SYSTEMS, METHODS AND DEVICES FOR ELECTROCHEMICAL DETECTION USING HELPER OLIGONUCLEOTIDES
Disclosed herein are systems, devices, and methods for the electrochemical detection of a target using a helper oligonucleotide (each a helper oligo, or collectively, helper oligos).
1 . A method for detecting a target, the method comprising:
contacting a sample with a helper oligonucleotide capable of forming a first complex with a target in the sample;
contacting the sample with a probe affixed to a biosensor, wherein the probe is capable of forming a second complex with the first complex; and
measuring a first electrochemical signal at the biosensor, wherein the first electrochemical signal is indicative of the presence of the second complex.
2 . The method of claim 1 , further comprising determining that the target is present in the sample by comparing the first electrochemical signal to a second electrochemical signal measured absent the presence of the second complex.
3 . The method of claim 1 , wherein the first electrochemical signal is generated by charge accumulation at the surface of the biosensor in response to the formation of the second complex.
4 . The method of claim 1 , further comprising contacting the sample with an enzyme, wherein the helper oligonucleotide is capable of being enzymatically extended when the second complex is formed.
5 . The method of claim 4 , further comprising contacting the sample with a circular template, wherein a portion of the helper oligonucleotide is capable of binding to the circular template.
6 . The method of claim 5 , wherein the helper oligonucleotide is capable of being enzymatically extended by rolling circle amplification when the portion of the helper oligonucleotide is bound to the circular template.
7 . The method of claim 1 , wherein the helper oligonucleotide is tagged with a charged moiety.
8 . The method of claim 1 , wherein the helper oligonucleotide is partially hybridized to a branched oligonucleotide structure.
9 . The method of claim 1 , wherein the helper oligonucleotide is between 30 and 200 bases in length.
10 . The method of claim 1 , wherein a terminal end of the helper oligonucleotide is at least 3 bases away from a terminal end of the probe when the second complex is formed.
11 . The method of claim 1 , wherein the formation of the second complex is more thermodynamically favorable than a binding of the target to the probe in the absence of the helper oligonucleotide.
12 . The method of claim 1 , wherein, when the second complex is formed, a terminal end of the helper oligonucleotide is closer to a surface-bound terminal end of the probe than to a non-surface-bound terminal end of the probe.
13 . The method of claim 1 , wherein the helper oligonucleotide is between 30 and 100 bases in length.
14 . A point-of-care diagnostic device configured to perform the method of claim 1 .
15 . A biosensor comprising:
a solid support;
a probe affixed to the solid support;
a first chamber for contacting a sample with a helper oligonucleotide;
a second chamber for contacting the sample with the probe;
wherein:
the first chamber is operatively connected to the second chamber by a flow channel;
the probe is capable of forming a complex comprising the probe, the helper molecule, and a target suspected of being in the sample; and
control circuitry operably coupled to the solid support, wherein the control circuitry is configured to detect the presence of the complex.
16 . A point-of-care diagnostic device including the biosensor of claim 15 .