Department of ChemistryPohang University of Science and Technology

Hee Cheul Choi

Electrical Sensing of Biomoleculesbased Nanomaterials

and Carbon Nanotubes

Specific Protein Binding Sensor using SWNT (case 1)

Star. A, et al. Nano. Lett. 2003, 3, 459PEI & PEG

AFM image

CNT w/ Protein

Protein Sensor using SWNT (case 2)

Boussaad. S, et al. Chem.Comm. 2003, 1502.

Individual SWNT device

CE : Pt RE : Ag/AgCl

A,B : #1 & #2 : p-type, #3 : metallic SWNTC : before D & E : after the introduction of

the protein(cytochrome c) sol’n

P-type SWNT

PBS

(200 μM)Protein adsorption does not change slop but VTh

Specific Protein Binding Sensor using SWNT (case 2)

Chen. R, J, et al. PNAS. 2003, 100, 4984Besteman. K, et al. Nano. Lett. 2003, 3, 727

O2H2O2(GOx)

glucose

gluconic acid

AFM image

Linking molecule: pyrene group

Glucose Sensor using SWNT

Specific Protein Binding Sensor using SiNW

Cui. Y, et al. Science 2001, 293, 1289

biotin-modified SiNW streptavidin

1, 3 : buffer 2 : 3 μM m-antibiotin

Unmodified SiNWModified SiNW

↑ 1, 3 : buffer 2 : 250 nM streptavidin

Modified SiNW

1 : buffer 2 : bovine IgG3 : 3 μM m-antibiotin

G(nS)

DNA Sensor using SiNW

Hahm. J, et al. Nano. Lett. 2004, 4, 51

(A) Yellow : sensor deviceGreen : microfluidic channel

(B) PNA(peptide nucleic acid) surface(C) PNA-DNA duplex

1 : buffer2 : 60 fM WT DNA →

1,3 : DNA free sol’n2,4 : 100 fM MU DNA ↓

Static system Flowing (buffer) system

Single Virus Sensor using SiNW

Patolsky. F, et al. PNAS. 2004, 101, 14017

Microfluidic Channel (100 virus particles per μl)

Influenza A virus

anti-hemagglutinin for influenza Aanti-adenovirus group Ⅲ

anti-influenza type A antibodyanti-adenovirus group antibody Introduce 1: adenovirus

2 : influenza A3 : buffer4 : 1 : 1 mixed adenovirus

& influenza A

50 virus particles per μl

Single Virus Binding Selectivity

Park. S, et al. Science 2002, 295, 1503

Application 2 : DNA array detection

Res

ista

nce

(ohm

s)

Part Ⅱ

What applications carbon nanotubes will contribute?

Field emission devices

Electromagnetic Shield coating

Strong materialsRay Baughman, UT Dallas

Diamond C60

Graphite Carbon nanotube

Forms of Carbon

Structure of carbon nanotubes

Graphite

• Nanotubes consist of graphenesheets of carbon

Single-walled nanotube (SWNT)

• Rolled into a cylinder

Multi-walled nanotube (MWNT)

• Some with multiple concentriccylinders

Multi-walled (MWNT) Single-walled (SWNT)

Sumino Iijima Richard Smalley

SWNTs are all C molecular wires and excellent quasi 1D systems for basic work (synthesis, materials science and physics) and potential applications

Representatives of carbon nanotubes

Nanotubes at various stages of growth

• Particle size ~ tube diameter• Catalytic particles (active end) remain on support• The other end is dome-closed • Base growth (differs from the VLS growth mode)

How do SWNTs grow?Diameter Control: Catalytic Nanoparticles

Derived in Apoferritin Templates (d~1-3 nm)

Y. Li, et al.,J. Phys. Chem., 105, 11424, 2001

SubstrateSubstrate

G6OH PAMAM Fe(III)/G6OH PAMAM

Calcination CVD growth

Fe2O3

Sorption of Fe(III)

Diameter Control: Catalytic NanoparticlesDerived in Dendrimer Templates (d~1-2 nm)

Choi, H. C. et. al J. Phys. Chem. B 2002, 106, 12361.

5 nm

1 mm

10 nm

1.3 nm250 nm

• Diameters: 1-2 nm• (1-5 nm with conventional supported catalyst)

CVD

Fe2O3 Nanoparticle on SiO2

Nanotubes Grown From Dendrimer Templated Nanoparticles

OH OH OHCalcination

Iron oxide nanoparticleFe(III) NH2OH

500 nm

SiO2 SiO2

250 nm

A Simple Approach to Monolayer Catalytic Nanoparticles: Clean Tube Films

Choi, H. C. et al., Nano. Lett. 2003, 3, 157.

