Vibrational Sum Frequency Generation Studies of Self Assembled Monolayers on Gold for Biological Functionalization Achani K. Yatawara Department of Chemistry.

Vibrational Sum Frequency Vibrational Sum Frequency Generation Studies of Self Generation Studies of Self

Assembled Monolayers on Gold for Assembled Monolayers on Gold for Biological FunctionalizationBiological Functionalization

Achani K. YatawaraDepartment of Chemistry

h1

h2h3

SAMs for Bio-SAMs for Bio-functionalizationfunctionalization(I ) Amino/Carboxy t-SAMs- Neuron (I ) Amino/Carboxy t-SAMs- Neuron

AdhesionAdhesion

(II) a. Maleimide t-SAMs(II) a. Maleimide t-SAMs

b. Aldehyde t-SAMsb. Aldehyde t-SAMs

Surface modification Chemistry Surface modification Chemistry

-Alkanes (thiol/amines)-Alkanes (thiol/amines)

-Sugars-Sugars

-Amino acids-sugars-Amino acids-sugars

SFG techniqueSFG technique

|v=0

|v=1

IR

vis SFG

(2) (2)

0

( ) ( ; , ) ( ) ( )SFG SFG IR vis IR IR vis vis IRP E E d

2(2)( ) ( )SFG SFG SFGI P

2nd order NL susceptibility

SFG 2nd order NLO technique Specifically used to study surfaces and interfaces (no-bulk contribution) Sub-monolayer sensitivity Molecular structure, conformation and orientation

2(2)SFGI P

IRvisSFG

SFG

vis

IR

Surface Polarization P (2)

So

P

Frequency domain-BB Vibrational SFG

IR

IRvis

vis

SFG= IR+ vis

S()

I. I. SAMs for Neuron SAMs for Neuron ImmobilizationImmobilization

FI

VSFGVSFG S. H. Scott, Nature, 2006NH2

NH2

NH2

NH2

NH2

NH2

NH2

COOH

COOHCOOH

COOH

COOH

COOH

COOH

COOHCOOH

COOHNH2

NH2

NH 2

NH2

Hochberg et al. Nature, 2006

AFM

25x103

20

15

10

5

0

SF

G in

tens

ity

(a.u

.)

3000290028002700

IR frequency (cm-1

)

Ra =1.918 nm

Gold type AGlass

40nm Cr (0.5 nm/s)

400nm Au (1.0 nm/s)

gold type A with PPP polarization

2

v vvIR

vviNRIRSF i

bea

dFRd

d

Experimental Experimental approach for approach for molecular molecular structure structure determination determination of SAMsof SAMs C-H Stretch regionC-H Stretch region

12

10

8

6

4

2

0

Nor

mal

ized

SF

G in

tens

ity

(a.u

.)

30002950290028502800

IR frequency (cm-1

)

Carboxy t- SAM

mix SAM

Amino t- SAM

d COOH

COOHCOOH

COOH

COOH

COOHCOOH

NH2NH2

NH2

NH2

NH2

NH2

NH2

COOHCOOH

COOH NH2

NH2

NH 2

NH2

SAM on Au

Au

C-H Stretch C-H Stretch regionregion

gold type B with PPP polarization

Ra = 0.714 nm

Gold type BGlass

5 nm Cr (0.1 nm/s)

50 nm Au (0.1 nm/s)

8

6

4

2

0Nor

mal

ized

SF

G in

tens

ity

(a.u

.)

30002950290028502800

IR frequency (cm-1

)

Carboxy t- SAM

Amino t- SAM

mix SAM

FRd dd COOH

COOHCOOH

COOH

COOH

COOHCOOH

NH2NH2

NH2

NH2

NH2

NH2

NH2

COOHCOOH

COOH NH2

NH2

NH 2

NH2

Ra = 0.852 nm

Gold type CGlass

C-H Stretch C-H Stretch regionregion

gold type C with PPP polarization

20 nm Cr (0.1 nm/s)

100 nm Au (0.1 nm/s)

12

10

8

6

4

2

0Nor

mal

ized

SF

G in

tens

ity

(a.u

.)

30002950290028502800

IR frequency (cm-1

)

Carboxy t- SAM

Amino t- SAM

mix SAM

dFRdd

d

COOHCOOH

COOH NH2

NH2

NH 2

NH2

NH2NH2

NH2

NH2

NH2

NH2

NH2

COOH

COOHCOOH

COOH

COOH

COOHCOOH

Significant amount of Gauche defects disordered

monolayer

Frequencies methylene d+

(~2855 cm-1), d-

(~2925 cm-1)”liquid-like” alkane

chains

Vd+ cm-1

Liq. 2855

Solid 2850

Vd

- cm-1

Liq. 2924

Solid 2918

Conclusions-C-H Conclusions-C-H regionregion

Porter et. al. JACS 1987

Richter et. al. Opt. Lett. 1998

C=O stretch C=O stretch regionregion

H-bonded COOH and mix SAMs

Mix SAM-no separate domains COOH and amino

Conclusions-C=O regionConclusions-C=O region

0.5

0.4

0.3

0.2

0.1

0.0Nor

mal

ized

SF

G in

tens

ity

(a.u

.)

