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NER: Nanoscale Sensing and Control of Biological Processes Brown University, Providence, RI Jimmy Xu, Brown University ~ Charles R. Martin, University of Florida ~ Shana O. Kelley, University of Toronto ~ Joanne I. Yeh, University of Pittsburgh 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 Micro cyclic voltammetry measurement Analyte solution: 10 mM K3Fe(CN)6 in 1 M KNO3 Silicon microelectronic signal processing and control Flip and bond Approaches and Contributions: Design and calibration of a micro-cyclic voltammetry flow-chip prototype 2 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 network chip Flow-channel network Analyte I/O Digital I/O 0 100 mV/s -1 500 mV/s -2 0.6 Micro cyclic voltammetry flow-chip prototype fabrication Electrode array process 0.3 0.0 -0.3 Potential vs. Ag/AgCl (V) PECVD of Si3N4 Collaboration with P. Jaroenapibal, University of Pennsylvania Current density: 3.9 mA/cm2 compared to 0.21 mA/cm2 at a bulk gold electrode Current (nA) 0.4 Completed flow-cell chip Tip opening 0.0 Andres Jaramillo (undergraduate), Florida State University kf R Z O Y r0 0.4 0.2 Voltage Voltage 0.6 0 -0.2 T -0.4 Ultra-sensitive integrated enzymatic detector arrays -0.6 -0.8 -1 kb 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Time Time • Conical nanopore PET membrane fabricated by Martin group Large and positive charge number of O enhances migration current at nanoelectrode • 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 Detection of the changes in redox signals in the presence of H2O2 and NADH membrane contact pad • Membrane sections captured between orthogonal channels in the chip assembly process 0.5 0.0 PET membrane PDMS channel 4 2 Current density, FDC/r Current density, FDC/r 6 12 ZZ = −3 ZO = +3 +2 +1 0 −1 −2 −3 0 10 Electrode cell in glass: channel depth = 12 μm area of WE = 2.5 x 10-5 cm2 • Coupled channels: analyze → synthesize → analyze 14 107 • Planar working electrode also in each channel as a control ZZ = 0 Inlet 8 Current (nA) Large and negative charge number of Z suppresses the current plateau and enhances cathodic peak -0.5 -1.0 -1.5 Npx-PepCo-AuNP in KAc Npx-PepCo-AuNP in KAc + H2O2 -2.0 NPx-PepCo-AuNP in KAc + NADH Npx-AuNP in KAc Continuity of Au trace into channel 6 Glass channel 4 2 -2.5 0 0.8 -20 -15 -10 -5 0 5 Voltage, RT/F 10 15 20 -20 -15 -10 -5 0 5 10 15 20 0.6 0.4 0.2 0.0 Potential vs. Ag/AgCl (V) Voltage, RT/F Outlet -0.5 Molecular assembly of Npx system • Electrical connection to continuous deposited Au film on the PET membrane 12 -0.1 -0.2 -0.3 -0.4 Potential vs. Ag/AgCl (V) A self-assembled system consists of NADH peroxidase (Npx) enzyme, a metallized peptide, and a gold nanoparticle onto a microfluidic threeelectrode cell Base opening 0.8 Oe R 8 0.1 In collaboration with Prof. Joanne Yeh at University of Pittsburgh Medical Center Collaboration with Hitomi Mukaibo and Charles R. Martin, University of Florida 1 T= 0.2 0.0 In situ monitoring, sensing, control, and actuation of biomolecular reactions 10 0.3 -0.1 Gold Nanotubes as Flow-Through Bioreactors for Microfluidic Networks Electrocatalytic model design thiolated ssDNA hybridization with target DNA 0.5 Collaboration with Prof. Jimmy Xu at Brown Univ. Modeling and Simulation of Nanoelectrochemistry - peak current is proportional to (scan rate)1/2 2 µM thiolated ssDNA, 500 nM target DNA Assemble PDMS gasket to electrode substrate Nanocrystal array grown from Co catalyst in FIB-patterned Al2O3 -0.6 - formal potential is close to the literature values Analyte: 27 µM Ru(NH3)63+ and 2 mM Fe(CN)63- Cl2 plasma treatment to convert part of Ag to AgCl 1 μm anodic An increase in the electrocatalytic charge upon hybridization of the target DNA present at lowconcentration Working electrode surface area: 9 µm2 Etch Si3N4 using CF4 plasma Au dot 1.0 Collaboration with Prof. Shana O. Kelley, University of Toronto After Cl2 plasma of Ag and lift-off 30 µm 0.8 DNA hybridization detection Fabrication results E-beam evaporation of Ti/Au and liftoff PR Mask design 0.6 The functionality of the microfluidic three- electrode cell is confirmed: 200 mV/s Biosensor electronic chip 0.4 (Scan rate)1/2 (V/s)1/2 Integration: Chip package Si signal processors nanoelectrode array self-assembled linker system biomolecular target Nanowire array grown in FIB-patterned Al2O3; wire diameter less than 50 nm 0.2 1 V/s Flow-through nanopore membrance design for efficient in situ electrochemical synthesis and detection Nanoelectrode array fabrication onto working electrode cathodic 1 Current (nA) Electrochemical sensing module 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 Peak current (nA) Napat Triroj and Rod Beresford Collaborators: -0.2