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The Chemistry of Single Walled Carbon NanotubesApplications to nanotube separation and biomolecule detection
The Chemistry of Single Walled Carbon NanotubesThe Chemistry of Single Walled Carbon NanotubesApplications to nanotube separation and Applications to nanotube separation and biomoleculebiomolecule detection detection
Michael S. StranoDepartment of Chemical and Biomolecular Engineering
University of Illinois at Urbana-Champaign
Michael S. StranoMichael S. StranoDepartment of Chemical and Biomolecular EngineeringDepartment of Chemical and Biomolecular Engineering
University of Illinois at UrbanaUniversity of Illinois at Urbana--ChampaignChampaign
P. Barone, M. Usrey, D. Heller, E. Jeng, C. Lee, N. Nair, W. Kim, J. Choi
P. Barone, M. Usrey, P. Barone, M. Usrey, D. Heller, E. Jeng, C. Lee, N. Nair, W. Kim, J. ChoiD. Heller, E. Jeng, C. Lee, N. Nair, W. Kim, J. Choi
OutlineOutline
(n,m) selective, covalent chemistry of single walled carbon nanotubes
• Mechanism of electronic sensitive reactions
• Separation and sorting carbon nanotube by electronic type
Single walled carbon nanotubes as near infrared fluorescent biosensors
• Nanotube sub-cellular “molecular beacons”
• Tissue implantable biomedical devices
(n,m) Selective Chemistry on SWNT(n,m) Selective Chemistry on SWNT
e-
covalentreaction
ClNNF4B
Cl
Rate = f(n,m)+ R
R
Scalable (n,m) Separation Method
Exploitation of functional group for preparative scale (n,m) separation Metals
SemiconductorsFunc. Metals
SemiconductorsFunc. Metals
+
Semiconductors
On-chip Modification of SWNT FETs
SWNT FET Array
Functionalization carried out directly on SWNT array• ON / OFF current approaches 105
An, L., et. al. J. Am. Chem. Soc. 2004, 126, 10520.Balasubramanian, K., et. al. Nano Lett., 2004, 4, 827.Wang, C., et. al. J. Am. Chem. Soc. 2005. 127, 11460.
Before Rxn
After Annealing1st Rxn74% OFF state current
2nd Rxnzero OFF state current
Before Rxn
After Annealing1st Rxn74% OFF state current
2nd Rxnzero OFF state current
Semi-conductors
metals
M. S. Strano, C. Dyke, M. Usrey, el. al. Science 301 (2003) 1519-22
selective
UV-vis-nIR Absorbance190 to 1800 nmRaman Spectrometer
532 nm excitation
Stirred 3 neck flask70 mL of aqueous dispersed SWNT1% SDS/D2O ~ 10 mg SWNT/L
Peristaltic pump
Spectrophotometer
SampleRecirculation
Reaction Vessel at 25 oC
ClNNF4B
Reagent
0.25 mg/mlAdded in 100 μL aliquots
unreacted
reactedDisorder mode
Monitor Bond Formation
H2O dispersed
reacted in DMF
Monitor Charge Transfer
ML Usrey et al: JACS, 127 (2005) 16129-35.
Apparatus for Studying SWNT ChemistryApparatus for Studying SWNT Chemistry
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
300 800 1300 1800Wavelength (nm)
Abs
orba
nce
Ener
gy
1% SDS/D2O, 28 mg/L exposed to air
(9,1)(13,3)
Absorption Spectrum Allows Probing of Valence Electrons
Ener
gy
Density of States
Semiconductingv1→c1
v1
c1Semiconducting
v2→c2
v2
c2
v1
c1
Metallicv1→c1
0.45
0.55
0.65
0.75
0.85
400 600 800 1000 1200 1400 1600
Wavelength (nm)
OD
0.63
0.67
0.71
0.75
480 580 680
4 00
W a v e le n g th (n m)
0.02.13.95.69.111.8
aryl chlorideSide groups x 103
/Carbons
v1→c1 Metaltransitions
v2→c2 Semiconductor transitions
v1→c1 Semiconductor transitions
Low Concentration: Selective Reaction of Metallic Nanotubes
M. S. Strano, C. Dyke, M. Usrey, el. al. Science 301 (2003) 1519-22
ClNNF4B
Two Step Mechanism from Raman SpectroscopyTwo Step Mechanism from Raman Spectroscopy
0.9
0.95
1
1.05
0 1 2 3 4 5
Time (hrs)
Rel
ativ
e In
tens
ity
1150 1350 1550 1750
Tangential mode after addition
Looks like A → B → C
Measures electron withdraw
Raman shift (1/cm)
Reagent addition
0
0.4
0.8
1.2
1.6
2
0 1 2 3 4 5
Time (hrs)
Rel
ativ
e In
tens
ity
Disorder mode after addition
Measures sp3 “disorder” ∴covalent bond formation
Reagent addition
B
C
Cl
N2+
(A)
(B)
(C)
k1
k-1k2
θ = θT – B[t] – C[t]
ClθA B C+
If coverage remains sparse, θ[t] >> (B[t] + C[t], k-1 ~ 0
k1
k-1
k2
0.9
0.95
1
1.05
0 1 2 3 4 5
Time (hrs)
Rel
ativ
e In
tens
ity
0
0.4
0.8
1.2
1.6
2
0 1 2 3 4 5
Time (hrs)
Rel
ativ
e In
tens
ity
Resolves outstanding problems:k1 = selective and delocalizedk2 = follows Pyramidalization
Disorder Mode “C”Tangential Model “B”
Understanding the Selective MechanismUnderstanding the Selective Mechanism
ML Usrey, ES Lippmann, MS Strano: JACS, 127 (2005) 16129-35.
