Schematics of fixture structure. Black in the cross-section views indicates location of fluid. Cross-section cutout view labels indicate system electrodes.
Schematics of the sensor and resistive heater portions of the fixture laminate.
Photographs of (a) ITO working electrode array and common pseudo-reference Au electrode, (b) Au working electrode array and common pseudo-reference Au electrode with PET mask defining the electroactive region (layer 2), and the PET layer defining the microfluidic channels (layer 3), (c) assembled fixture with platinum counter electrode and resistive heating element (layer 4) relative to a mm scale, and (d) fixture mounted in card edge connector with RTD.
Selective functionalization of Au electrodes in a microfluidic channel for multianalyte DNA detection occurred via the (a) electroaddressable deposition of nitrophenyl diazonium onto Au electrode 1, (b) electrodeposition of carboxylphenyl diazonium onto Au electrode 2, (c) covalent coupling of an amine terminated ssDNA probe against a sequence specific towards breast cancer to Au electrode 2 by carbodiimide chemistry, (d) electrodeposition of carboxylphenyl diazonium onto Au electrode 3, and (e) covalent coupling of an amine terminated ssDNA probe against a sequence specific towards colorectal cancer to Au electrode 3, again by carbodiimide chemistry.
Images of electrochemiluminescent reactions initiated by application of +2 V vs. Au pseudo-reference. (a) Black-box image of ECL reactions at each electrode with layer 2 and 3 design overlays. Images of individually addressed ECL reactions with white-light image overlays: (b) one electrode in each channel; (c) all electrodes in a signal channel. Images were captured from the underside of the laminate array, through the ITO electrodes.
(a) Microfluidic electrode array thermal profile and heater output during on-chip dsDNA melting. Set point = 85.0 °C, 5 min treatment. Actual temperature = 85.1 ± 0.43 °C. (b) Electrochemical current response obtained from 10 μM: ssDNA target sequence 2, dsDNA target sequence 2, and ssDNA control sequence 7 with on-chip melting (blue, red, and green, respectively), and dsDNA target sequence 2 without on-chip melting (white). Error bars are the standard deviation of measurements obtained from 3 electrodes.
Multianalyte detection of dsDNA sequences specific towards breast cancer (BC) and colorectal cancer (CC) on a single chip. Each channel contains three selectively modified electrodes: Electrode (1) DNA sequence 1 (BC probe), electrode (2) DNA sequence 4 (CC probe), and electrode (3) nitrophenyl surface (non-specific binding negative control). Arrays were treated with: channel (a) 10 μM dsDNA sequence 2 (BC target), channel (b) 10 μM dsDNA sequence 5 (CC target), and channel (c) 10 μM dsDNA sequence 2 with 10 μM dsDNA target sequence 5. Error bars are the standard deviation of measurements obtained from 3 independent microfluidic electrode arrays.
Reuse of microfluidic electrode array for dsDNA detection. Arrays were treated with 10 μM dsDNA sequence 2 in one channel (blue), and with 10 μM ssDNA control sequence 7 in another channel (red). Error bars are the standard deviation of measurements obtained from the 3 electrodes in the channel, except for * which is the average value and standard deviation across all 6 electrodes used in the given run after stripping. Stripping occurred via water flushing at 85 °C (heated via the integrated resistive heater) for 5 min. Between runs the arrays were stored with 2× SSC filled channels at 4 °C. Channels used for target or control DNA sequence treatments were alternated from run to run.
Breast cancer and colorectal cancer detection assay DNA sequences.
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