1/A)

D2O100%

45% C12E5 in Water (D2O/H2O)

Contrast Matching

HydrogenatedC12E5

100% D2O

60% D2O

Surfactants C12E5 are not visible by neutron

5% D2O

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2 3 4 5 6 7 8 90.1

2 3

Q(1/A)

SAXS

SANS (without p-SWNT)C12E5 are contrast matched with D2O/H2O

New peak

p-SWNT/C12E5/Water = 15/45/55 at 10 ºC

1

7

1

3

2

SANSDeutrated p-SWNT

1

3

+

Shear-Induced Alignment of p-SWNT/C12E5/D2O

Isotropic

Hexa

Cooled Down from Isotropic Phase to Hexagonal PhaseUnder Oscillatory Shear

Shear Stress Amplitude: 500 PaFrequency: 5 Hz

ID02 BeamlineESRF, Grenoble, France

Oscillatory Shear

with T. Narayanan

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Shear-Induced Alignment of p-SWNT/C12E5/D2O

(Radial) (Tangential)

Lim and Choi et al, Angew. Chem. Int. Ed. 53, 12548 (2014)

+

Hexagonal Array in Honeycomb Lattice

AB2-Type

Lim and Choi et al, Angew. Chem. Int. Ed. 53, 12548 (2014)

5.0 nm 4.4 nm

• Maximization of Free Volume Entropy

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C12E5/water

Binary Superlattice of 1D Nanoparticleswith Varying Diameter Ratio

4.4 nm

Polymerized Rod-like Nanoparticle

p-CnTVB

10-3

10-2

10-1

100

101

102

103

104

Scat

teri

ng I

nten

sity

(a.u

.)

4 5 60.1

2 3 4 5 61

2 3 4

q(nm-1

)

n=16D=3.9 nm

n=14D=3.4 nm

n=12D=3.0 nm

n=10D=2.6 nm

n=8D=2.1 nm

No. of CarbonDiameter

SANS Form Factor Analysis

p-CnTVB

+

Variation of Diameter Ratio at a Fixed Concentration

Without p-CnTVB

(F127/water=45/55)

With p-CnTVB (10/45/55)

0.910.800.680.59 Rrod/RC12E5

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10/45/55

Variation of p-CnTVB Concentration (for n=10)

p-C10TVB/C12E5/Water (X/45/55)

9/45/55

8/45/55

7/45/55

6/45/55

Diameter Ratio = 0.59

5/45/55

T= 4℃10/45/55 5/45/55

10/45/55

Variation of p-CnTVB Concentration (for n=10)

p-C10TVB/C12E5/Water (X/45/55)

9/45/55

8/45/55

7/45/55

6/45/55

Diameter Ratio = 0.59

5/45/55

T= 4℃10/45/55 5/45/55

deuterated p-C10TVB

+

CM C12E5/Water

Contrast matched SANS

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AB2 to AB3 Structural Transition

p-C10TVB/C12E5/Water (X/45/55)

Diameter Ratio = 0.59

T= 4℃

AB2-TypeHexagonal Array in “Honeycomb Lattice”

AB3-TypeHexagonal Array in “Kagome Lattice”

SH Lim, T. Lee, Y. Oh, T, Narayan, BJ Sung, and SM ChoiNature Communications (accepted)

SH Lim, T. Lee, Y. Oh, T, Narayan, BJ Sung, and SM ChoiNature Communications (accepted)

In collaboration with Prof. Bong Jun Sung

Theoretical Free Energy Calculations and Phase Diagram

Free energyTheoretical

Phase DiagramExperimental

Phase Diagram

p-CnTVBs and C12E5 are modeld as 2D hard discs A and B of different effective diameters.

2017-07-04

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Summary

AB2-Type AB3-Type

• Small angle neutron and x-ray scattering techniques are very powerful for studying soft matter.

2

)()(

rderQd

d rQisld

1

Neutron Spin Echo Investigations of Lipid Membranes Interacting with Proteins

Sung-Min Choi

Neutron Scattering and Nanoscale Materials Lab.Dept. of Nuclear and Quantum Engineering

KAIST

Antonio Faraone (NIST) Philip A. Pincus (UCSB)Steven R. Kline (NIST)

Ji-Hwan LeeChangwoo Do (now at ORNL)Shin-Hyun KangMin-Jae Lee

Collaborators

D. M. Engelman, Nature, 438, 578 (2005)

Cell Membranes

2

Reynwar B.J. et al, Nature 447 (2007)

Interplay of Proteins and Lipidsdetermines the Shape and Function of Cell Membranes

• To create shapes and functions, membranes must undergo deformations • The work to deform membranes is determined by

the structure and elasticity of the membrane.

Zimmerberg J et al, Nature Rev.: Mol. Cell Bio. 7,9 (2006)

Antimicrobial Peptide Activity in Multicellular Organisms

E. coli treated with an Antimicrobial Cationic Peptideat low concentration (left) and at high concentration (right).

www.cmdr.ubc.ca/cool.html

• Provides the self-defense mechanism of plants and animals

3

Transmembrane Pore-Forming Models

K. A. Brogden, Nature Rev. MicroBiol. 3, 238 (2005)

L. Yang et al, Biophys. J. 21, 1475 (2001)

Antimicrobial Peptide-Membrane Interaction

P/L = Peptide-Lipid molar ratio

(P/L)*Pores are formed

H.W. Huang et al, Phys. Rev. Lett, 92, (2004)

Thermal Fluctuation of Membrane Interacting with Peptides

Add more peptides

How does the elasticity of membrane changes with P/L (pore formation) ?