Sodium dodecyl sulfate surfactant beads
Reagent is accessible
Sodium cholate:
closely packed adsorbed phase;steric hindrance
A → B → CX
0.8 nm
0.3
0.5
0.7
0.9
1.1
1.3
1.5
1.7
600 800 1000 1200 1400 1600Wavelength (nm)
OD
051520304060-150D
opin
g Ti
me
(min
)
\12-02-04 Cholate Doping 5sx5.HOL
1100 1200 1300 1400 1500 1600 1700
2000
4000
6000
8000
10000
12000
14000
16000
Raman Shift (1/cm)
Coun
ts
2468
10121416
Rel
ativ
e In
tens
ity
Raman Shift (cm-1)1100 1200 1300 1400 1500 1600 1700
\12-02-04 Cholate Doping 5sx5.HOL
1100 1200 1300 1400 1500 1600 1700
2000
4000
6000
8000
10000
12000
14000
16000
Raman Shift (1/cm)
Coun
ts
2468
10121416
Rel
ativ
e In
tens
ity
\12-02-04 Cholate Doping 5sx5.HOL
1100 1200 1300 1400 1500 1600 1700
2000
4000
6000
8000
10000
12000
14000
16000
Raman Shift (1/cm)
Coun
ts
\12-02-04 Cholate Doping 5sx5.HOL
1100 1200 1300 1400 1500 1600 1700
2000
4000
6000
8000
10000
12000
14000
16000
Raman Shift (1/cm)
Coun
ts
2468
10121416
Rel
ativ
e In
tens
ity
Raman Shift (cm-1)1100 1200 1300 1400 1500 1600 1700
D Peak
G Peak
Fluorescence
Disorder Mode – no change
Tangential mode adsorption step still selective
Rea
ctio
n Ti
me
Further Evidence: Blocking the Second StepFurther Evidence: Blocking the Second Step
ML Usrey, ES Lippmann, MS Strano: JACS, 127 (2005) 16129-35.
metallic
semi-conducting
surfactant/H2O25 oC
e-
ClNNF4B
metallic
semi-conducting
metallic
N2
metallic
semi-conducting
metallicSelective Reaction
thermal
annealing
restoredmetallic
Separationprocessp-hydroxy benzene diazonium
OH
R
R
Electrophoresis
OH
O-
pH ~ 11
H+
Usrey, M. A., Strano, M. S., in preparation (2006)
Chemistry for Sorting Carbon NanotubesChemistry for Sorting Carbon Nanotubes
00.14
0.480.34DiazoniumAdded (mM)
10001500 2000
25003000
Raman Shift (cm-1)
Inte
nsity
(A.U
.)
D Peak
G Peak
G’ PeakPL
Chemistry Controls Electrophoretic MobilityChemistry Controls Electrophoretic Mobility
(+) Cathode
(-) Anode
ν = (q/f ) E
wells
ν= electrophoretic mobilityq = net charge
f = hydrodynamic factorE = applied electric field
ν
(-)
(+)
(-)
(+)
MW Std 0.48mMol
0.34mMol
0.14mMol
0mMol
No rxnCompleterxn
RO-
RO-
OutlineOutline
(n,m) selective, covalent chemistry of single walled carbon nanotubes
• Mechanism of electronic sensitive reactions
• Separation and sorting carbon nanotube by electronic type
Single walled carbon nanotubes as near infrared fluorescent biosensors
• Nanotube sub-cellular “molecular beacons”
• Tissue implantable biomedical devices
0
2
4
6
8
10
400 650 900 1150 14000
0.2
0.4
0.6
0.8
1
Wavelength (nm)
Abs
orba
nce
(cm
-1)
Norm
alized Fluorescence
SWNT Fluorescence
Blood Abs.
