BACKGROUND

Despite considerable efforts, current DNA sequencing methods face limitations in sequence read length, sensitivity, run time, and cost. To address these issues, various methods have been proposed that would allow individual DNA strands to be read directly. Among these, nanopore and nanochannel-based approaches have been proposed. However, many challenges exist related to fabricating a channel and/or pore opening that is sufficiently small to limit passage to a single DNA strand.

Other designs are needed.

SUMMARY

This disclosure is directed to DNA sequencing and devices therefor, particularly, to DNA sequencing and devices using free single nucleotides pairings with direct electrical detection of polymerase.

This disclosure provides, in one particular implementation, a DNA sequencing device having a first conductor electrically insulated from a second conductor, a voltage source and an amplifier, electrically connected in series with the first conductor and the second conductor, a DNA polymerase attached to the first conductor and to the second conductor with matching biotinylated tag molecules, and an electric current monitor.

In another particular implementation, this disclosure provides a method of DNA sequencing. The method includes providing a direct electrical detection of polymerase device, the device having a first conductor electrically insulated from a second conductor, a voltage source and an amplifier, electrically connected in series with the first conductor and the second conductor, and a DNA polymerase attached to the first conductor and to the second conductor, the conductors, voltage source, and amplifier forming a circuit. The method includes introducing a template DNA strand to the polymerase for transcription, applying a bias voltage to the circuit and measuring a current signal at an output of the amplifier, introducing free first nucleotides to the polymerase and monitoring the current signal for an increase, responsive to an increase in the current signal, detecting a match of a first nucleotide with a leading nucleotide of the template DNA strand or responsive to no increase in the current signal, determining no match of the first nucleotide with the leading nucleotide of the template DNA strand. After determining a match or no match, removing the free first nucleotides from the polymerase and introducing free second nucleotides different from the free first nucleotides to the polymerase and again monitoring the current signal for the increase.

This disclosure provides another particular implementation of a method of DNA sequencing using a device having a first conductor electrically insulated from a second conductor, a voltage source and an amplifier, electrically connected in series with the first conductor and the second conductor, and a DNA polymerase attached to the first conductor and to the second conductor via matched biotinylated tag molecules; the conductors, voltage source, and amplifier forming a circuit. The method includes introducing a template DNA strand to the polymerase, applying a bias voltage to the circuit and measuring a current signal at an output of the amplifier, the current signal having a baseline level, introducing a first type of free nucleotides to the polymerase and monitoring the current signal for an increase to a high level, the current signal increase provided by the polymerase during pairing and being non-discriminating on the type of free nucleotides being transcribed to the template DNA strand. Responsive to the current signal at the high level, determining a match of the first type of nucleotide with a leading nucleotide of the template DNA strand, or, responsive to the current signal at the baseline level, determining no match of the first type of nucleotide with the leading nucleotide of the template DNA strand.

The DNA sequencing device may be a microfluidic device, on a lab-on-a-chip platform with a physically or non-physically bounded fluid path, or may be on an electrode-gridded lab-on-a-chip. A microfluidic or lab-on-a-chip device provides a high level of parallelization.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. These and various other features and advantages will be apparent from a reading of the following detailed description.

