DNA-programmed assembly of a scalable, renewable, multiplexed redox protein-carbon nanotube biosensor

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DNA-programmed assembly of a scalable, renewable,
multiplexed redox protein-carbon nanotube
biosensor

• Gary D Withey, Jin Ho Kim, Jimmy Xu

DARPA/AFOSR MURI Project Direct nano-scale
conversion of biological signals into
electronic information
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The Highly-Ordered CNT Array

• MWNTs grown from AAO nanopore template
• CVD growth process

C. Papadopoulos et al. Intl J. Nanoscience, vol
1(3/4), 205-212, 2002.
CNT arrayelectrode
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Redox Protein Biosensing
Glucose oxidase model biosensor
Redox reaction cycles in the presence of glucose.
The higher the concentration of glucose, the
higher rate of turnover, the greater current peak
observed.
a. 0mM b. 5mM c. 10mM d. 20mM e. 50mM
f. 100mM
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CNT Properties

• High electrical conductivity
• Ease control of chemical functionalization

COOH
COOH
COOH
COOH
acid etching
further etching
COOH
HOOC
COOH
HOOC
HOOC
COOH
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Motivation for a self-assembling, addressable,
reversible molecular link

• Parallel, coordinated binding of a large
  diverse set of enzymes
• Easy replacement of old, inactive enzyme
• Swappability for modular sensor functionality

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Advantages of Using CNTs

• Preservation of active enzyme conformation
• Efficient electron transfer

Nanopatterning electrode surfaces for enhanced
electron transfer
equipotentiallines
bulk gold
CNT-modified
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The DNA Linking Scheme
SIAB
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DNA-Directed Self-Assembly of a Multiplexed
Biosensor
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Real-Time Detection of Five Substances
Each sensing region responds only to injections
of its respective substrate Hb NO GOx Glucose
ADH Ethanol LAX Lactic Acid GO Galactose
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Refreshability Swappability

• The link can be dehybridized in DIH20 at 65oC to
  refresh or swap linked enzymes

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Metalizing the DNA Link

• At high pH in the presence of Zn2, Ni2 and
  Co2, imino protons of guanine and thymine base
  pairs are replaced by the divalent metal cations
• This M-DNA exhibits metal-like conduction

Raikitin et al. Phys. Rev. Lett. 2000
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Effects of Metallization
Comparison of peak currents measured from GOx
linked by M-DNA, native DNA and a DNAMg2 control
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Acknowledgements

• Thanks to DARPA/AFOSR for their support through
  the MURI Program
• Thank you for your attention!