Water Abs.
Semi-conducting single walled carbon nanotubes
• fluoresce in near infrared• very photostable• sensitive to environment
D. A. Tsyboulski, Nano Lett., Vol. 5, No. 5, 2005
Advantages for Optical SensingAdvantages for Optical Sensing
Single nano-particle spectroscopy = single molecule sensor
(+ -) (+ -)Analyte
Scheme for β-d-Glucose SensorScheme for β-d-Glucose Sensor
Step I: Immobilization of binding site (GOx) on SWNT
+ (GOx)Self assembly Colloidally stable
Nanotube-Glucose oxidasecomplex
Glucose oxidase
Glucose + O2 + H2O H2O2 + 1,5-gluconolactone(GOx)
Step II: Coupling to electron transfer
2[Fe(CN6)]3- + H2O2 2[Fe(CN6)]4- + 2(H+) + 2e- + O2
Ferricyanide Ferrocyanide
A nanotube redox couple:
+ e- [ ]- Decrease influorescence intensity
Two Step SynthesisTwo Step Synthesis
PW Barone, S Baik, DA Heller, MS Strano: Nature Materials 4 (2005) 86-92.
Cryo-TEM of individual nanotubes
Band-gap fluorescence
50 nm
Step I: Immobilization of GOx EnzymeStep I: Immobilization of GOx Enzyme
Add1:200
Glucose Oxidase
SurfactantDialysis
440 nm
GOx-SWNT4.5 nm1
0123456
0 200 400 600 800Translation (nm)
Heig
ht (n
m)
1. Saal, K. et al. Bio. Eng. 19, 195-199 (2002).
02468
10
870 920 970 1020
Wavelength (nm)
Inte
nsity
(a.u
.)In
tens
ity (a
.u.)
Start
GOx
Energy shift with Binding
Glucose oxidase (GOx)
β-D-glucose
excitation
N-IR fluorescence= surface bound Fe(CN)6
-3
= adsorbed H2O2
0.00
0.20
0.40
0.60
0.80
0 5 10Glucose concentration (mM)
Norm
aliz
ed F
luor
esce
nce
0.20
0.50
0.80
1.10
0 10 20
Time (min)
1.4 mM
2.4 mM4.2 mM
Rel
ativ
e In
tens
ity
Rel
ativ
e In
tens
ity
Time (min)
Step II: Functionalization with FerricyanideStep II: Functionalization with Ferricyanide
(6,5)
PW Barone, S Baik, DA Heller, MS Strano: Nature Materials 4 (2005) 86-92.
Tissue Implantable Biomedical SensorsTissue Implantable Biomedical Sensors
Porous dialysis capillary13 kDa MW cutoff
Enzyme/SWNTsolution
200 μm
Rel
ativ
e In
tens
ity5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
105
1 cm
EpidermalTissue
Sample
nIR image of filled capillary beneath tissue sample
Photodiode Laser InGaAs Array
Excitation
Emission
ImplantedCapillary
Tissue
PW Barone, RS Parker, MS Strano: Analytical Chemistry 77 (2005) 7556-62.
DNA Wrapped Carbon Nanotube HybridsDNA Wrapped Carbon Nanotube Hybrids
2 nmalternating guanine/thymine pairs – 20 mer
Raw material
ds(GT)15oligomers
Ultra-sonication3 W, 4 oC
Centrifugation
Synthesis I: Sonication
M Zheng, A Jagota, MS Strano, et al. Science 302 (2003) 1545-48.