18001750170016501600

IR frequency (cm-1

)

CO

O

HHC

OO

mix SAM - gold type A

mix SAM - gold type B

COOH SAM - gold type A

COOH SAM - gold type B

Results After Neuron Results After Neuron Immobilization on SAMsImmobilization on SAMs

Fluorescent microscopic Images

Overall Overall conclusionsconclusions Neutron attach & grow well on amino t-SAMs, and do not

attach to COOH/Mix SAMs Neuron adhesion is not critically affected by the surface

roughness or details of the molecular ordering and orientation of the terminal amino groups

Neuron adhesion and growth depend mostly on the chemical functionality displayed at the surface

Amino t-SAMs-gold C

Amino t-SAMs-gold A

Amino t-SAMs-gold B

Mix SAMsCarboxy t-SAMs

PDL

II. SAMs for Surface Chemical II. SAMs for Surface Chemical ModificationsModifications

(a) Modifications of Maleimide t-SAMs

(b) Modifications of Aldehyde t-SAMs

HS

R H2N

R

NaBH3CN pH ~10

Au

N

HN

O

O

O

S

N

HN

O

O

O

S

R

S

Au

NH

S

RH

O

SAu

Au

II a. Maleimide t-SAMs Surface II a. Maleimide t-SAMs Surface ModificationModification

1.8

1.6

1.4

1.2

1.0

Nor

mal

ized

SF

G in

tens

ity

(a.u

.)

320031003000

IR frequency (cm-1

)

C11 -gluc

N

HN

O

O

O

S

HH

Au

Maleimide t- SAM

C16-gluc

Cys-gluc

C6-thiol

3070 cm-13130 cm-1

1.1

1.0

0.9

0.8

0.7

0.6

0.5N

orm

aliz

ed S

FG

inte

nsit

y (a

.u.)

180017601720

IR frequency (cm-1

)

1728 cm-1

1746 cm-1

NO

O

Before After

NO

O

Maleimide t-SAM

After

Surface covalent attachments are successful

Unsaturated C-H stretch Unsaturated C-H stretch region and C=O stretch regionregion and C=O stretch region

Saturated C-H stretch Saturated C-H stretch regionregionStep 1Step 1: Preparation of maleimide t- SAMs on gold

Step 2Step 2: Modification with a) C6 thiol

Au

48 hr, RT

Au

N

HN

O

O

O

S

N

NH

O

O

O

S

N

HN

O

O

O

S

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5Nor

mal

ized

SF

G in

tens

ity

(a.u

.)300029002800

IR frequency (cm-1

)

d r r

FRr

dMaleimide t- SAMs

C6-thiol

Au

H

S

H

H

N

HN

O

O

O

S

H

SH

H

H

Au

N

HN

O

O

O

S

48 hr, RT

Step 2Step 2: Modification with b) C11 -glucose c) C16 -glucose

O

HN

OH

HOHO

OHO

SH

OHN

OH

HOOHO

S

N

HNO

OO

S

HO

pH ~6.5 Au Au

N

HN

O

O

O

S

C16 -glucose

1.2

1.0

0.8

0.6

0.4

0.2Nor

mal

ized

SF

G in

tens

ity

(a.u

.)

300029002800

IR frequency (cm-1

)

d d

gluc-C-H

Maleimide t- SAMs

C11- gluc

C16 - gluc

Step 2Step 2: Modification with d) Cys -glucose

pH ~6.5

Au Au

N

HN

O

O

O

S

O

OHHO

OH

OH

NH

HN

SH

OH2N

O

O

OHHOOH

OH

NH

HN

S

N

O

OO

H2N

HNO

S

O

1.2

1.1

1.0

0.9

0.8

0.7N

orm

aliz

ed S

FG

inte

nsit

y (a

.u.)

300029002800

IR frequency (cm-1

)

dd

gluc-C-H

Cys-gluc

Maleimide t- SAMs

II b. Aldehyde t-SAMs Surface II b. Aldehyde t-SAMs Surface ModificationModification Saturated C-H stretch regionSaturated C-H stretch region

C6H15NH2, NaBH3CN pH~10

AuS

HN

HHH

Au

48 hr, RT

HO

S

HO

S

Au

HO

S

Au

HO

S

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

Nor

mal

ized

SF

G in

tens

ity

(a.u

.)

3000295029002850

IR frequency (cm-1

)

FRrr

d

rFRd

d

Aldehyde t-SAM

After

AcknowledgmentAcknowledgmentProf. Alex

Benderskii

Group membersDr. Andrey BordenyukDr. Igor StiopkinHimali JayathilakeChampika WeeramanFadel ShalhoutAdib Samin

CollaboratorsProf. Gregory W. Auner Smart Sensors and Integrated Microsystems (SSIM), Department of Electrical and Computer Engineering and Department of Biomedical Engineering -WSUDr. Olena Palyvoda

Prof. Peter Andreana, Department of Chemistry –WSUDr.Gopinath Tiruchinapally

WSU start-up grantWSU research grantNano@Wayne

ACS-PRF NSF CAREER

Funding