NER: Nanoscale Sensing and Control of Biological Processes

1
NER Nanoscale Sensing and Control of Biological
Processes
Collaborators Jimmy Xu, Brown University
Charles R. Martin, University of Florida Shana
O. Kelley, University of Toronto Joanne I. Yeh,
University of Pittsburgh
Napat Triroj and Rod Beresford Brown
University, Providence, RI
Micro cyclic voltammetry measurement
An on-chip biology-to-digital" sensing and
control system
Objective To provide a microelectronic and
microfluidic environment as a test bed for
nanoelectronic / biological interfaces to sense
and control low-level charge signals arising from
redox events at nanoelectrode complexes in
solution Approaches and Contributions Design
and calibration of a micro-cyclic voltammetry
flow-chip prototype Target DNA hybridization
detection at the micro-cyclic voltammetry
flow-chip Molecular assembly of a redox enzyme
system by a metallized peptide at the
three-microelectrode cell Development and
characterization of nanoelectrode array grown on
a Si substrate Flow-through nanopore membrance
design for efficient in situ electrochemical
synthesis and detection
Analyte solution 10 mM K3Fe(CN)6 in 1 M KNO3




Analyte I/O

• The functionality of the microfluidic three-
  electrode cell is confirmed
• formal potential is close to the literature
  values
• peak current is proportional to (scan rate)1/2

Digital I/O
Integration Chip package ? Si signal processors
? nanoelectrode array ? self-assembled linker
system ? biomolecular target
Nanoelectrode array fabrication onto working
electrode
Micro cyclic voltammetry flow-chip prototype
fabrication
DNA hybridization detection
Fabrication results
Electrode array process
Collaboration with Prof. Shana O. Kelley,
University of Toronto
Mask design
After Cl2 plasma of Ag and lift-off Working
electrode surface area 9 µm2
An increase in the electrocatalytic charge upon
hybridization of the target DNA present at
low-concentration Analyte 27 µM Ru(NH3)63 and 2
mM Fe(CN)63- 2 µM thiolated ssDNA, 500 nM
target DNA Current density 3.9 mA/cm2 compared
to 0.21 mA/cm2 at a bulk gold electrode
Au dot
1 µm
Completed flow-cell chip
Nanowire array grown in FIB-patterned Al2O3 wire
diameter less than 50 nm
Nanocrystal array grown from Co catalyst in
FIB-patterned Al2O3
Collaboration with P. Jaroenapibal, University of
Pennsylvania
Collaboration with Prof. Jimmy Xu at Brown Univ.
Modeling and Simulation of Nanoelectrochemistry
Gold Nanotubes as Flow-Through Bioreactors for
Microfluidic Networks
Molecular assembly of Npx system
In collaboration with Prof. Joanne Yeh at
University of Pittsburgh Medical Center
In situ monitoring, sensing, control, and
actuation of biomolecular reactions Collaboration
with Hitomi Mukaibo and Charles R. Martin,
University of Florida Andres Jaramillo
(undergraduate), Florida State University
Electrocatalytic model design
A self-assembled system consists of NADH
peroxidase (Npx) enzyme, a metallized peptide,
and a gold nanoparticle onto a microfluidic
three-electrode cell Detection of the changes in
redox signals in the presence of H2O2 and NADH

• In a conically shaped nanotube, flow from base
  to tip is continually focused to the tube wall,
  resulting in high conversion efficiency
• Resistance to flow can be adjusted at will by
  controlling the base opening, tip diameter, and
  cone angle

Voltage
T
Ultra-sensitive integrated enzymatic detector
arrays
membrane contact pad
Time

• Conical nanopore PET membrane fabricated by
  Martin group
• Membrane sections captured between orthogonal
  channels in the chip assembly process
• Electrical connection to continuous deposited Au
  film on the PET membrane

Large and positive charge number of O enhances
migration current at nanoelectrode Large and
negative charge number of Z suppresses the
current plateau and enhances cathodic peak

• Planar working electrode also in each channel as
  a control
• Coupled channels analyze ? synthesize ? analyze

Electrode cell in glass channel depth 12
µm area of WE 2.5 x 10-5 cm2
Continuity of Au trace into channel