1) 2) 3)
cholateDNA Probe 12-14kDa dialysis membrane
100kDa dialysis membrane
0
0.2
0.4
0.6
0.8
1
1.2
850 900 950 1000 1050 1100
wavelength (nm)
Nor
mal
ized
Inte
nsity
DNA-SWNT
Cholate SWNT
-17.6 meV
Fluorescence
Sodium cholate ssDNA
Synthesis II: Dialysis
E. Jeng, M. Strano, Nano Letters, ASAP (2006)
Selective Detection of DNA HybridizationSelective Detection of DNA Hybridization
Jeng, E.S., Strano, M.S. Nano Letters ASAP (2006) Graduate Student Esther Jeng
-0.5
0
0.5
1
1.5
2
2.5
0 500 1000 1500
[cDNA or nDNA] (nM)
ΔE
(meV
)
nDNA
cDNA
0.85
0.95
1.05
987 992 997
wavelength (nm)N
orm
aliz
ed
Inte
nsity
0nM879nM
cDNA2meV
hν1
hν1
hν3
hν2
Selective response to complement
cDNA = 5’- GCC TAC GAG GAA TTC CAT AGC T – 3’
5’ – TAG CTA TGG AAT TCC TCG TAG GCA – 3’
nDNA = 5’- TCG ATA CCT TAA GGA GCA TCC G -3’
Sensor: SWNT decorated with ss-DNA
cDNA
nDNA
300nm
Thicker sections denote DNA adsorbed on SWNT
Fluorescence energy : E = E11 + Eb
E11 = Energy of V1 – C1 transition
Eb= Exciton binding energy
Eb scales with effective environmental dielectric constant (ε)
Perebeinos, et. al. PRL, 92 (2004)
Binding energy relation:
Eb≈ Rn-2mn-1 ε-n
R = nanotube radius m = nanotube effective massn = scaling value of 1.4
Optical Transduction: Dielectric ModulationOptical Transduction: Dielectric ModulationOne dimensional structure confines exciton that forms on photo-absorption
-5
-4
-3
-2
-1
0
1
2
3
4
5
0 2 4 6 8 10
v1
c1
v2
Density of Electronic States
Ener
gy
c2
conduction
valence
E11fluorescence
E22absorption
( ) waterDNA ε1εε αα −+=Nanotube fluorescence linked to analyte adsorption via surface area (α)
Effective medium approximation
3.4 Å
4.6 Å
M2+cations
0.8
0.9
1
1.24 1.25 1.26Energy (eV)
0 mMHg2+84 mM
Hg2+
Nor
mal
ized
Int.
Divalent metal ions added to DNA-SWNT cause red shift in nanotube fluorescence
1.240
1.245
1.250
1.255
0.001 1 1000 1000000 1E+09Concentration (μM)
Ener
gy (e
V)
Mg2+
Ca2+
Co2+
Hg2+
Heller, D. A. et. al., Science 311 (2006)
Same relative sensitivity to divalent ions
Conformational polymorphism of nanotube-bound DNA
Detecting Changes in DNA Conformation
Detecting Changes in DNA Conformation
(6,5) SWNT PL50 mW, 785 nm
C0 a βB/ βZ NDNADNA-SWNT
70.8 µM 0.118 1.04 30102 µM 0.118 1.21 5
Hg2+ Concentration (μM)
Ener
gy (e
V)
[Θ]-5
(deg
-cm
2 /dm
ol)
DNA in solution
DNA on SWNT
1.240
1.244
1.248
1.252
0.0001 0.1 100 100000
-5.5
-3.5
-1.5
0.5
2.5
Hg2+ Concentration (μM)
Ener
gy (e
V)
[Θ]-5
(deg
-cm
2 /dm
ol)
DNA in solution
DNA on SWNTDNA on SWNT
1.240
1.244
1.248
1.252
0.0001 0.1 100 100000
-5.5
-3.5
-1.5
0.5
2.5
Compare CD and PL: common midpoints – Δ(ΔGibbs) ~ 0 thermodynamically similar transitions
Slopes at the inflections are different for SWNT-DNA and free DNA
Thermodynamic Comparison of DNA
Transitions on and off SWNT
Thermodynamic Comparison of DNA
Transitions on and off SWNT
1−
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛+⎟⎟
⎠
⎞⎜⎜⎝
⎛=
aN
oZ
B
aN
o CC
CCK
ββ
K = fraction of transitionC0 = DNA length-independent conc. a = binding sites/DNA length βB/ βZ = ratio of nucleation rates N = effective oligonucleotide length
Pohl F., Jovin, T, J. Mol. Biol. 67 (1972) Pohl, F., Cold Spring Harbor Quant. Biol. 47 (1982)