1 μm

Applications

• AFM tip for high resolution images and fabrication• Electrical devices• Electro-mechanical devices• Gas and biosensors

Nature 398,761-762, 1999PNAS 97, 3809-3813, 2000

J. Am. Chem. Soc. 120, 603-604 (1998)

Immunoglobin G (IgG)- consists of 4 polypeptide chains (Y-shpe)- Two antigen binding fragments (Fab)- One Fc site

SWNT MWNT

Nanotube at the apex of Si tip- Direct growth for SWNT- Glue attached for MWNT

For better resolution Tube deflection and Conductance change

Deflection and corresponding conductance changes: “reversible”

P-type silicon wafer

500 nm - 2 mm SiO2

HP4156 Semiconductor Analyzer

VsVdVg

SWNTTi/Au

Carbon nanotube based Field Effect Transistors (SWNT-FETs)

10 mm1 mm

VSD

30

25

20

15

10

5

0

I(nA

)

-10 -5 0 5 10Vg(V)

Applied bias = 10 mV

I-Vg characteristics of SWNT-FETs

-Vg

- - - - -iSD

+ + + + +

+Vg

Mo

SiO2

Si

W

Integrated Nanoelectronics: NanotubeTransistor Arrays with Local W/ SiO2 gates

Wgate

S

D

50 µm

500 µm

Derived by patterned growth of nanotube arraysPercentage of semiconducting tubes: ~ 70% by CVDHigh yield of transistorsAbility in obtaining p- and n- arrays on same chip forComplementary Devices

Vout

VDD

p

p

p

n

n

n

-2.5

-2.0

-1.5

-1.0

-0.5

V out (

volts

)

3020100Time (ms)

-1.5

-1.0

-0.5

0.0

Vou

t (vo

lts)

806040200

Time (s)

0,0 0,1 1,1 1,0

AND gateVDD

A

B

n

n

pp

Vout

np

Nanotube Ring Oscillators & Logic Gates

Javey et al. Nano Lett., 2002

• Orders of magnitude conductance response

• Room temperature

• NO2: near chemisorption

• NH3: physisorption

Science, 287, 622, 2000

Nanotube Chemical Sensors

H2 sensing with SWNT/Pd single device

~ 5 Å Pd

J. Kong et. al., Adv. Mater. 13, 1384, 2001

Nanotube sensor array with 100% yield

• Grow multiple tubes for each device in a large array

• Semiconducting tubes dominant (70%)

• Excellent electrostatic gating and chemical gating sensitivity

• Large sensor arrays obtained (100% yield, low noise)

300μm

40μm

4μm

3.0

2.5

2.0

1.5

I(μΑ

)

-10 0 10Vg (V)

0.5

0.4

0.3

0.2

0.1

0.0

-ΔG

/G0

80006000400020000t(s)

100ppt

200500

1ppb

2

0.5

0.4

0.3

0.2

0.1

0.0

-ΔG

/G0

-20-100Vg (V)

0.5

0.4

0.3

0.2

0.1

0.0

108642[NO2](ppb)

4.0

3.5

3.0

2.5

I(μΑ

)

-10 0 10Vg (V)

Enhanced sensitivity of NO2 detection for polymer (PEI) coated n-type devices

Enhanced selectivity as well:No response to NH3, CO, CO2, H2, CH4, O2

I-Vg of n-type device

• NO2 sensing:Down to 100 pptsensitivity

• Sticking coefficientPEI/tube ~ 0.3No PEI/tube ~0.001

8

7

6

5

4

3

2

I(μΑ

)

160012008004000t(s)

NH3100ppm

NH3500ppm

NO21ppm

Multiplex-functionalized sensor array capable of detecting multiple molecules in a gas mixture

PEI coated

Nafion coated

• Micro-spotting used for coating different devices with different polymers

Nafion coated

PEI coated

P. Qi, et al, Nano Lett. 3, 347, 2003

- Change of IDS by the effect of VGS- VGS by electric field

Conventional CNT-FET

CNT-Chemical Effect Transistor (CET)- Change of IDS NOT by the effect of VGS- Why not by chemical effects?

