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