???

M.T. Lee et al, Biochemistry 43, 3590 (2004)

4

Model System

Melittin• A cationic peptide from European bee venoms• Forms toroidal pores in membrane

~3.5 nmL. Yang et al, Biophys. J. 21, 1475 (2001)

Toroidal Pore

~4 nm

~7.7 nm

DOPC• 1,2-Dioleoyl-sn-glycero-3-phosphatidylcholine• low gel-to-fluid temperature (Tm = -20°C)

~ 3.7 nm

• Prepared by extrusion through polycarbonate filters (100 nm)

• 10 mM Hepes 150 mM NaCl 2 mM EDTA D2O buffer solution

(P/L)*= ~0.4 %

Unilamellar

ca.100 % Perforated

50

40

30

20

10

031P

-NM

R I

nte

nsi

ty R

atio

(%

)

2.01.51.00.50.0

(P/L ) (%)

When are the pores formed ? 31P-NMR Signal Intensity vs P/L

5

6 mM DOPC + Melittin in 10mM Hepes 150 mM NaCl 2 mM EDTA D2O buffer.

For P/L = 0/100 – 20/100 were measured at ~ 6hrs after melittin-mixing.

SANS Data were analyzed using the polydisperse spherical core-shell model.

Spherical Core-Shell model analysis

Vesicle Structure vs P/L : SANS

2

1 13 ( ) ( ) 3 ( ) ( ( )). .( ) c c s c s s solv s

s c s

V J qR V J q RVol fracP q

V qR qR

SANS Measurements

10-4

10-3

10-2

10-1

100

101

102

103

104

105

106

107

108

109

1010

1011

1012

I(q)

80.001

2 4 6 80.01

2 4 6 80.1

2 4

q(Å-1)

Melittin / 6mM DOPC

P/L=0/100P/L=1/100P/L=3/100P/L=5/100P/L=8/100P/L=12/100P/L=14/100P/L=16/100P/L=20/100

Sensitive to single membrane dynamics

(qR >> 1)

Measured at NG7 SANS NIST

Neutron Spin Echo Spectrometer (NG7 NSE, NIST)

6

3/2)(exp)0,(

),( q

qI

qI

Zilman and Granek , Phys. Rev. Lett., (1996)

32/1

025.0)( qTkTk

q BBk

Neutron-Spin Echo Measurements

• Intermediate dynamic structure factor of membrane at large Q which is sensitive to single membrane dynamics.

Zilman and Granek Model

(qR >> 1) = Bending modulus

)(qNeutron Spin-Echo Intensity

= Solvent viscosity

M.C. Watson and F.L.H. Brown, Biophys. J. (2010)

Elasticity of Lipid Bilayers Interacting with Melittins

32/1

~025.0)( qTkTk

q BBk

kd 2~

For a pure DOPC bilayer

J.-H. Lee, S.M. Choi, C. Doe, A. Faraone, P. A. Pincus, S.R. KlinePhys. Rev. Lett., 105, 038101 (2010)

Tkq

q

B

3

)(~

7

Change of Bending Modulus UponPerturbation of Local Chain Packing by Peptide Adsorption

Pure Membrane

6

8

10

12

Mixed Membrane (12 + 6)

Effect of Chain Packing Disordering on Bending Modulus

Szleifer et al, Phys. Rev. Lett. 60 (1988)

Surfactant Bilayer

Be

nd

ing

Mo

du

lus

Bending Modulus vs P/L

Region I : a) Membrane thinning (ca. -0.7 kBT)

b) Perturbation of hydrocarbon chain packing (dominant)

Region II : a) Membrane thickening (ca. +0.8 kBT)

b) High rigidity of pore forming melittins

Region III : ??

50

40

30

20Ben

din

g r

igid

ity

( k

BT

)

43210P/L (%)

P/L*

II IIII

8

Pore patchBound patch

or

or = Outer radius of a pore patch

= 3.9 nm

Yang et al, Biophy. J. (2001)Huang, J Phys II France (1995)

= Range of deformation

=

= 2.5 nm (DOPC)

(16h2κ/κa)

1/4

Membrane mediated interaction between pores

When the deformed membrane regions become overlapped, the membrane-mediated repulsive interaction between patches become significant.

50

40

30

20Ben

din

g r

igid

ity

( k

BT

)

43210P/L (%)

P/L*

Bending Modulus vs P/L

Region I : a) Membrane thinning (ca. -0.7 kBT)b) Hydrocarbon chain disordering (may be more dominant)

Region II : a) Membrane thickening (ca. +0.8 kBT)b) High rigidity of pore forming melittins

Non-interacting orweakly interacting

Interacting patches

Region III : Strong interaction between pore patches

7.7 nm

(P/L) Inter-pore distance

2 % 12 nm 4 % 7.9 nm

I II III

J.-H. Lee, S.M. Choi, C. Do, A. Faraone, P. A. Pincus, S.R. KlinePhys. Rev. Lett., 105, 038101 (2010)

9

Summary

• The thermal fluctuation and elasticity of DOPC vesicles interacting with pore-forming melittins has been measured by the Neutron Spin-Echo Spectroscopy,for the first time.

• The change of thermal fluctuation and elasticity with (P/L) was understood in terms of membrane thinning and thickening, chain packing perturbation and inter-pore interaction.

• The change of elasticity of DMPC-gD, DLPC-gD with (P/L), covering repulsive and attractive interaction ranges, has been investigated for the first time.