Integration of electrochemical pH modulation with lab on a chip technologies

Abstract

At least one electrode is integrated on a lab on a chip cartridge in a sample preparation chamber of the cartridge, a DNA hybridization chamber of the cartridge, a protein assay chamber of the cartridge, and/or a detection chamber of the cartridge, for example, where the electrode is used to generate pH electrochemically in order to activate, deactivate, or intermediately attenuate an enzyme's activity on demand, in order to increase the fidelity of analyte detection, for cell lysis, for protein extraction, for DNA dehybridization, for primer hybridization control, for sample pre concentration, and/or for washing to remove non target species.

Claims

1. An apparatus comprising: a lab on a chip cartridge on which at least one electrode is integrated, wherein: the at least one electrode is integrated in at least one of a sample preparation chamber of the cartridge, a DNA hybridization chamber of the cartridge, a protein assay chamber of the cartridge, and a detection chamber of the cartridge; and one or more of the at least one electrode is configured to generate pH electrochemically and control pH of a solution within a distance of about 1 cm of the one or more of the at least one electrode.

2. The apparatus of claim 1, wherein one or more of the at least one electrode is used to generate pH electrochemically for one or more of cell lysis, protein extraction, DNA dehybridization, primer hybridization control, sample pre concentration, and washing to remove non target species.

3. The apparatus of claim 1, wherein one or more of the at least one electrode is used to generate pH electrochemically in order to activate, deactivate, or intermediately attenuate an enzyme's activity on demand.

4. The apparatus of claim 1, wherein one or more of the at least one electrode is used to generate pH electrochemically in order to increase the fidelity of analyte detection.

Description

SAMPLE PREPARATION APPLICATIONS

(1) In an example embodiment, electrochemical pH modulation is performed to change pH as a method to lyse cells, e.g., as a method to break down the cell wall of bacteria by alkaline lysis (see Birnboim et al., A rapid alkaline extraction procedure for screening recombinant plasmid DNA, Nucleic Acids Res. 7:1513-1518 (1979)) by generating a higher pH using an electrode, either using electroactive redox species or water hydrolysis, and this is performed on a LOC chip. This process can be used separately or in combination with thermal lysis. In the case of water hydrolysis, symmetric alternating current (AC) can be used to prevent evolution of H2 or O2 bubbles.

(2) In an example embodiment, there is integration of (a) an affinity substrate with (b) washing followed by (c) pH actuated elution by electrochemical pH modulation, all on a LOC chip. An example includes silica beads to adsorb DNA onto the surface, followed by changing the pH to promote DNA release for further downstream testing.

Hybridization Applications

(3) In an example embodiment, electrochemical pH modulation is performed on a LOC chip as a method to facilitate hybridization by disrupting the hydration shell around DNA as an alternative to using high salt concentrations or mercaptohexanol or other hybridization aids (see Whitten et al., Local conformational fluctuations can modulate the coupling between proton binding and global structural transitions in proteins, Proc. Natl. Acad. Sci. U.S.A 102, 4282-4287 (2005)).

(4) For DNA microarrays, electrochemical pH modulation on a LOC chip (such as one that includes a microarray) can be used to tune the hybridization to probe DNA strands, to reduce non-target hybridization.

(5) During polymerase chain reaction (PCR) cycling, electrochemical pH modulation on a LOC chip can be used to reduce hybridization of primers to non-target DNA strands.

Protein Assay Applications

(6) In an example embodiment, electrochemical pH modulation is used in a LOC cartridge (for example as described in U.S. patent application Ser. No. 14/254,968 and German Pat. App. No. DE102013200466.4).

Detection Applications

(7) The activity of most enzymes varies as a function of pH (Zhang et al., Optimization of DNA Hybridization Efficiency by pH-Driven Nanomechanical Bending, Langmuir, 28 (15), pp. 6494-6501 (2012)). In an example embodiment, for chemiluminescent assays, electrochemical pH modulation on a LOC chip is used to change pH in order to activate or deactivate an enzyme, enabling continuous signal readout, as opposed to end point detection (standard for chemiluminescent assays). Reducing the activity of an enzyme (i.e., partial deactivation) by the electrochemical pH modulation can also be used to extend dynamic range.