Carbon Nanotubes for Transistor Type-Biosensor and Therapeutic - - PowerPoint PPT Presentation

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5 th Korea-US NanoForum, Jeju, Korea, April 17-18, 2008 Carbon Nanotubes for Transistor Type-Biosensor and Therapeutic Applications Hee Cheul Choi Department of Chemistry, Pohang University of Science and Technology (POSTECH) South Korea,

SLIDE 1

Hee Cheul Choi

Department of Chemistry, Pohang University of Science and Technology (POSTECH) South Korea, 790-784

Carbon Nanotubes for Transistor Type-Biosensor and Therapeutic Applications

5th Korea-US NanoForum, Jeju, Korea, April 17-18, 2008

SLIDE 2

Surface Chemistry of Carbon nanotubes: Hybrid structures

Choi, et al., JACS 2002, 124, 9059. Lee and Choi, et al., Small 2005, 1, 975.

Noble metal-SWNT composites Transition metal-SWNT

Shin and Choi, et al., Adv. Mater. 2007, 19, 2873.

TiO2-SWNT composites

Facile and spontaneous synthetic approaches Mechanism

SLIDE 3

Intercalation of Li ions in pyrene-functionalized SWNT Modulation of band energy Schottky diode behavior Lithium intensity distribution (SPEM, Li 1s)

Lim and Choi, et al., JACS 2008, 130, 2160.

Surface Chemistry of Carbon nanotubes: Schottky diodes

SLIDE 4

O2 H2 CH4 C2H4 SiO CO

SiO2 Si

Byon and Choi, Nature Nanotech 2007, 2, 162. Byon and Choi, Nano Lett. 2008, 8, 178.

Carbothermal Reduction

Surface Chemistry of Carbon nanotubes: Carbothermal Reduction – Etching SiO2

SLIDE 5

Sub-10 nm scale Lithography using Nanotrenches

Byon and Choi, Nature Nanotech 2007, 2, 162.

SLIDE 6

Negative Differential Resistance (NDR) device

Ferritin captured in metallic SWNT nanogap electrodes
Electrically cut m-SWNT (gap = ca. 20 nm)
Electrostatically captured Ferritins
Peak current density: 4.0 x 106 A cm-2 (record)
Peak-to-Valley Ratio (PVR): ~ 40 (@ scan rate of 26 mV/s)
NDR is 1.2 µohm cm2

Apoferrtin Apoferrtin + Fe(III) Tang and Choi, et al., JACS 2007, 129, 11018.

Carbon nanotube electronics: Carbon nanotube/protein-based memory device

SLIDE 7

▪ Nonspecific Binding ▪ Specific Binding (using CDI-Tween20)

Robert J. Chen et al,. PNAS. 2003, 100, 4984

Electronic sensing of biomolecular recognitions using SWNTs-FETs

SLIDE 8

Sensitivity

At least ~ pM, grateful if it can go lower.
Protein detection limit of SWNT-FET: >10 nM

(c.f. Lieber group: ~ 10 fM detection limit of proteins using SiNW devices-Nat. Biotechol. 2005, 23, 1294.)

Feasibility

Prompt use: currently too long stabilization time
Nonspecific binding: perfect protection of devices with efficient

chemical blocking is mandatory. Hurdles to overcome

SLIDE 9

Nanotube aspect: Direct charge communication between proteins and nanotubes Metal-nanotube contact aspect: Schottky barrier modulation by protein adsorptions on metal surfaces

SiO2/Si

Au/Cr

Buffer Sol’n

Au/Cr

The two regions effecting to a biosensor sensitivity

SLIDE 10

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. Strongly depending on the pI (isoelectric point) values of proteins +

Metal

Energy

Semiconducting SWNT VB CB Fermi level matching (EFM = EFS) & Band bending of VB, CB EFS EFM buffer

The origin of conductance changes: Schottky Barrier

SLIDE 11

Pd/Au evaporation mPEG-SH SAM SiO2/Si PMMA SWNT s SiO2/Si SiO2/Si s s sssssssss s SiO2/Si ss s s Lift off SiO2/Si Lift off Device I

S O OMe n S O OMe n

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

.50x10

1.48 1.46 1.44 Ids (µΑ) 1200 800 400 Time (s) .50x10

3.45 3.40 3.35 3.30 Ids (µΑ) 1000 800 600 400 200 Time (s)

HIgG

Device I Device II 100 nM 100 nM

Experimental evidence for the detection mechanism

SLIDE 12

SiO2/Si

▪ Synthesis of network SWNTs ▪ Usage of the thin shadow mask ▪ Thermal evaporator with tilted angle stages

Au/Cr Au/Cr

Increased Schottky contact area for high performance

SLIDE 13

V

10 mV

2000 μm

200 µm

Teflon electrochemical cell

Protein Injection

1 μM

CVD (900℃ 10 min)

SiO2/Si Substrate with Catalyst CH4 H2 C2H4

Growth SWNTs ( R ~ 1 kΩ ) In wire

S D

(Cu)

S D

SiO2/Si

S D Choi and Dai et al. Nano Lett. 2003, 3, 157. Yang and Choi et al. Langmuir 2005, 21, 9198.

Fabrication of SWNT-FET having increased Schottky contact area

SLIDE 14

(a) SWNT FET device fabricated by a photolithography

SWNTs Photo Resist

(1) Metal Evaporation (2) Lift Off

SiO2/Si Au/Cr

(b) SWNT-FET device fabricated by a shadow mask at tilted angle

SWNTs Shadow Mask angle evaporation SiO2/Si Au/Cr Byon and Choi. J. Am. Chem. Soc. 2006, 128, 2188.

Fabrication of SWNT-FET having increased Schottky contact area

SLIDE 15

▪ SA ▪ SpA

A u / C r S i O2 / S i

1 pM sensitivity

a SWNT-FET fabricated by a shadow mask at tilted angle

Buffer sol’n Byon and Choi. J. Am. Chem. Soc. 2006, 128, 2188.

Highly sensitive SWNT-FET devices: Nonspecific bindings of proteins

SLIDE 16

1 pM sensitivity

a SWNT-FET fabricated by a shadow mask at tilted angle a SWNT-FET fabricated by a shadow mask <Protein : SpA>

(unit : pM) 10 nM sensitivity

Highly sensitive SWNT-FET devices: Nonspecific bindings of proteins

SLIDE 17

Treatment of 0.05% Tween20 after immobilizing probe proteins

▪ Probe protein: Protein A ▪ Target protein: rabbit IgG ▪ Probe protein: hCG ▪ Target protein: anti β-hCG

1 pM sensitivity

Highly sensitive SWNT-FET devices: Specific bindings of proteins

SLIDE 18

Acknowledgement

Collaborators

Prof. Joon Won Park (POSTECH)
Prof. Jillian M. Buriak (Univ. Alberta, Canada)
Prof. Insung S. Choi (KAIST)
Prof. Seunghun Hong (SNU)
Prof. Jin Yong Lee (SKKU)
Prof. Young Kyun Kwon (U. Mass)

Post Doctors

Dr. Hyeon Suk Shin
Dr. Hye Ryung Byon