* Charge transfer from molecules to CNT

CNT-FET as a smart sensor

Bias (V)

Counter electrode (Pt)Reference electrode (Ag/AgCl)

-Teflon based electrochemical cell-

200 μm

50 μm

5 μm

CNT-FET device for biosensor applications

100 nm

C

rinses

-200

-150

-100

-50

0

50

QC

M S

igna

l ΔF

(Hz)

1614121086420

t/103 (s)

1 μM Streptavidin

100 nM10 nM.1 nM

1 nM

(A

(B200 nm Turns out to be generic:

Streptavidin, Protein A, Glucosidase, Bovine Serum Albumin, IgG…

Chen et al, PNAS 2003, 100, 4984

Non-specific interaction of SWNT with proteins

A

OO

O

OO OHO

OOHO

OHw x

y

zOO

O

OO OHO

OOHO

OHw x

y

z

SA

E

IIIIII

B200 nm

repelled

-200

-150

-100

-50

0

50

QC

M Δ

F(H

z)

1612840t/10

3(s)

-200

-150

-100

-50

0

50

QC

M S

igna

l Δ

F (H

z)

543210

t /103(s)

C

.05% Tween 20

rinses

rinse100 nMSpA

100 nMBSA

100 nMSA

Non-covalent irreversible adsorption

Water solubility, highly stable

Protein resistant

Tween 20 & Pluronic block copolymer P103 are the best

Hydrophobic/vdW anchoring of Tween20/PEG

Selective electronic biosensor

Where does the conductance change come from?

• Nanotube aspects: – Charge injection from biomolecules– Electric double layer field modulation caused by

biomolecules

• Metal-nanotube contact aspect: – Adsorbed chemical species may modulate work function

level of contact metals, which consequently change the Schottky barrier height resulting in the conductance change.

Origin of the conductance change

S

OOMe

n

Pd/Au evaporation

mPEG-SH SAM

SiO2/Si

PMMA

SWNT

s

SiO2/Si

SiO2/Si

s s s s ss ss s ss s

SiO2/Sis s ss

Lift off

SiO2/Sis s ss

Tween 20

Lift offthen

SiO2/Si

Lift off

OO

O

OO OHO

OOHO

OH

w x

y

z11

S

OOMe

n

Device IIIDevice I

S

OOMe

nS

OOMe

n

Device II

Chen, Choi et al J. Am. Chem. Soc. 2004, 126, 1563

CNT-FET device fabrication

Both photolithography and electron-beam lithography can be used .02x10-6

3.00

2.98

2.96

2.94

I ds (μ

Α)

12008004000Time (s)

.50x10-6

1.48

1.46

1.44

I ds (μ

Α)

12008004000Time (s)

.40x10-6

3.30

3.20

I ds (μ

Α)

12008004000Time (s)

.50x10-6

3.45

3.40

3.35

3.30

I ds (

μΑ)

10008006004002000Time (s)

100 nM

BSA HIgG

Device IMetal-nanotube

Device IINanotube only

100 nM

100 nM100 nM

Nanotube vs. metal-nanotube contact

.50x10-6

2.40

2.30

I ds (μ

Α)

12008004000Time (s)

3.5x10-6

3.4

3.3

3.2

3.1

I ds (

μΑ)

800600400200Time (s)

.50x10-6 3.453.403.353.303.253.20

I ds (μ

Α)

12008004000Time (s)

.65x10-6

2.60

2.55

2.50

2.45

I ds (

μΑ)

12008004000Time (s)

hCG HSA

100 nM

100 nM

100 nM100 nM

Device IMetal-nanotube

Device IINanotube only

Nanotube vs. metal-nanotube contact

Effective functionalization of metal surface with appropriate chemical species will lead high sensitive and selective nanotube-biosensor.

Device I

Device II

S

OOMe

nS

OOMe

n

Pd or Au

Pd or AuS

OOMe

n

1. hCG NSB

1. mPEG-SH on Pd or Au

2. hCG NSB

Conductance (G) Measurement

G

G

Time (s)

Time (s)SiO2/Si

SWNT-FET

Summary of biomolecule sensing mechanism

Application 1 : DNA-templated CNT-FET

Keren. K, et al. Science. 2003, 302, 1380

DNA-templated CNT FET& metallic wires contacting it

DNA and Protein Sensor using GC/CNTs (case 3)

Wang. J, et al. J. Am. Chem. Soc. 2004, 126, 3010.

glassycarbonelectrode(GC)

CNT

DNA protein

Chronopotentiometric signals

SEM image

Magnetic beads-DNA-CNT + 10 pg/mL target sample

A (DNA) : 10 pg/mL target oligonucleotideB (protein) : 80 pg/mL IgG(a) single ALP tag(b) CNT-multiple ALP tags(c) CNT-ALP tags modified GC electrode

50 μL α–naphthyl PBS sol’n(50 mM) w/ enzymatic rxn