brett goldsmith, alexander kane, vaikunth khalap, john coroneus, gregory weiss, phil collins...
TRANSCRIPT
Brett Go ldsmith , A l exander Kane , Va i kun th Kha lap , J ohn Coroneus , Gregory We i ss , Ph i l Co l l i n s
Depar tment o f Phys i cs and As t ronomyUn iver s i t y o f Ca l i f o rn i a I r v ine
Electrical Measurement of Single Molecule Catalysis using Carbon Nanotubes
Outline
Single Molecule Sensor Construction
Measurement of Catalysis Reaction Rate
Dynamics of the Bound State
Single Molecule Sensors Ensemble Stochastic
present absent
binding analyte absent present absent
binding analyte absent
Device Construction
ReferenceCounter
Source Drain
PMMAcoating
Electrolytedrop
PMMA
PMMA
Source
Drain
Coroneus, et al. Chem. Phys. Chem. accepted
Goldsmith, et al. Science 2007, 315, 77.
Device Characterization
The Catalysis Reaction
EDC binds to the carboxyl group on the nanotube.
EDC
+ +
attached EDC urea
The bound EDC perturbs the current in the nanotube.
A reaction with water releases the bound EDC as a mixed urea.
Functionalized CNTs in Buffer
Interaction With EDC
Goldsmith et al. Nano Lett., 8 (1), 189 -194, 2008
Interaction With EDC
Time Bonded Waiting Time
Turnover Time
Single Molecule Rate Constant
Time Bonded Waiting Time
Turnover Time
k-1= 58.9 ± 18.3 s
Bound State Lifetime
k-1= 58.9 ± 18.3 s
Bound State Lifetime:<tbound> = 12.4 ± 2.1 s
Bound vs. Unbound
Dynamics of the Bound State
Energy of a Two Level System
DE = kBT ln(<tlo>/<thi>)
~11% of these states arevery different
Energy of a Two Level System
90%
10%
at experimental pH = 4.5
Reaction Intermediate States
Summary
Dr. Phil CollinsBrett GoldsmithAlex KaneBucky KhalapSteve HuntDanny WanTatyana Sheps
Dr. Gregory WeissJohn Coroneus
ACS-PRF
Goldsmith, et al. Science 2007, 315, 77.
Goldsmith et al. Nano Lett., 8 (1), 189 -194, 2008
Goldsmith et al. JMR, accepted
Coroneus, et al. Chem. Phys. Lett., accepted
Other Samples…
EDC Pthalic Anhydride
JMR…
Timescale of the Two Level System
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.