B-form Z-formB-formB-form Z-formZ-form
Shorter effective length
Probing the Effects of Nanotube DiameterProbing the Effects of Nanotube Diameter
21 −−→Δn
tn
ZB
rE
μ
Scaling from 1-D ExcitonSimulations1
Nanotube radiusEffective
mass
(6,5)
(7,5)(7,6)
(10,2)(9,4)
(9,5)
(8,4)
(11,1)
(8,6)(8,7)
Rel
ativ
e In
tens
ity
0
1
Emission Energy (eV)
Exci
tatio
n En
ergy
(eV)
2.3
(8,3)
3D plot of fluorescence maxima in excitation/emission space
3D plot of fluorescence maxima in excitation/emission space
0
1(6,5)
(7,5)(7,6)
(10,2)(9,4)
(9,5)
(8,4)
(11,1)
(8,6)(8,7)
Rel
ativ
e In
tens
ity
Emission Energy (eV)
Exci
tatio
n En
ergy
(eV)
Exci
tatio
n En
ergy
(eV)
2.3
(8,3)
0.009
0.013
0.017
0.021
0.025
0.029
0.35 0.40 0.45 0.50 0.55Nanotube Radius (nm)
(6,5)
(7,5)
(8,4)(7,6)
(10,2)(8,6)
(11,1)(9,5)
(8,7)
(8,3)
(9,4)21 −−→Δn
tn
ZB
rE
μ
52 mMHg2+
1. Perebeinos, et. al. PRL, 92 (2004)
Modeling Conformational Polymorphism on SWNT
⎟⎟⎠
⎞⎜⎜⎝
⎛−=Δ −−
→ nB
nZ
nt
nZB rAE
εεμ 1121
Exciton binding energy difference of B and Z forms modeled on change in dielectric constant (ε)
( ) DNAiOHii εαεαε +−= 21
Effective medium model accounts for changing ε using DNA surface area coverage on the nanotube
εDNA = 4.0 and εH2O = 88.1α = surface area
A, n, = empirical parametersµ = SWNT reduced effective massr = SWNT diameter
b
r
w
The surface area of the absorbed DNA helix is described by 3 parameters:
r = radius w = strand widthb = pitch
Heller, D. A. et. al., Science 311 (2006)
Equilibrium values of radius and pitch in B and Z DNA:
r0 b0
B form 1 nm 3.32 nmZ form 0.9 nm 4.56 nm
Transduction is Modeled using DNA Geometry
(Eb,b – Eb,z) for each nanotube:
0.009
0.013
0.017
0.021
0.025
0.029
0.35 0.40 0.45 0.50 0.55
21 −−→Δn
tn
ZB
rE
μ
Nanotube Radius (nm)
(6,5)
(7,5)
(8,4) (7,6)
(10,2)(8,6)
(11,1)(9,5)
(8,7)
(8,3)
(9,4)
0.009
0.013
0.017
0.021
0.025
0.029
0.35 0.40 0.45 0.50 0.55
21 −−→Δn
tn
ZB
rE
μ
Nanotube Radius (nm)
(6,5)
(7,5)
(8,4) (7,6)
(10,2)(8,6)
(11,1)(9,5)
(8,7)
(8,3)
(9,4)
Unchanging ε
ΔEb based on DNA geometry
Endocytosis of DNA-SWNT “sensors” within live cellsEndocytosis of DNA-SWNT “sensors” within live cells
1 μm
Fluorescence Mapping
Transmission Electron Micrograph
Nuclear envelope
EndosomeBound SWNT
Myoblast stem cells
Peri-nuclearSWNT
DA Heller, MS Strano, Advanced Materials 17 (2005) 2793-99
0.85
0.95
1.05
1.228 1.238 1.248
0 µM1000 µM
10000 µM
Energy (eV)
785 nm laser excitation and collection optics
Endosome-bound SWNT
3T3 fibroblast cell in media
20 µm
Hg2+ ionsperfused in
buffer
Applications for Metal Ion Detection Applications for Metal Ion Detection
1.237
1.242
1.247
1.252
0 10 1000 100000
Peak
Ene
rgy
(eV)
Hg2+ Concentration (µM)
Tissue
Black Ink
Whole Blood
Model from expt. in buffer.
Near infrared fluorescence through tissue
Whole blood
Heller, D. A. et. al., Science 311 (2006)
The Strano Group at University of Illinois
Post doctoral Researchers:
Seunghyun Baik (now Assist. Prof. at Sungkyunkwan
University, Korea)Jiang Zhang (not shown)Woo Jae Kim (not shown)
Jong Hyun Choi (not shown)
Graduate students: P. Barone D. HellerE. Jeng
M. UsreyC. Lee
R. GraffN. Nair (not shown)H. Jin (not shown)
R. Sharma (not shown)
E. Jeng D. HellerM. Usrey
P. Barone
S. BaikC. Lee
R. Graff