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Electrical Measurement of Single Molecule Catalysis using Carbon Nanotubes

Electrical Measurement of Single Molecule Catalysis using Carbon Nanotubes. Brett Goldsmith , Alexander Kane, Vaikunth Khalap , John Coroneus , Gregory Weiss, Phil Collins Department of Physics and Astronomy University of California Irvine. Outline. Single Molecule Sensor Construction

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Electrical Measurement of Single Molecule Catalysis using Carbon Nanotubes

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  1. Electrical Measurement of Single Molecule Catalysis using Carbon Nanotubes Brett Goldsmith, Alexander Kane, VaikunthKhalap, John Coroneus, Gregory Weiss, Phil Collins Department of Physics and Astronomy University of California Irvine

  2. Outline • Single Molecule Sensor Construction • Measurement of Catalysis Reaction Rate • Dynamics of the Bound State

  3. Single Molecule Sensors Ensemble Stochastic binding analyte absent binding analyte absent absent absent present present

  4. Device Construction Source PMMA PMMA Drain Coroneus, et al.Chem. Phys. Chem. accepted Goldsmith, et al.Science2007, 315, 77.

  5. Device Characterization

  6. The Catalysis Reaction EDC attached EDC urea + + EDC binds to the carboxyl group on the nanotube. The bound EDC perturbs the current in the nanotube. A reaction with water releases the bound EDC as a mixed urea.

  7. Functionalized CNTs in Buffer

  8. Interaction With EDC Goldsmith et al.Nano Lett.,8 (1), 189 -194, 2008

  9. Interaction With EDC Turnover Time Time Bonded Waiting Time

  10. Single Molecule Rate Constant Turnover Time Time Bonded Waiting Time k-1= 58.9 ± 18.3 s

  11. Bound State Lifetime Bound State Lifetime: <tbound> = 12.4 ± 2.1 s k-1= 58.9 ± 18.3 s

  12. Bound vs. Unbound

  13. Dynamics of the Bound State

  14. Energy of a Two Level System DE = kBTln(<tlo>/<thi>) ~11% of these states are very different

  15. Energy of a Two Level System 90% 10% at experimental pH = 4.5

  16. Reaction Intermediate States

  17. Summary Goldsmith, et al.Science2007, 315, 77. Goldsmith et al.Nano Lett.,8 (1), 189 -194, 2008 Goldsmith et al.JMR, accepted Coroneus, et al.Chem. Phys. Lett., accepted Dr. Phil Collins Brett Goldsmith Alex Kane Bucky Khalap Steve Hunt Danny Wan Tatyana Sheps Dr. Gregory Weiss John Coroneus ACS-PRF

  18. Other Samples… EDC Pthalic Anhydride JMR…

  19. Timescale of the Two Level System

  20. Amplitude of the Two Level System The amplitude of the two groups of bound states also differs. These different bound state properties could be due to the ~10% protonated EDC in solution at our conditions.

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